Global Geological And Climatic Events

Global Geological And Climatic Events

What are Medicanes?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Medicanes

Mains level : Frequent landfalls of tropical cyclones in India

Very recently, a medicane named Ianos made landfall along the coast of Greece and caused heavy rainfall and flooding on the islands of Zakynthos, Kefalonia and Ithaca.

Try this PYQ:

In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?

(a) Sea surface temperatures are low

(b) Inter-Tropical Convergence Zone seldom occurs

(c) Coriolis force is too weak

(d) Absence of land in those regions

What are Medicanes?

  • Medicanes are extra-tropical hurricanes observed over the Mediterranean Sea.
  • Medicanes occur more in colder waters than tropical cyclones, hurricanes and typhoons.
  • Hence, the cores of these storms are also cold, as compared to the warm cores of tropical cyclones.
  • Warmer cores tend to carry more moisture (hence rainfall), are bigger in size and have swifter winds.
  • The main societal hazard posed by Medicanes is not usually from destructive winds but through life-threatening torrential rains and flash floods.

Why in news?

  • This year is a mild La Niña, according to the World Meteorological Organization.
  • La Niña is the cooling phase of the El Niño Southern Oscillation (ENSO) cycle in the equatorial Pacific Ocean, as opposed to the warming El Niño phase.
  • It is characterized by the unusual cooling of the central and east-central equatorial Pacific Ocean.
  • A La Niña produces more rain in the central-eastern part, where most of the Mediterranean cyclones develop.

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Re-scaling the height of Mt Everest

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Himalayan orogeny

Mains level : NA

China and Nepal are expected to announce the latest official height of Mt. Everest.

Try this PYQ:

Q.When you travel to the Himalayas, you will see the following:

  1. Deep gorges
  2. U-turn river courses
  3. Parallel mountain ranges
  4. Steep gradients causing land-sliding

Which of the above can be said to be the evidences for the Himalayas being young fold mountains?

(a) 1 and 2 only

(b) 1, 2 and 4 only

(c) 3 and 4 only

(d) 1, 2, 3 and 4

Mt. Everest

  • Mount Everest or Sagarmatha, Earth’s highest mountain above sea level, is located in the Himalayas between China and Nepal -– the border between them running across its summit point.
  • Its current official elevation – 8,848m – places it more than 200m above the world’s second-highest mountain, K2, which is 8,611m tall and located in Pakistan-occupied Kashmir.
  • The mountain gets its English name from Sir George Everest, a colonial-era geographer who served as the Surveyor General of India in the mid-19th century.
  • Considered an elite climbing destination, Everest was first scaled in 1953 by the Indian-Nepalese Tenzing Norgay and New Zealander Edmund Hillary.

Everest’s first survey

  • The mission to measure the world’s highest peak was taken up on a serious note in 1847 and culminated with the finding of a team led by Andrew Waugh of the Royal Surveyor General of India.
  • The team discovered that ‘Peak 15’ — as Mt Everest was referred to then — was the highest mountain, contrary to the then-prevailing belief that Mt Kanchenjunga (8,582 m) was the highest peak in the world.
  • Another belief, prevailing even today, is that 8,840 m is not the height that was actually determined by the 19th-century team.
  • That survey, based on trigonometric calculations, is known as the Great Trigonometric Survey of India.

Why is the height being measured again?

  • Everest’s current official height– 8,848m– has been widely accepted since 1956, when the figure was measured by the Survey of India.
  • The height of the summit, however, is known to change because of tectonic activity, such as the 2015 Nepal earthquake.
  • Its measurement over the decades has also depended on who was surveying.
  • Another debate is whether the height should be based on the highest rock point or the highest snow point.

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What is the Hangenberg Crisis?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Hangenberg Crisis

Mains level : Mass Extinction

The explosion of a nearby star — occurred at between Devonian and Carboniferous periods — could have caused a mass extinction event that took place 359 million years ago.

Try this question from CSP 2018:

Q.The term “sixth mass extinction/sixth extinction” is often mentioned in the news in the context of the discussion of

(a) Widespread monoculture Practices agriculture and large-scale commercial farming with indiscriminate use of chemicals in many parts of the world that may result in the loss of good native ecosystems.

(b) Fears of a possible collision of a meteorite with the Earth in the near future in the manner it happened 65million years ago that caused the mass extinction of many species including those of dinosaurs.

(c) Large scale cultivation of genetically modified crops in many parts of the world and promoting their cultivationin other Parts of the world which may cause the disappearance of good native crop plants and the loss offood biodiversity.

(d) Mankind’s over-exploitation/misuse of natural resources, fragmentation/loss, natural habitats, destructionof ecosystems, pollution and global climate change.

Hangenberg crisis

  • The Earth suffered an intense loss of species diversity that lasted for at least 300,000 years.
  • The event is thought to have been caused by long-lasting ozone depletion, which would have allowed much more of the Sun’s ultraviolet (UV) radiation to reach and harm life on Earth.
  • It was called the Hangenberg crisis.

What did researchers find?

  • Extensive volcanism and global warming can also rupture the ozone layer but shreds of evidence for these are indefinite as far as the time period is concerned.
  • So, they up that one or more supernovae explosions, at a distance of 65 light-years away from the Earth, may have caused a prolonged loss of ozone.
  • Betelgeuse, a supernova, around 600 light-years away and present outside the kill distance of 25 light-years poses a danger today.
  • Events like gamma-ray bursts, solar eruptions and meteorite collisions end up very soon. As such, they cannot pave the way for gradual ozone depletion that took place at the close of the Devonian aeon.
  • A supernova event can be powerful enough to bathe its galaxy in light for days and months alike. It can be spotted across the universe as well.

Why Supernovae are considered dangerous?

  • Supernovae (SNe) are quick sources of ionizing photons that include fatal X-rays, UV and gamma rays.
  • Over a longer period of time, the bang clashes with the nearby gas, resulting in a shockwave that causes particle acceleration.
  • As such, cosmic rays are generated by SNe. These charged particles with high energies get magnetically confined on the inside of SN remains.
  • The fossil evidence shows a 300,000-year shrink in biodiversity leading the way to Devonian-Carboniferous Boundary (DCB) mass extinction.
  • This puts forward the possibility of multiple catastrophes or multiple supernovae explosions.

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Tornado’s dynamics and its India connection

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Tornado, Cyclones difference

Mains level : Rising events of Tropical Cyclone in India

Babu ChunderSikur Chatterjee’s paper was the earliest record of a tornado’s dynamics in the history of meteorology, according to a study.

Try this PYQ:

Q. In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason? (CSP 2015)

(a) Sea surface temperatures are low

(b) Inter-Tropical Convergence Zone seldom occurs

(c) Coriolis force is too weak

(d) Absence of land in those regions

What is a Tornado?

  • A tornado is a rapidly rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.
  • The windstorm is often referred to as a twister, whirlwind or cyclone winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern.
  • Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it.
  • It is generally accompanied by extreme weather such as heavy downpours, hail storms, and lightning.

Who was Babu ChunderSikur Chatterjee?

  • Chatterjee was an Indian scientist employed with the Surveyor General of India during the British colonial era.
  • He was likely the first person to scientifically document a tornado’s path in 1865, a study from the Indian Institute of Tropical Meteorology (IITM), Pune, has claimed.
  • Chatterjee had published his findings in a journal named Proceedings of the Asiatic Society of Bengal, in a paper titled ‘Note on a whirlwind at Pundooah’, near Hooghly.
  • The paper described a tornado’s dynamics in meticulous detail and was accompanied by a sketch that mathematically depicted its scale, track and rotation.

His work

 

  • Chatterjee quantitatively mapped the entire trail of á tornado’s destruction.
  • He benefited from the rare opportunity to observe a tornado passing through a railway track where there were conveniently placed markers at predefined locations.
  • This enabled him to observe and make clear measurements of the tornado’s direction, dynamics and path.

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Death Valley records the highest temperature on Earth

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Death Valley, Mojave Desert

Mains level : Not Much

California’s Death Valley registered a temperature of 54.4 degrees Celsius or 129.9 degrees Fahrenheit on August 16, 2020, which, once verified, could be the hottest temperature ever recorded on Earth.

Some years back, there was a question in the mains:

Major hot deserts in the northern hemisphere are located between 20-30 degree north and on the western side of the continents. Why?

Death Valley and its location

  • Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert.
  • It is one of the hottest places on Earth, along with deserts in the Middle East and the Sahara.
  • The valley is extremely dry because it lies in the rain shadow of four major mountain ranges (including the Sierra Nevada and the Panamint Range).
  • Moisture moving inland from the Pacific Ocean must pass eastward over the mountains to reach Death Valley; as air masses are forced upward by each range, they cool and moisture condenses, to fall as rain or snow on the western slopes.
  • When the air masses reach Death Valley, most of the moisture has already been lost and there is little left to fall as precipitation.

Key factors leading to its high temperature

  • Solar heating: The valley’s surface (consisting of soil, rocks, sand, etc.) undergoes intense solar heating because the air is clear and dry, and the land is dark and sparsely vegetated. This is especially noticeable in summer when the sun is nearly directly overhead.
  • Trapping of warm air: Warm air naturally rises and cools; in Death Valley, this air is subject to continual reheating as it is trapped by high, steep valley walls and recycled back to the valley floor.
  • Migration of warm air from other areas (advection): Warm desert regions adjacent to Death Valley, especially to the south and east, often heat air before it arrives in Death Valley.
  • Warm mountain winds: As winds are forced up and over mountains (e.g., the numerous ranges west of Death Valley), the winds can be warmed in several ways. The resulting dry, warm winds are known as foehn winds.

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In news: Mount Sinabung

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Mount Sinabung

Mains level : Not Much

The Mount Sinabung volcano in Indonesia has erupted spouting ash at least 5,000 metres high into the sky.

In the Philippines, a volcano called Taal on the island of Luzon; 50 km from Manila has recently erupted in January. Note all such recent eruption in news.

Also, try this PYQ:

Consider the following statements:

  1. The Barren Island volcano is an active volcano located in the Indian Territory.
  2. Barren Island lies about 140 km east of Great Nicobar
  3. The last time the Barren Island volcano erupted was in 1991 and it has remained inactive since then.

Which of the statements given above is/are correct? (CSP 2018)

(a) 1 only

(b) 2 and 3 only

(c) 3 only

(d) 1 and 3

Mount Sinabung

  • It is a Pleistocene-to-Holocene stratovolcano in the Karo plateau of Karo Regency, North Sumatra, Indonesia.
  • It is created by the subduction of the Indo-Australian Plate under the Eurasian Plate.
  • It erupted in 2010 after a 400-year-long hiatus and has been continuously active since September 2013.

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What is Seismic Noise?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Seismic noise

Mains level : Seismic activity and thier monitoring

The seismic noise level has dropped by as much as 50 per cent between March and May due to lockdowns this year, according to researchers.

Ever heard of space-based monitoring of seismic activities?  This topic creates a scope for potential prelims question…

What is Seismic Noise?

  • Seismic noise refers to vibrations within the Earth, which are triggered by natural and man-made phenomena like earthquakes, volcanoes and bombs.
  • Seismometers, specialised devices that record ground motions, also capture seismic noise.
  • Everyday human activity — such as road traffic, manufacturing in factories, the sound produced by planes roaring overhead, or simply people walking down the street.
  • The sound signals created by human beings are often referred to as anthropogenic seismic noise.
  • Seismic noise acts almost like background sound for seismologists — it is the unwanted component of signals recorded by a seismometer.

Variations in noise levels

  • The level of anthropogenic seismic noise recorded varies based on a number of factors.
  • Highly-populated urban areas will generate more vibrations from human activity than less densely populated regions.
  • Timing too plays an important role. The degree of seismic noise is found to be much lower during public holidays.

Why is this important to record this noise?

  • Due to this, scientists will be able to spot weaker signals.
  • Such small signals tell us about a geological fault making seismic hazard assessment more accurate.
  • This means that scientists will have a better shot at monitoring a whole range of seismogenic behaviour, including the smallest earthquakes or the early signs of a volcanic eruption.

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[pib] Ravines of Chambal-Gwalior Region

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Ravines, Chambal River

Mains level : Features of badland topography

Union Minister of Agriculture & Farmers’ Welfare held a meeting with World Bank representatives to bring large Ravines of Gwalior–Chambal region under agriculture.

Try this question for mains:

Q.What is Badland Topography? Discuss the scope of their utilization as arable land in India.

What are Ravines?

  • Badland topography is a major feature of the Chambal valley is characterized by an undulating floodplain, gullies and ravines.
  • Ravines are a type of fluvial erosional feature and are formed as a result of constant vertical erosion by streams and rivers flowing over semi-arid and arid regions.

How are they formed?

  • Researchers consider the regional climate as a major factor in the formation of ravines.
  • Climate indeed plays a huge role by supplying the water in the form of rain or snow as well as providing the temperature variations.
  • However, the ravines of Chambal are a bit difficult to be explained solely on climatic terms.
  • The region through which the Chambal River flows does not receive enough rainfall to create ravines that are 60–80 m deep.
  • Researchers have attributed neotectonic activities to the Chambal ravines genesis.

Other factors

  • It is well known that rivers are full of energy and actively erode in their initial phases and progressively become passive as they attain their base levels.
  • But sometimes, due to tectonic movements, the base level may be lowered further thus energizing the river and reactivating the erosion. This is known as River Rejuvenation.
  • Moreover, wind erosion has also contributed to the formation of Chambal ravines.

Back2Basics: What are Badlands?

  • Badlands are erosional landforms of highly dissected morphology that are created on soft bedrock in a variety of climate conditions.
  • They develop in arid to semiarid areas where the bedrock is poorly cemented and rainfall is generally heavy and intermittent.
  • The dry, granular surface material and light vegetation are swept from the slopes during showers, leaving the gullies bare.

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Lonar Lake turned pink due to ‘Haloarchaea’ microbes

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Lonar Crater Lake, Pleistoscene epoch

Mains level : Not Much

The colour of Lonar lake water in Maharashtra’s Buldhana district turned pink due to a large presence of the salt-loving ‘Haloarchaea’ microbes, a probe carried out by a Pune-based institute has concluded.

Make a note of all saltwater lakes in India. Few of them are Pulicat, Pangong Tso, Chilika, and Sambhar Lakes etc.

Haloarchaea’ microbes

  • Haloarchaea or halophilic archaea is a bacteria culture which produces pink pigment and is found in water saturated with salt.
  • The increased salinity and pH facilitated the growth of halophilic microbes, mainly Haloarchaea.
  • Basically, it is the biomass of these microbes and because of that, the surface of the water turned red or pink and as soon as the biomass subsided, the colour disappeared.
  • The scientist said the colour of the lake is now returning to original as the rainy season has kicked in, allowing dilution of the water.
  • Initially, it was thought for the red-pigmented Dunaliella algae due to which the water might have turned pink.
  • Because of that, the salinity and pH/alkalinity levels have also come down and green algae have started growing in the water body.

About Lonar Lake

  • Lonar Lake, also known as Lonar crater, is a notified National Geo-heritage Monument, saline (pH of 10.5), Soda Lake, located at Lonar in Buldhana district, Maharashtra.
  • It was created by an asteroid collision with earth impact during the Pleistocene Epoch.
  • It is one of the four known, hyper-velocity, impact craters in basaltic rock anywhere on Earth.
  • It sits inside the Deccan Plateau—a massive plain of volcanic basalt rock created by eruptions some 65 million years ago.
  • Its location in this basalt field suggested to some geologists that it was a volcanic crater.

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‘Churachandpur Mao Fault’ in Mizoram

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Churachandpur Mao Fault

Mains level : Plate tectonics and continental drift theories

Mizoram’s zone of “scary” earthquakes is caught between two subterranean faults called the ‘Churachandpur Mao Fault’.

Try this question from CSE Mains 2014:

Q.Why are the world’s fold mountain systems located along the margins of continents? Bring out the association between the global distribution of Fold Mountains and the earthquakes and volcanoes.

Churachandpur-Mao Fault (CMF)

  • The CMF is named after two places in Manipur and runs north-south into Myanmar along the border of Champhai.
  • The Mat Fault runs northwest-southeast across Mizoram, beneath river Mat near Serchhip.
  • It is defined by straight valleys; most prominent being between Kangpokpi and Maram region of Mizoram.
  • The fault takes a north-easterly trend from Maram where the fault zone is characterized by active landslides during the monsoon.

Why study CMF?

  • Faults are discontinuities or cracks that are the result of differential motion within the earth’s crust.
  • Vertical or lateral slippage of the crust along the faults causes an earthquake.

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Rapid Intensification of Cyclones

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Marsupial theory, MJO , MISO, El-Nino, La-Nina

Mains level : Tropical Cyclones

Tropical cyclones remain the deadliest natural climate hazard that causes an unacceptably high loss of life, property and infrastructure.  Global warming has already resulted in a detectable increase in the number of higher intensity cyclones as well as their intensification.

Also read:

[Burning Issue] Tropical Cyclones and India

Try this question:

Q. The Marsupial Theory often seen in news is related to which of the climatic phenomena?

a) Heatwaves b) Monsoon Variability c) Formation of Cyclones d) Thunderstorms

What is Rapid Intensification of Cyclones?

  • RI is defined as an increase in maximum sustained winds by at least 55 km/hour in a 24-hour period.
  • Such acceleration can only come with a rapid drop in the pressure in the eye of the cyclone.
  • Rapid intensification (RI) is making cyclone forecasts harder and intense cyclones with RI are expected to grow in number.
  • The lack of understanding of the transition from a seedling of a cyclone, like a low-pressure system to a tropical storm, limits extending the forecast lead times.

Factors causing RI

The most important environmental factors for cyclone genesis are-

  • the rotation or vorticity of a low-pressure system at the surface;
  • sea surface temperatures or the volume of warm water available;
  • the vertical motion of air in this low-pressure system;
  • the amount of humidity available in the middle atmosphere and
  • the vertical shear or the change in winds from the surface to the upper atmosphere.

MJO and Cyclones

  • Madden-Julian Oscillations as they are known, dominate the tropics during October-April by propagating from the western Indian Ocean into the eastern Indian Ocean, across the Indonesian seas into the Pacific Ocean.
  • Referred to as MJOs, these Madden-Julian Oscillations throw seeds of rotational low-pressure systems over the Indian and the Pacific Oceans.
  • And thus, MJOs show a strong association with cyclogenesis, especially for the post-monsoon season.

Impacts of MISO

  • Monsoon Intraseasonal Oscillations (MISO) are alternating periods of heavy and minimal rainfall, each lasting for about a month or so and tending to follow a cyclical, northward shifting pattern from the equator to southern Asia.
  • While the strong vertical shear suppresses cyclones during the monsoon season, MISOs influence cyclone genesis during the pre-monsoon season.

Other factors

  • At longer timescales, phenomena like the El Niño and La Niña influence not only the number of cyclone seeds but also the location and the expanse of warm water.
  • For example, during the pre-monsoon season of La Niña year, the region of warm water over the Bay of Bengal increases. This leads cyclones to travel longer and grow stronger than during an El Niño year.
  • Over the Pacific Ocean, on the other hand, it is the El Niño that provides a larger swath of warm water and more intense cyclones.
  • West Africa produces waves called easterly waves that propagate west from land onto the tropical Atlantic Ocean and sow the seeds for most hurricanes.
  • Extensive analysis has produced theories that are evocatively called the Marsupial Theory — a wave pouch that allows cyclones to grow, or waves interacting to produce a Kelvin cat’s eye, which is a ‘sweet-spot’ for the birth of a cyclone.

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The lost continent of Zealandia

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Zealandia

Mains level : Zealandia and its features

A new map has revealed the lost continent of Zealandia.

The ocean relief can be divided into various parts such as Continental Shelf, Continental Slope, Continental Rise or Foot, Deep Ocean basins, Abyssal plains & Abyssal Hills, Oceanic Trenches, Seamounts and Guyots.

Revise these ocean bottom relief features from your basic references.

Also revise India’s Deep Ocean Mission.

About Zealandia

  • Zealandia — or Te Riu-a-Māui, as it’s referred to in the indigenous Māori language — is a 2 million-square-mile (5 million square kilometres) continent east of Australia, beneath modern-day New Zealand.
  • Scientists discovered the sprawling underwater mass in the 1990s, then gave it formal continent status in 2017.
  • Still, the “lost continent” remains largely unknown and poorly studied due to its Atlantean geography.

Its formation

  • It is a group of submerged pieces of crust that separated from the ancient supercontinent Gondwana about 85 million years ago.
  • Gondwana was formed when Earth’s ancient supercontinent, Pangea, split into two fragments.
  • Laurasia was transformed into North America, Asia, and Europe, while Gondwana became Africa, South America, Australia, and Antarctica.
  • But land masses continued to be rearranged afterwards, with Zealandia breaking off Gondwana.

Data revealed by the new map

  • The new maps reveal Zealandia’s bathymetry (the shape of the ocean floor) as well as its tectonic history, showing how volcanism and tectonic motion have shaped the continent over millions of years.
  • Data for the bathymetric map was provided by the Seabed2030 project — a global effort to map the entire ocean floor by 2030.

Why call it a continent?

  • Zealandia was classified as a “microcontinent,” as the island of Madagascar, until 2017.
  • But according to Mortimer, it has all the requirements to be classified as a continent.
  • It has defined boundaries; it occupies an area of over one million square kilometres and is elected above the ocean crust.

Also read: https://www.civilsdaily.com/news/seabed-2030-project/

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What is ‘Last Glacial Maximum’?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Last Glacial Maximum

Mains level : Nature induced Climate Change

Researchers analysed simulations of this past climate and predicted that the ongoing climate change could reawaken an ancient climate pattern of the Indian Ocean Region (IOR).

Try this question from CSP 2017:

Q.With reference to ‘Indian Ocean Dipole (IOD)’, sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?

1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.

2. An IOD phenomenon can influence El Nino’s impact on the monsoon.

Select the correct Option using the code given below:

(a) Only 1

(b) Only 2

(c) Both 1 and 2

(d) Neither 1 nor 2

The Last Glacial Maximum

  • The Last Glacial Maximum (LGM) was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent.
  • Vast ice sheets covered much of North America, Northern Europe, and Asia and profoundly affected Earth’s climate by causing drought, desertification, and a large drop in sea levels.
  • Growth of ice sheets commenced 33,000 years ago and maximum coverage was between 26,500 years and 19–20,000 years ago, when deglaciation commenced in the Northern Hemisphere.
  • It caused an abrupt rise in sea level.

Shells predict IOR climate variability

  • By studying microscopic zooplankton called foraminifera, the team had published a paper in 2019 which first found evidence from the past of an Indian Ocean El Niño.
  • Foraminifera builds a calcium carbonate shell, and studying these can tell us about the properties of the water in which they lived.
  • The team measured multiple individual shells of foraminifera from ocean sediment cores and was able to reconstruct the sea surface temperature conditions of the past.
  • The Indian Ocean has the capacity to harbour much larger climate variability than observed during the last few decades or a century.

Lessons to learn

  • There are many lessons to be learnt from this cooler period about our warmer future.
  • As it is, under present-day conditions, changes in the Indian Ocean Dipole and the El Niño–Southern Oscillation strongly affect Indian Monsoon variability from year to year.
  • If the hypothesized ‘equatorial mode’ emerges in the near future, it will pose another source of uncertainty in rainfall prediction and will likely amplify swings in monsoon rainfall.
  • It could bring more frequent droughts to East Africa and southern India and increased rainfall over Indonesia.

Back2Basics

What is the Indian Ocean Dipole? Explain its connection with the Indian monsoons

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What is the Anthropause Period?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Anthropause, Anthropocene

Mains level : Human impact on gelological time scale

Researchers in the UK are set to study the “Anthropause”, a term they have coined to refer to the coronavirus-induced lockdown period and its impact on other species.

Practice question for mains:

Q. What is the significance of declaring Anthropocene epoch? Discuss how it is different from any geological events. Discuss the Anthropause Period.

Anthropause Period

  • Researchers have suggested the lockdown period, which is also being referred to as the “Great Pause”, be referred to with a more precise term.
  • It is referred specifically to a considerable global slowing of modern human activities, notably travel.
  • The unprecedented curbs imposed on millions of people around the world, mainly due to restrictions in travel, led to reports of unusual animal behaviour.
  • For instance, there were pumas sighted in Chile’s Santiago, jackals in the parks of Tel Aviv in Israel, dolphins in the waters of Italy and even a monkey fight on the streets of Thailand.
  • The researchers believe studying this period will provide valuable insights into the relationship between human-wildlife interactions in the 21st century.

What do the researchers hope to find?

  • As a result of the lockdown, nature appears to have changed, especially in urban environments, since not only are there now more animals, but also some “unexpected visitors.”
  • In their outline, researchers mention how the scientific community can use these “extraordinary circumstance” provided by global lockdowns to understand how human activity affects wildlife.
  • On the other hand, there are some animals for which the lockdown may have made things more challenging.
  • For instance, for various urban-dwelling animals, such as rats, gulls and monkeys who depend on food provided or discarded by humans, the lockdown would have made life more difficult.

Why is studying the lockdown important?

  • Expanding human populations continue to transform their environments at unprecedented rates.
  • Further, because the reduction in human activity during the lockdown on both land and sea has been “unparalleled” in recent history, the effects have been “drastic, sudden and widespread”.
  • Essentially, this gives them a chance to study the extent to which modern human mobility affects wildlife.
  • The study can be linked can help provide insights that may be useful in preserving global biodiversity, maintaining the integrity of ecosystems and predicting global zoonoses and environmental changes.

Back2Basics

Anthropocene as Earth’s new epoch

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‘Ring of Fire’ Solar Eclipse

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Solar Eclipse and related terms, Summer Solstice

Mains level : Not Much

A rare celestial event, an annular solar eclipse popularly called as the ‘ring of fire’ eclipse, will be visible on June 21, 2020 from some parts of Northern India. The first solar eclipse of this year takes place on the summer solstice, which is the longest day in the Northern Hemisphere.

Try this question from CSP 2019:

Q. On 21st June, the Sun

(a) Does not set below the horizon at the Arctic Circle

(b) Does not set below the horizon at Antarctic Circle

(c) Shines vertically overhead at noon on the Equator

(d) Shines vertically overhead at the Tropic of Capricorn

What is the Solar Eclipse?

  • A Solar Eclipse happens when the moon while orbiting the Earth comes in between the sun and the Earth, due to which the moon blocks the sun’s light from reaching the Earth, causing an eclipse of the sun or a solar eclipse.
  • According to NASA, people who are able to view the total solar eclipse are in the centre of the moon’s shadow as and when it hits the Earth.
  • There are three types of eclipses: one is a total solar eclipse, which is visible only from a small area on Earth. A total solar eclipse happens when the sun, moon and Earth are in a direct line.
  • The second type of a solar eclipse is a partial solar, in which the shadow of the moon appears on a small part of the sun.

Annular Solar Eclipse

  • The third kind is an annular solar eclipse, which happens when the moon is farthest from the Earth, which is why it seems smaller.
  • In this type of an eclipse, the moon does not block the sun completely, but looks like a “dark disk on top of a larger sun-coloured disk” forming a “ring of fire”.
  • Furthermore, during a solar eclipse, the moon casts two shadows on the Earth; the first one is called the umbra, which gets smaller as it reaches the Earth.
  • The second one is called the penumbra, which gets larger as it reaches the Earth.
  • According to NASA, people standing in the umbra see a total eclipse and those standing in the penumbra see a partial eclipse.

Why the study of solar eclipse is crucial?

  • One of the reasons that NASA studies solar eclipses is to study the top layer of the sun called the corona.
  • During an annular eclipse, NASA uses ground and space instruments to view this top layer when the sun’s glare is blocked by the moon.

Back2Basics: Summer Solstice

  • The summer solstice occurs when one of the Earth’s poles has its maximum tilt toward the Sun.
  • It happens twice yearly, once in each hemisphere (Northern and Southern).
  • For that hemisphere, the summer solstice is when the Sun reaches its highest position in the sky and is the day with the longest period of daylight.
  • Within the Arctic circle (for the northern hemisphere) or Antarctic circle (for the southern hemisphere), there is continuous daylight around the summer solstice.
  • On the summer solstice, Earth’s maximum axial tilt toward the Sun is 23.44°. Likewise, the Sun’s declination from the celestial equator is 23.44°.

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Lonar Lake colour changes to pink

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Lonar Crater Lake, Pleistoscene epoch

Mains level : NA

The colour of water in Maharashtra’s Lonar Lake, formed after a meteorite hit the Earth some 50,000 years ago, has changed to glaring.

Make a note of all saltwater lakes in India. Few of them are Pulicat, Pangong Tso, Chilika, and Sambhar Lakes etc.

About Lonar Lake

  • Lonar Lake, also known as Lonar crater, is a notified National Geo-heritage Monument, saline (pH of 10.5), Soda Lake, located at Lonar in Buldhana district, Maharashtra.
  • It was created by an asteroid collision with earth impact during the Pleistocene Epoch.
  • It is one of the four known, hyper-velocity, impact craters in basaltic rock anywhere on Earth.
  • It sits inside the Deccan Plateau—a massive plain of volcanic basalt rock created by eruptions some 65 million years ago.
  • Its location in this basalt field suggested to some geologists that it was a volcanic crater.

Why there’s a color change?

  • The salinity and algae can be responsible for this change.
  • There is no oxygen below one meter of the lake’s water surface.
  • There is an example of a lake in Iran, where water becomes reddish due to increase in salinity.
  • The level of water in the Lonar Lake is currently low as compared to the few past years and there is no rain to pour fresh water in it.
  • The low level of water may lead to increased salinity and change in the behaviour of algae because of atmospheric changes.

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Permafrost and the hazards of its Thawing

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Permafrost

Mains level : Paper 1-Permafrost thaw.

The principal reason that led to the recent 20,000-tonne oil leak at an Arctic region power plant in Russia that is now being recognised is the sinking of ground surface due to permafrost thaw.

Try this question from Mains 2017:
Q. What is Cryosphere? How does the Cryosphere affect global climate?

What is Permafrost?

  • Permafrost is ground that remains completely frozen at 0 degrees Celsius or below for at least two years.
  • It is defined solely based on temperature and duration.
  • The permanently frozen ground, consisting of soil, sand, and rock held together by ice, is believed to have formed during glacial periods dating several millennia.

Where are they found?

  • These grounds are known to be below 22 per cent of the land surface on Earth, mostly in polar zones and regions with high mountains.
  • They are spread across 55 per cent of the landmass in Russia and Canada, 85 per cent in the US state of Alaska, and possibly the entirety of Antarctica.
  • In northern Siberia, it forms a layer that is 1,500 m thick; 740 m in northern Alaska.
  • At lower latitudes, permafrost is found at high altitude locations such as the Alps and the Tibetian plateau.

How climate change is eating away at these grounds?

  • The Earth’s polar and high altitude regions — its principal permafrost reservoirs — are the most threatened by climate change.
  • Arctic regions are warming twice as fast compared to the rest of the planet, its current rate of temperature change being the highest in 2,000 years.
  • In 2016, Arctic permafrost temperatures were 3.5 degrees Celsius higher than at the beginning of the 20th century.
  • A study has shown that every 1 degree Celsius rise in temperature can degrade up to 39 lakh square kilometre due to thawing.
  • This degradation is expected to further aggravate as the climate gets warmer, putting at risk 40 per cent of the world’s permafrost towards the end of the century– causing disastrous effects.

The threat to infrastructure

  • Thawing permafrost is also ominous for man-made structures overhead.
  • The Russian oil leak occurred recorded temperatures in Siberia at more than 10 degrees Celsius above average, and called them “highly anomalous” for the region where the power plant is located.
  • As temperatures rise, the binding ice in permafrost melts, making the ground unstable and leading to massive potholes, landslides, and floods.
  • The sinking effect causes damage to key infrastructure such as roads, railway lines, buildings, power lines and pipelines.
  • These changes also threaten the survival of indigenous people, as well as Arctic animals.

A ticking time bomb

  • Beneath its surface, permafrost contains large quantities of organic leftover from thousands of years prior — dead remains of plants, animals, and microorganisms that got frozen before they could rot.
  • It also holds a massive trove of pathogens.
  • When permafrost thaws, microbes start decomposing this carbon matter, releasing greenhouse gases like methane and carbon dioxide.
  • Researchers have estimated that for every 1 degree Celsius rise in temperature, these grounds could release GHGs to the tune of 4-6 years’ of emissions from coal, oil, and natural gas.
  • Along with greenhouse houses, these grounds could also release ancient bacteria and viruses into the atmosphere as they unfreeze.

Back2Basics
https://www.civilsdaily.com/news/thawing-of-permafrost/

Also read:

Ambarnaya River Oil spill in Russia

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What is Lunar Eclipse?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Lunar and Solar Eclipse

Mains level : Not Much

A penumbral lunar eclipse will be observed today midnight. The Earth will imperfectly align itself between the Sun and the moon, casting a shadow on the latter, marking the second lunar eclipse of the year.

Solar and Lunar eclipse has been quite frequent this year. Mark the major differences between them.

Lunar Eclipse

  • A lunar eclipse occurs when the Moon moves into the Earth’s shadow.
  • This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned with Earth between the other two.
  • A lunar eclipse can occur only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon’s proximity to either node of its orbit.
  • Any object that obstructs light will produce two shadows: one which will be dark and dense, is called the umbra; and the other which is light and diffused is called the penumbra.
  • The only light reflected from the lunar surface has been refracted by Earth’s atmosphere.
  • This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light. Due to this reddish colour, a totally eclipsed Moon is sometimes called a blood moon.

Types

  • In a total eclipse of the moon, the inner part of Earth’s shadow, called the umbra, falls on the moon’s face. At mid-eclipse, the entire moon is in shadow, which may appear blood red.
  • In a partial lunar eclipse, the umbra takes a bite out of only a fraction of the moon. The dark bite grows larger and then recedes, never reaching the total phase.
  • In a penumbral lunar eclipse, only the more diffuse outer shadow of Earth – the penumbra – falls on the moon’s face. This third kind of lunar eclipse is much more subtle and much more difficult to observe than either a total or partial eclipse of the moon.

How it is different from Solar Eclipse?

  • A solar eclipse happens when the moon passes in between the earth and the sun. A lunar eclipse happens when the earth passes in between the moon and the sun.
  • During a solar eclipse, the moon partially or fully hides the sun’s rays for a few minutes.
  • Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth.
  • Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.

What’s special this time?

  • This eclipse is also called a strawberry moon eclipse — the term, interestingly, originates from an American concept and has little to do with the Euro-Asia region.
  • June’s full moon usually coincides with the harvesting season of wild strawberries in America and the phenomenon was often addressed in reference to that.
  • India had already witnessed an eclipse earlier this year, in January.
  • The strawberry moon eclipse is going to be its second and probably the last visible lunar one in 2020.

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The Sixth Mass Extinction

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Sixth Mass Extinction

Mains level : Mass Extinction

Click here for high resolution of the image: National Geographic

The ongoing sixth mass extinction may be one of the most serious environmental threats to the persistence of civilization, according to new research published in an American journal.

Try this question from CSP 2018:

The term “sixth mass extinction/sixth extinction” is often mentioned in the news in the context of the discussion of

(a) Widespread monoculture Practices agriculture and large-scale commercial farming with indiscriminate use of chemicals in many parts of the world that may result in the loss of good native ecosystems.

(b) Fears of a possible collision of a meteorite with the Earth in the near future in the manner it happened 65million years ago that caused the mass extinction of many species including those of dinosaurs.

(c) Large scale cultivation of genetically modified crops in many parts of the world and promoting their cultivationin other Parts of the world which may cause the disappearance of good native crop plants and the loss offood biodiversity.

(d) Mankind’s over-exploitation/misuse of natural resources, fragmentation/loss, natural habitats, destructionof ecosystems, pollution and global climate change.

Highlights of the research

  • The study analysed 29,400 species of terrestrial vertebrates and determined which of these are on the brink of extinction because they have fewer than 1,000 individuals.
  • The disappearance of their component populations has been occurring since the 1800s.
  • Most of these 515 species are from South America (30 per cent), followed by Oceania (21 per cent), Asia (21 per cent) and Africa (16 per cent) among others.

The Anthropocene Extinction

  • Mass extinction refers to a substantial increase in the degree of extinction or when the Earth loses more than three-quarters of its species in a geologically short period of time.
  • So far, during the entire history of the Earth, there have been five mass extinctions.
  • The sixth, which is ongoing, is referred to as the Anthropocene extinction.
  • The five mass extinctions that took place in the last 450 million years have led to the destruction of 70-95 per cent of the species of plants, animals and microorganisms that existed earlier.
  • These extinctions were caused by “catastrophic alterations” to the environment, such as massive volcanic eruptions, depletion of oceanic oxygen or collision with an asteroid.
  • After each of these extinctions, it took millions of years to regain species comparable to those that existed before the event.

So what is the sixth mass extinction then?

  • Researchers have described it as the “most serious environmental problem” since the loss of species will be permanent.
  • Even though only an estimated 2% of all of the species that ever lived are alive today, the absolute number of species is greater now than ever before.
  • The research claims that this extinction is human-caused and is more immediate than climate destruction.

Major drivers of mass extinction

  • Significantly, the study calls for a complete ban on wildlife trade as many of the species currently endangered or on the brink of extinction are being decimated by legal and illegal wildlife trade.
  • The current COVID-19 pandemic, while not fully understood, is also linked to the wildlife trade.
  • There is no doubt that there will be more pandemics if man continues destroying habitats and trading wildlife for own consumption as food and traditional medicines.

What happens when species go extinct?

  • When species go extinct, the impact can be tangible such as in the form of a loss in crop pollination and water purification.
  • Further, if a species has a specific function in an ecosystem, the loss can lead to consequences for other species by impacting the food chain.
  • The effects of extinction will worsen in the coming decades as the resulting genetic and cultural variability will change entire ecosystems.
  • If the number of individuals in a population or species drops, their contributions to ecosystem services become unimportant.
  • Their genetic variability and resilience is reduced, and its contribution to human welfare may be lost.” the study says.

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What is South Atlantic Anomaly?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Van Allen Radiation Belt, South Atlantic Anomaly

Mains level : South Atlantic Anomaly and its impact

New data obtained by the European Space Agency (ESA) Swarm satellites has revealed the existence of a mysterious anomaly weakening the Earth’s magnetic field. Termed as ‘South Atlantic Anomaly’, it extends all the way from South America to southwest Africa.

The term ‘South Atlantic Anomaly’ at its first sight looks similar to any climate/oceanic current related phenomena. But it’s not! This is where you can end up losing 2.66 marks in the prelims!

What is South Atlantic Anomaly (SAA)?

  • The SAA is referred to the behaviour of Earth’s Geo-Magnetic field in an area between Africa and South America.
  • The SAA is an area where the Earth’s inner Van Allen radiation belt comes closest to the Earth’s surface, dipping down to an altitude of 200 kilometres.
  • This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher-than-usual levels of radiation.
  • The effect is caused by the non-concentricity of the Earth and its magnetic dipole.
  • The SAA is the near-Earth region where the Earth’s magnetic field is weakest relative to an idealized Earth-centered dipole field.

Weakening of the magnetic field

  • Over the last 200 years, the magnetic field has lost around 9% of its strength on a global average.
  • A large and rapid shrink has been observed in the SAA region over the past 50 years just as the area itself has grown and moved westward.
  • The weakening of the magnetic field is also causing technical difficulties for the satellites and spacecraft orbiting the planet.
  • The study conducted between 1970 and 2020, said that the magnetic field weakened considerably in a large region stretching from Africa to South America, known as the ‘SAA’.
  • This area has grown and moved westward at a rate of around 20 km per year.

Its impact

  • The magnetic shield has an important role to play in keeping unwanted radiation away as well as helping determine the location of magnetic poles.
  • Even though unlike global warming or any weather change, this anomaly doesn’t directly impact human lives, it could actually bring on a change in the way we access technology.
  • The reversal and apparent shift, which could keep extending could actually impact satellite and telecommunication system, which means that some of the internet and mobile phone functioning which depend on satellite signals can possibly get disrupted.
  • It could also affect the mapping and navigation systems in smartphones.
  • The weakening of earth’s magnetic field could also impact migratory movement.
  • Birds, animals- all those who migrate with the change in season depend on the earth’s mapping to move about can find it a little difficult.
  • This is only a possibility, but we don’t know the extent of the damage till now.

About the Van Allen Radiation Belt

  • A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet’s magnetic field.
  • The belts are located in the inner region of Earth’s magnetosphere. The belts trap energetic electrons and protons.
  • Earth has two such belts and sometimes others may be temporarily created.
  • Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays.
  • By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.

Also read:

Shifting north magnetic pole forces urgent navigation fix


Back2Basics: Swarm  Constellation

  • Swarm is a European Space Agency (ESA) mission to study the Earth’s magnetic field.
  • It is ESA’s first constellation of satellites for Earth observation.
  • The Swarm constellation consists of three satellites (Alpha, Bravo and Charlie) placed in two different polar orbits, two flying side by side at an altitude of 450 km and a third at an altitude of 530 km.

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What is Solar Minimum?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Solar minima and maxima

Mains level : Solar minima and maxima, its impact on space weather and earth

The sun is said to have gone into a state called the ‘solar minimum’ and is about to enter the deepest period of ‘sunshine recession’ as sunspots are virtually not visibly at all.

Practice question for Mains:

Q. What are Solar minima and maxima? Discuss its impact on space weather and the Earth.

What is a solar minimum and why is it happening now?

  • Sun has a cycle that lasts on average 11 years, and right now we are at the peak of that cycle.
  • Every 11 years or so, sunspots fade away, bringing a period of relative calm.
  • This is called the solar minimum. And it’s a regular part of the sunspot cycle.
  • While intense activity such as sunspots and solar flares subside during solar minimum, that doesn’t mean the sun becomes dull. Solar activity simply changes form.

What about Solar Maximum?

  • Solar minima and maxima are the two extremes of the Sun’s 11-year and 400-year activity cycle.
  • At a maximum, the Sun is peppered with sunspots, solar flares erupt, and the Sun hurls billion-ton clouds of electrified gas into space.
  • Sky watchers may see more auroras, and space agencies must monitor radiation storms for astronaut protection.
  • Power outages, satellite malfunctions, communication disruptions, and GPS receiver malfunctions are just a few of the things that can happen during a solar maximum.

What are its effects on Earth?

a) On space weather

  • The Solar wind from coronal holes will temporarily create disturbances in the Earth’s magnetosphere, called geomagnetic storms, auroras, and disruptions to communications and navigation systems.
  • The space weather during solar minimum will also affect Earth’s upper atmosphere on satellites in low Earth orbit changes.
  • This means that the Earth’s upper atmosphere will cool down which is generally heated and puffed up by ultraviolet radiation from the sun.
  • However, the heat at the upper atmosphere of our planet helps Earth to drag debris and keep the low Earth orbit clear of manmade space junk.
  • Apart from this, the solar minimum will change the space weather significantly which will lead to an increase in the number of galactic cosmic rays that reach Earth’s upper atmosphere.
  • These Galactic cosmic rays are high energy particles which are a result of distant supernova explosions and other violent events in the galaxy.

b) On astronauts

  • According to NASA the sun’s magnetic field weakens and provides less shielding from these cosmic rays during a solar minimum which will directly increase the threat to astronauts travelling through space.
  • This may cause health risks to astronauts travelling through space as the sun’s magnetic field weakens and provides less shielding from these cosmic rays.

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Super Cyclone Amphan and its threats

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Tropical Cyclones

Mains level : Rising events of Tropical Cyclone in India

The storm system in the Bay of Bengal, Amphan, developed into a super cyclone and is expected to make landfall along the West Bengal-Bangladesh coast very soon.

Realted PYQ:

Q. In the South Atlantic and South Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason? (CSP 2015)

(a) Sea Surface temperature are low
(b) Inter Tropical Convergence Zone seldom occurs
(c) Coriolis force is too weak
(d) Absence of land in those regions

Super Cyclone Amphan

  • Cyclone Amphan is a tropical cyclone formed over the Bay of Bengal that has intensified and likely to turn into a “super cyclonic storm (maximum wind speed is 224 kmph)”.
  • It has been named by Thailand.
  • Amphan is the equivalent of a Category 5 hurricane on the Saffir-Simpson Hurricane Wind Scale.
  • By the time it makes landfall in West Bengal, Amphan is expected to tone down into a category 4 Extremely Severe Cyclonic (ESC) storm with a wind speed of 165-175 kmph and gusting to 195 kmph.

What makes it a nightmare?

  • This is the first super cyclone to form in the Bay of Bengal after the 1999 super cyclone that hit Odisha and claimed more than 10,000 lives.
  • It is the third super cyclone to occur in the North Indian Ocean region after 1999 which comprises of the Bay of Bengal, the Arabian Sea and the northern part of the Indian Ocean.
  • The other two super cyclones were Cyclone Kyarr in 2019 and Cyclone Gonu in 2007.

Recent cyclones in the region

  • From 1965 to 2017, the Bay of Bengal and the Arabian Sea collectively registered 46 ‘severe cyclonic storms’.
  • More than half of them occurred between October and December.
  • Seven of them occurred in May and only two (in 1966 and 1976) were recorded in April, according to data from the IMDs cyclone statistics unit.
  • Cyclone Phailin in 2013 and the super cyclone of 1999 — both of which hit coastal Odisha — have been the most powerful cyclones in the Bay of Bengal in the past two decades in terms of wind speed.
  • Last year, Fani, which was an ESC made landfall in Odisha and ravaged the State, claiming at least 40 lives.

Back2Basics: Tropical Cyclones

  • Cyclones are formed over slightly warm ocean waters.
  • The temperature of the top layer of the sea, up to a depth of about 60 metres, need to be at least 28°C to support the formation of a cyclone.
  • This explains why the April-May and October-December periods are conducive for cyclones.
  • Then, the low level of air above the waters needs to have an ‘anticlockwise’ rotation (in the northern hemisphere; clockwise in the southern hemisphere).
  • During these periods, there is an ITCZ in the Bay of Bengal whose southern boundary experiences winds from west to east, while the northern boundary has winds flowing east to west.
  • This induces the anticlockwise rotation of the air.
  • Once formed, cyclones in this area usually move northwest. As it travels over the sea, the cyclone gathers more moist air from the warm sea and adds to its heft.

What strengthens them?

  • A thumb rule for cyclones is that the more time they spend over the seas, the stronger they become.
  • Hurricanes around the US, which originate in the vast open Pacific Ocean, are usually much stronger than the tropical cyclones in the Bay of Bengal, a relatively narrow and enclosed region.
  • The cyclones originating here, after hitting the landmass, decay rapidly due to friction and absence of moisture.

Grading of Cyclones

  • Tropical cyclones in the Bay of Bengal are graded according to maximum wind speeds at their centre.
  • At the lower end are depressions that generate wind speeds of 30 to 60 km per hour, followed by:
  1. cyclonic storms (61 to 88 kmph)
  2. severe cyclonic storms (89 to 117 kmph)
  3. very severe cyclonic storms (118 to 166 kmph)
  4. extremely severe cyclonic storms (167 to 221 kmph) and
  5. super cyclones (222 kmph or higher)

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[pib] River erosion in Ladakh Himalayas

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Himalayan rivers, Zanskar Padam

Mains level : Read the attached story

Indian researchers have studied rivers in Ladakh Himalaya, bringing out 35 thousand-year histories of river erosion and identified hotspots of erosion and wide valleys that act buffer zones.

Click here to read more about the Himalayan river systems and its orogeny

Erosion hotspot: Ladakh region

  • The Ladakh Himalaya forms a high altitude desert between Greater Himalayan ranges and Karakoram Ranges.
  • The Indus and its tributaries are major rivers flowing through the terrain.
  • The Zanskar River is one of the largest tributaries of the upper Indus catchment, draining orthogonally through highly deformed Zanskar ranges.

Zanskar: A major river in Ladakh

  • Two prominent tributaries of Zanskar River are the Doda and Tsrap Lingti Chu, which confluence at Padam village in the upper valley to form the Zanskar River.
  • Zanskar catchment was explored to understand the landform evolution in the transitional climatic zone, using morpho-stratigraphy and study of landforms like valley fill terraces, alluvial fans (triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt).

Zanskar Padam

  • Zanskar river makes a deep gorge in its lower reaches with the headwaters in upper Zanskar makes wide basin called as Padam.
  • The basin stores large amount of sediments in form of fans and river terrace deposits
  • The research suggested that the wide valley of Padam, with an area of 48 square km, in the upper Zanskar, has stored a vast amount of sediments in these landforms.
  • Thus Padam valley is a hotspot of sediment buffering in the Zanskar.

Sediment study reveals the erosion

  • The study suggested that most sediments were derived from Higher Himalayan crystalline that lies in the headwater region of Zanskar.
  • It was found out that dominant factors responsible for sediment erosion were deglaciation and Indian Summer Monsoon derived precipitation in the headwaters despite the presence of a geomorphic barrier (the deep, narrow gorge).

Significance of the study

  • The scientists have traced where the rivers draining Himalaya and its foreland erode the most and identify the zones that receive these eroded sediments and fill up.
  • The study will help understand river-borne erosion and sedimentation, which are the main drivers that make large riverine plains, terraces, and deltas that eventually become the cradle to evolving civilizations.
  • It will also help study the dynamics of devastating floods created by these Himalayan rivers in recent times.
  • Thus, the understanding of water and sediment routing becomes crucial while developing infrastructure and for other development works in the river catchment area.

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New list of names of tropical cyclones over north Indian Ocean

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Naming of Tropical Cyclones

Mains level : Tropical Cyclones

The India Meteorological Department (IMD) has released a new list containing 169 names of future tropical cyclones that would emerge in the Bay of Bengal and the Arabian Sea.

When is the name of a Tropical Cyclone declared?

  • Names are declared when TCs are diagnosed with maximum sustained surface wind-speed of 34 knots (62 kmph) or more as per Global Data Processing and Forecasting System (GDPFS) Manual of WMO.
  • Panel Members’ names will be listed alphabetically country-wise.

We can expect a statement based prelim question like – Which of the following criterion are followed while naming a tropical cyclone?

Who is involved in the naming of Tropic Cyclone?

  • Worldwide there are six regional specialised meteorological centres (RSMCs) and five regional Tropical Cyclone Warning Centres (TCWCs) mandated for issuing advisories and naming of tropical cyclones.
  • IMD is one of the six RSMCs to provide tropical cyclone and storm surge advisories to 13 member countries under WMO/ESCAP Panel.
  • The panel countries include Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates and Yemen.
  • RSMC, New Delhi is also mandated to name the Tropical Cyclones developing over the North Indian Ocean (NIO) including the Bay of Bengal and the Arabian Sea.

Since when did naming begin?

  • The WMO/ESCAP Panel on Tropical Cyclones (PTC) at its twenty-seventh Session held in 2000 in Muscat, agreed in principle to assign names to the tropical cyclones in the Bay of Bengal and the Arabian Sea.
  • After long deliberations among the member countries, the naming of the tropical cyclones over the north Indian Ocean commenced from September 2004.
  • This list contained names proposed by the eight member countries of WMO/ESCAP PTC, viz., Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand.

Why name Cyclones?

The naming of Tropical Cyclones (TC) helps the scientific community, disaster managers, media and general masses to-

  • identify each individual cyclone.
  • create awareness of its development.
  • remove confusion in case of simultaneous occurrence of TCs over a region
  • remember a TC easily
  • rapidly and effectively disseminate warnings to a much wider audience

Major criteria adopted for naming

  • The proposed name should be neutral to (a) politics and political figures (b) religious believes, (c) cultures and (d) gender
  • The name should be chosen in such a way that it does not hurt the sentiments of any group of the population over the globe
  • It should not be very rude and cruel in nature
  • The maximum length of the name will be eight letters
  • The Panel reserves the right to reject any name if any of the criteria above are not satisfied
  • The names of tropical cyclones over the north Indian Ocean will not be repeated. Once used, it will cease to be used again.

Back2Basics

Explained: Naming of cyclones

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Earth’s seismic noise levels

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Seismic noise

Mains level : Seismic activity and thier monitoring

Scientists at the British Geological Survey (BGS) reported a change in the Earth’s seismic noise and vibrations amid the coronavirus lockdown. This change has been monitored through a space-based seismograph.

Ever heard of space-based monitoring of seismic activities?  This topic creates a scope for potential prelims question…

What is seismic noise?

  • In geology, seismic noise refers to the relatively persistent vibration of the ground due to a multitude of causes.
  • It is the unwanted component of signals recorded by a seismometer– the scientific instrument that records ground motions, such as those caused by earthquakes, volcanic eruptions, and explosions.
  • This noise includes vibrations caused due to human activity, such as transport and manufacturing, and makes it difficult for scientists to study seismic data that is more valuable.
  • Apart from geology, seismic noise is also studied in other fields such as oil exploration, hydrology, and earthquake engineering.

How are vibrations generated?

  • We measure ground vibrations from earthquakes using seismometers.
  • These are incredibly sensitive so they also pick up other sources of vibration too, including human activity, such as road traffic, machinery and even people walking past.
  • All these things generate vibrations that propagate as seismic waves through the Earth.

Reasons for the decline

  • Due to the enforcement of lockdown measures around the world to tackle the novel coronavirus pandemic, the Earth’s crust has shown reduced levels of vibration.

How do the reduced noise levels help scientists?

  • The seismic noise vibrations caused by human activity are of high frequency (between 1-100 Hz), and travel through the Earth’s surface layers.
  • Usually, to measure seismic activity accurately and reduce the effect of seismic noise, geologists place their detectors 100 metres below the Earth’s surface.
  • However, since the lockdown, researchers were able to study natural vibrations even from surface readings, owing to lesser seismic noise.
  • Due to lower noise levels, scientists are now hoping that they would be able to detect smaller earthquakes and tremors that had slipped past their instruments so far.

 

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What are Primordial Black Holes (PBH)?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Primordial Black Holes, Big Bang

Mains level : Black Holes

A scientist duo from Pune has studied primordial black holes that were born as a result of a tiny bump in the potential energy levels of the universe, at a time when it was expanding rapidly.

Strange space events are known to be the favourites of UPSC 🙂

Primordial Black Holes (PBH)

  • PBH are a hypothetical type of black hole that formed soon after the Big Bang
  • It is believed that they are formed as a result of collapsing radiations as opposed to the collapse of massive stars, which is the case of any other black holes.
  • PBH can be massively large as 3000kms or be extremely tiny like nucleus of an atom.

What did the study conclude?

  • The study has confirmed that this marginal rise in potential energy resulted in birth of several PBHs and also emitted very powerful gravitational waves.
  • Approximately 14 billion years ago before the commencement of the Hot Big Bang phase, the very young universe was found to be active and expanding at a highly accelerated rate.
  • This exponential growth in its size was fuelled by the presence of uniform energy field and density as the universe passed through the Cosmic Inflation phase.
  • According to the scientists, as time passes, this uniform energy prevailing in the Inflation Field wanes out.
  • As a result, the universe resumes its normal decelerating rate.

Expansion of universe

  • Gravity is normally attractive in nature. The PBH did undergo rapid expansion due to the Inflation field which contrarily possessed repulsive gravity.
  • This pushed the universe to expand at a much faster rate than normal.
  • The universe had expanded to nearly 10^27 times its original size, that too, within just fraction of a second by the time Cosmic Inflation phase concluded.
  • Thereafter, the remnant energy possessed by this gravitational force got converted mainly into photons (light) in addition to protons, electrons, neutrons and other particles.
  • As the universe continued to grow exponentially during the Cosmic Inflation phase, it sent across tiny quantum jitters.
  • These fluctuations, released in a specific fashion, when sufficiently large, slowly give birth to galaxies and stars. Among those that were significantly large, helped form PBHs.

 

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[pib] Ionospheric based monitoring of large earthquakes

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Ionosphere, CIP

Mains level : Relation between atmosphere and seismic activity

Scientists of Indian Institute of Geomagnetism (IIG) an autonomous institution of the DST have extensively studied the signatures of recent large earthquakes into the ionosphere with an ambitious aim to derive the seismic source characteristics from the ionosphere.

CLAIMS

  • The research is a part of the interdisciplinary program ‘Coupled Lithosphere-Atmosphere- Ionosphere-Magnetosphere System (CLAIMS)’ of IIG.
  • CLAIMS focuses on energy transfer to the atmosphere during solid Earth processes such as earthquakes as well as tsunamis.

Key terms: Co-seismic Ionospheric Perturbations (CIP)

  • In general, the Earth crust uplift during an earthquake produces compressional (i.e. pressure) waves in the overlying atmosphere.
  • These waves propagate upward in the region of exponentially decreasing atmospheric neutral density, and thus, wave amplitude increase with atmospheric heights.
  • On arrival at ionospheric heights, the waves redistribute ionospheric electron density and produce electron density perturbations (disruption) known as CIP.

Objective of CLAIMS

  • The spatial distribution of near field co-seismic Ionospheric perturbations (CIP) associated with this event could reflect well the ground deformation pattern evolved around the epicentre.
  • These CIPs were derived using the Global Positioning System (GPS) measured Total Electron Content (TEC).
  • The CIP distribution was estimated at Ionospheric piercing point (IPP) altitude.

Other factors affecting CIP

The major effective non-tectonic forcing mechanisms at ionospheric altitudes are the-

  1. orientation between the ambient geomagnetic field and seismic induced neutral wave perturbations.
  2. orientation between the moving satellite line of sights and the wave perturbations.
  3. ambient ionospheric electron density gradient.

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Ionosphere

  • The ionosphere is the ionized part of Earth’s upper atmosphere, from about 60 km to 1,000 km altitude.
  • It is a region that includes the thermosphere and parts of the mesosphere and exosphere.
  • It is ionized by solar radiation.

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Pink Supermoon/ Paschal Moon

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Pink Supermoon

Mains level : NA

A supermoon is all scheduled to show up in the sky on April 7. It would be the biggest and brightest full moon of 2020.

Pink Supermoon

  • According to NASA, a supermoon takes place when a full moon is at its closest to the Earth.
  • When the full moon appears at perigee (closest point from the earth) it is slightly brighter and larger than a regular full moon — and that is what we call a “supermoon.”
  • They are called Supermoons because they are 7 per cent bigger and 15 per cent brighter, compared to an average full Moon.
  • The moon will not be originally pink in colour. It got its name from the pink wildflowers – Wild Ground Phlox – that bloom in the spring and are native to North America.
  • It is also called Paschal moon because, in the Christian calendar, this is used to calculate the date for Easter – the first Sunday after the Paschal Moon is Easter Sunday.

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Earth’s spin has slowed over time

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Torreites sanchezi, Leap Year

Mains level : Evolution in the spin of earth and various factors affecting it

 

Earth spun 372 times a year 70 million years ago, compared to the current 365. This means the day was 23½ hours long, compared to 24 today.

Faster Earth in the olden days

  • It has long been known that Earth’s spin has slowed over time.
  • Previous climate reconstructions, however, have described long-term changes over tens of thousands of years.
  • The new study looked at daily and annual variations in the mollusc shell.

About the Mollusc

  • A mollusc is an invertebrate of a large phylum which includes snails, slugs, mussels, and octopuses. They have a soft unsegmented body and live in aquatic or damp habitats, and most kinds have an external calcareous shell.
  • The ancient mollusc, Torreites Sanchez, belonged to an extinct group called rudist clams.
  • At 70 million years ago, it belonged to the Late Cretaceous — it was around the time this epoch ended, some 65 million years ago, that dinosaurs went extinct.

How did researchers conclude this variation?

  • Torreites sanchezi grew very fast, laying down daily growth rings.
  • Using lasers on a single individual, scientists sampled tiny slices and counted the growth rings accurately.
  • This allowed them to determine the number of days in a year 70 million years ago, and more accurately calculate the length of a day.

Significance of the research

  • It is important to note that the period of Earth’s orbit has remained the same. In other words, one year 70 million years ago was as long as one year today.
  • However, if there were a calendar then, the year would have been 372 “days” long, with each “day” half-an-hour shorter than one day today.
  • Today, Earth’s orbit is not exactly 365 days, but 365 days and a fraction, which is why our calendars have leap years, as a correction.

The Moon’s retreat

  • Friction from ocean tides, caused by the Moon’s gravity, slows Earth’s rotation and leads to longer days.
  • And as Earth’s spin slows the Moon moves farther away at 3.82 cm per year.
  • If this rate is projected back in time, however, the Moon would be inside the Earth only 1.4 billion years ago.
  • This new measurement, in turn, informs models of how the Moon formed and how closes it has been to Earth over their 4.5-billion-year gravitational relationship.

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[pib] Effects of Himalayan slip on its Hydrology

Researchers from the Indian Institute of Geomagnetism have found the mighty Himalayas subside and move up depending on the seasonal changes in groundwater.

Tectonic activity and groundwater

  • The Himalayan foothills and the Indo-Gangetic plain are sinking because its contiguous areas are rising due to tectonic activity associated with landmass movement or continental drift.
  • The new study shows that subsidence and uplift are found to be associated with seasonal changes in groundwater, apart from the normal, common reasons.
  • Water acts as a lubricating agent, and hence when there is water in the dry season, the rate of the slip of the fault in this region is reduced.
  • In the Himalaya, seasonal water from glaciers, as well as monsoon precipitation, plays a key role in the deformation of the crust and the seismicity associated with it.
  • The subsidence rate is associated with groundwater consumption.

Findings of the study

  • The researchers have made the combined use of GPS and Gravity Recovery And Climate Experiment (GRACE) data, which has made it possible for them to quantify the variations of hydrologic mass.
  • The GRACE satellites, launched by the US in 2002, monitor changes in water and snow stores on the continents.
  • The combined data suggest a 12% reduction in the rate of the subsurface slip. This slip refers to how fast the fault is slipping relative to the foot and hanging wall.
  • The slip occurs at the Main Himalayan Thrust (MHT), due to hydrological variations and human activities, over which there is the periodic release of accumulated strain.

About GRACE Mission

  • The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center.
  • Twin satellites took detailed measurements of Earth’s gravity field anomalies from its launch in March 2002 to the end of its science mission in October 2017.
  • By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time.

 

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Explained: Cycle 25/ Solar Cycle

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Solar Cycle, Sunspots, Solar Dynamo

Mains level : Read the attached story

 

 

The sunspots identified by researchers from IISER Kolkata herald the start of a new solar cycle called Cycle 25.

What are Sunspots?

  • Sunspots are temporary phenomena on the Sun’s photosphere that appear as spots darker than the surrounding areas. They are relatively cooler spots on the Sun’s surface.
  • They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection.
  • Sunspots usually appear in pairs of opposite magnetic polarity with a leader and a follower.

What is Solar Cycle?

  • From our safe distance of about 148 million km, the Sun appears to be sedate and constant. However, huge solar flares and coronal mass ejections spew material from its surface into outer space.
  • They originate from sunspots, an important phenomenon that people have been following for hundreds of years. They originate deep within the Sun and become visible when they pop out.
  • Their number is not constant but shows a minimum and then rises up to a maximum and then falls again in what is called the solar cycle.
  • Every 11 years or so, the Sun’s magnetic field completely flips. This means that the Sun’s north and south poles switch places. Then it takes about another 11 years for the Sun’s north and south poles to flip back again.
  • So far, astronomers have documented 24 such cycles, the last one ended in 2019.

How do they occur?

  • Given the high temperatures in the Sun, matter exists there in the form of plasma, where the electrons are stripped away from the nuclei.
  • The Sun is made of hot ionized plasma whose motions generate magnetic fields in the solar interior by harnessing the energy of the plasma flows.
  • This mechanism is known as the solar dynamo mechanism (or magnetohydrodynamic dynamo mechanism).
  • Simply stated, it is a process by which kinetic energy of plasma motions is converted to magnetic energy, which generates the magnetised sunspots, giving rise to the solar cycle..
  • Because of the nature of the solar dynamo, the part of its magnetic field that gives rise to sunspots reverses direction when it moves from one solar cycle to another.
  • This can be inferred by observing when the relative orientation of the sunspot pairs flips.

Features

  • The solar cycle affects activity on the surface of the Sun, such as sunspots which are caused by the Sun’s magnetic fields. As the magnetic fields change, so does the amount of activity on the Sun’s surface.
  • One way to track the solar cycle is by counting the number of sunspots.
  • The beginning of a solar cycle is a solar minimum, or when the Sun has the least sunspots. Over time, solar activity—and the number of sunspots—increases.
  • The middle of the solar cycle is the solar maximum, or when the Sun has the most sunspots. As the cycle ends, it fades back to the solar minimum and then a new cycle begins.
  • Giant eruptions on the Sun, such as solar flares and coronal mass ejections, also increase during the solar cycle. These eruptions send powerful bursts of energy and material into space.

Impacts of Solar Cycle

  • This activity has effects on Earth. For example, eruptions can cause lights in the sky, called aurora, or impact radio communications. Extreme eruptions can even affect electricity grids on Earth.
  • Solar activity can affect satellite electronics and limit their lifetime.
  • Radiation can be dangerous for astronauts who do work on the outside of the International Space Station.
  • Forecasting of the solar cycle can help scientists protect our radio communications on Earth, and help keep satellites and astronauts safe.

Start of cycle 25

  • Following a weakening trend in activity over the last few cycles, there were predictions that the Sun would go silent into a grand minimum in activity, with the disappearance of cycles.
  • However, a team from IISER Kolkata has shown that there are signs that cycle 25 has just begun.
  • They used the data from the instrument Helioseismic and Magnetic Imager aboard NASA’s space-based Solar Dynamics Observatory for their calculations.

Why is this so important to us on earth?

  • After all the sunspots look small and are hardly even visible to us. Contrary to this, sunspot activity may be correlated with climate on earth.
  • In the period between 1645 and 1715, sun spot activity had come to a halt on the Sun – a phenomenon referred to as the Maunder minimum.
  • This coincided with extremely cold weather globally. So sunspots may have a relevance to climate on earth.
  • Such links are tenuous, but definitely solar activity affects space weather, which can have an impact on space-based satellites, GPS, power grids and so on.

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Solar Storms

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Solar Storms

Mains level : Solar storms and their impact on Earth

 

According to a research, sudden releases of high-energy particles from the sun, called solar storms, can mess with the navigational ability of gray whales, causing them to strand on land.

Solar storms

  • Solar storms are a variety of eruptions of mass and energy from the solar surface.
  • Flares, prominences, sunspots, coronal mass ejections are the common harbingers of solar activity, as are plages and other related phenomena seen at other wavelengths.

Impact on Whales

  • Solar storms have the potential to modify geomagnetic field and disrupt magnetic orientation behaviour of animals, hampering their navigation during long periods of migration.
  • They disrupt earth’s magnetic field — and the whales’ navigational sense.
  • The radio frequency noise created by the solar outburst affects the whales’ senses in a way that prevents them from navigating at all.

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Yongle Blue Hole (YBH)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Yongle Blue Hole (YBH)

Mains level : Signifcance of Blue Holes

 

Carbon more than 8,000 years old has been found inside the world’s deepest blue hole — the Yongle Blue Hole (YBH).

Yongle Blue Hole (YBH)

  • The deepest known marine cavern is the Yongle blue hole, which measures roughly 300 metres from top to bottom.
  • Blue holes are marine caverns filled with water and are formed following dissolution of carbonate rocks, usually under the influence of global sea level rise or fall.
  • Its waters are mostly isolated from the surrounding ocean and receive little fresh water from rainfall, making it a rare spot to study the chemistry of oxygen-deprived marine ecosystems.
  • What distinguishes them from other aquatic caverns is that they are isolated from the ocean and don’t receive fresh rainwater.
  • They are generally circular, steep-walled and open to surface.

Significance of YBH

  • YBH has a depth of 300 metres, far deeper than the previously recorded deepest blue hole, Dean’s Blue Hole in Bahamas, which had a depth of 202 metres.
  • However, like most blue holes, it is anoxic i.e. depleted of dissolved oxygen below a certain depth. This anaerobic environment is unfavorable for most sea life.
  • Such anoxic ecosystems are considered a critical environmental and ecological issue as they have led to several mass extinctions.
  • Concentrations of carbon, usually found in deep marine holes like YBH, provide a natural laboratory to study carbon cycling and potential mechanisms controlling it in the marine ecosystem.
  • The transition from aerobic to anaerobic environment adversely affects the biogeo-chemistry of the ocean.

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Why do we have Leap Years?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Leap Year and the science behind it

Mains level : Not Much

 

The year 2020 is a ‘leap year’, meaning the month of February will have 29 days instead of 28, and the total number of days will be 366 instead of 365. This was also the case in 2016, and 2024 will again be a leap year.

Leap Years

  • A calendar is meant to correspond to the Earth’s seasons.
  • For this, the number of days in a calendar needs to match the time required by the Earth to orbit the Sun.
  • The time required by the Earth to complete its orbit around the Sun is approximately 365.242 days. But years are usually only 365 days.
  • To adjust for the extra 0.242 days in the orbital period, which becomes almost one full day in four years, the calendar adds an extra day once every four years.
  • This approximates the time to 365.25 days, which is close to the actual 365.242 days.

But is that not inaccurate?

  • Yes, it is. And further adjustments are made to the Gregorian calendar, the calendar we follow today.
  • The Gregorian calendar was introduced in 1582. Before that, the calendar followed was the Julian calendar, introduced in 45 BC.
  • The calendars were different in their treatment of leap years.
  • The Julian calendar had leap days every four years, but since it still did not accurately conform to the Earth’s precise orbit time, it kept falling behind with respect to natural seasons over the centuries.
  • By the 16th century, the Julian calendar had fallen out of tune with the natural seasons by almost 10 days.
  • To correct this discrepancy, Pope Gregory XIII in 1582 decreed that the day of October 4 that year would be followed directly by October 15 – thus covering up the error.
  • The Pope also modified the leap year system in the Julian calendar. That new system came to be known as the Gregorian calendar.

What is the new system?

  • In the Gregorian calendar, a century year (a year ending with 00) is not a leap year, even though it is a multiple of 4. Thus, the year 2100 will not be a leap year.
  • But even this does not provide total accuracy. To ensure that, some century years remain leap years. In the Gregorian calendar, leap years include those century years which are exactly divisible by 400.
  • Thus, 2000 remained a leap year even though it ended with 00.
  • The Gregorian calendar reduces the margin of error under the Julian calendar, thus keeping days more in tune with seasons.

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Eruption of Taal Volcano

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Taal Volcano

Mains level : Volcanism and its impact

 

In the Philippines, a volcano called Taal on the island of Luzon; 50 km from Manila has recently erupted.

Taal Volcano

  • Taal is classified as a “complex” volcano. Taal has 47 craters and four maars (a broad shallow crater).
  • It is situated at the boundaries of two tectonic plates — the Philippines Sea Plate and the Eurasian plate — it is particularly susceptible to earthquakes and volcanism.
  • A complex volcano, also called a compound volcano, is defined as one that consists of a complex of two or more vents, or a volcano that has an associated volcanic dome, either in its crater or on its flanks.
  • Examples include Vesuvius, besides Taal.
  • The Taal volcano does not rise from the ground as a distinct, singular dome but consists of multiple stratovolcanoes (volcanoes susceptible to explosive eruptions), conical hills and craters of all shapes and sizes.

Threats posed

  • Taal’s closeness to Manila puts lives at stake. Manila is a few tens of kilometres away with a population of over 10 million.
  • The volcano is currently at alert level 4, which means that a “hazardous eruption” could be imminent within a few hours to a few days.
  • Hazardous eruptions are characterised by intense unrest, continuing seismic swarms and low-frequency earthquakes.

Earlier records of eruption

  • Taal has erupted more than 30 times in the last few centuries. Its last eruption was on October 3, 1977.
  • An eruption in 1965 was considered particularly catastrophic, marked by the falling of rock fragments and ashfall.
  • Before that, there was a “very violent” eruption in 1911 from the main crater. The 1911 eruption lasted for three days, while one in 1754 lasted for seven months.
  • Because it is a complex volcano with various features, the kinds of eruption too have been varied. An eruption can send lava flowing through the ground, or cause a threat through ash in the air.

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Private: Iron-snow on Earth’s innermost layer

  • The Earth’s deepest layer, the inner core, is capped by snow made of tiny particles of iron, which are much heavier than the snowflakes seen in the atmosphere.
  • According to the study the iron-snow falls from the molten outer core and piles up on top of the inner core, creating stacks up to 200 miles thick which cover the innermost layer of the planet.
  • Based on these findings, the study proposed the iron snow-capped core as an explanation for these aberrations.
  • With new data from experiments on core-like materials, the scientists found that crystallisation was possible and that about 15 per cent of the lowermost outer core could be made of iron-based crystals.
  • Researchers said these could eventually fall down the liquid outer core and settle on top of the solid inner core.
  • The slurry-like composition of the snow pack slows the seismic waves in such a way that the variation in snow pile size — thinner in the eastern hemisphere and thicker in the western — affected the speed of the waves.

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Annular Solar Eclipse

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Solar Eclipse and related terms

Mains level : Not Much

The last solar eclipse of this year will take place on December 26, which will fall over the eastern hemisphere of the Earth and be visible from most parts of India.

What is an annular solar eclipse?

  • An eclipse happens when the moon while orbiting the Earth comes in between the sun and the Earth, due to which the moon blocks the sun’s light from reaching the Earth, causing an eclipse of the sun or a solar eclipse.
  • According to NASA, people who are able to view the total solar eclipse are in the centre of the moon’s shadow as and when it hits the Earth.
  • There are three types of eclipses: one is a total solar eclipse, which is visible only from a small area on Earth. A total solar eclipse happens when the sun, moon and Earth are in a direct line.
  • The second type of a solar eclipse is a partial solar, in which the shadow of the moon appears on a small part of the sun.

Annular Solar Eclipse

  • The third kind is an annular solar eclipse, which happens when the moon is farthest from the Earth, which is why it seems smaller.
  • In this type of an eclipse, the moon does not block the sun completely, but looks like a “dark disk on top of a larger sun-colored disk” forming a “ring of fire”.
  • Furthermore, during a solar eclipse the moon casts two shadows on the Earth, the first one is called the umbra, which gets smaller as it reaches the Earth.
  • The second one is called the penumbra, which gets larger as it reaches the Earth.
  • According to NASA, people standing in the umbra see a total eclipse and those standing in the penumbra see a partial eclipse.

Why study of solar eclipse is crucial?

  • One of the reasons that NASA studies solar eclipses is to study the top layer of the sun called the corona.
  • During an annular eclipse, NASA uses ground and space instruments to view this top layer when the sun’s glare is blocked by the moon.

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Cyclone Pawan

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Cyclone Pawan

Mains level : Reason for increased cyclonic activities

With the formation of cyclone Pawan recently in the southwest Arabian Sea, the total number of cyclones in the North Indian Ocean region this year has reached the record eight.

Highest nos. of Cyclones this year

  • This is the highest number of cyclones in a single year since 1976, when nine cyclonic storms had formed in the region, according to data from the IMD.
  • This record might still be equalled as the IMD is tracking another depression in the east central Arabian Sea, though the system has weakened from a deep depression and is likely to de-intensify further in the coming days.
  • The Arabian Sea has seen a lot of cyclonic activity in 2019.
  • Five of the eight cyclones this year formed in this region, the highest in the past 117 years. Four of these were severe cyclones, which last occurred in 1902.
  • Only one of these cyclones, Maha, had an impact on the mainland, with heavy rainfall in Gujarat and Maharashtra. The rest of the cyclones formed, developed and dissipated in the sea.

Intense cyclones have increased

  • Six of the cyclones this year were of the ‘Severe’ or ‘Higher’ category.
  • While Cyclone Kyarr in October reached super cyclone intensity with wind speeds in excess of 250 kilometres per hour (km/hr).
  • Cyclone Fani in April-May and Cyclone Maha in October were of the ‘Extremely Severe’ category, with wind speeds greater than 200 km/hr.
  • Cyclone Vayu, Cyclone Hikaa and Cyclone Bulbul were of the ‘Very Severe’ category.
  • There were six ‘Severe’ cyclones in 2018 as well.
  • The last time there were more than five ‘Severe’ cyclones in two consecutive years was 1976-77 when seven and five ‘Severe’ cyclones formed respectively, according to IMD data.

What enhanced cyclonic activity?

  • The reason could be the active phases of both, the Indian Ocean Dipole and Madden Julian Oscillation phenomena.
  • The second could be global warming, which has led to warmer-than-usual temperatures on the surface of seas and oceans.
  • This provides the perfect conditions for the formation of low pressure areas which can intensify into depressions and further into cyclones.
  • In September, the World Meteorological Organization (WMO) had said that the world will be witness to warmer-than-usual surface and sea temperatures in the latter part of 2019.
  • It had also said that this was a clear sign of global warming in the absence of the El Nino phenomenon, which had ended in August.
  • Also according to the WMO, the leaning towards above normal temperatures was particularly strong in tropical and sub-tropical regions like India.
  • This could mean favourable conditions for the formation of cyclones in the Indian Ocean region as this is also the usual cyclone period.

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Explained: Naming of cyclones

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Species in news: Pliosaur

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Pliosaur

Mains level : NA


Pliosaurs

  • Over 150 million years ago, enormous reptiles swam the Jurassic oceans.
  • The largest aquatic carnivorous reptiles that have ever lived, they are often dubbed “sea monsters”.
  • Scientifically, they are placed in the suborder Pliosauroidea, whose members are called pliosaurs.
  • Interest in these giants has been revived with the recent discovery of their bones in a cornfield in the Polish village of Krzyzanowice. Remains of pliosaurs are rare in Europe.

What makes them special?

  • They measured over 10 metres in length and could weigh up to several dozen tons.
  • They had powerful, large skulls and massive jaws with large, sharp teeth.
  • Their limbs were in the form of fins.

Swietokrzyskie Mountains

  • The Swietokrzyskie Mountains are a mountain range in central Poland.
  • In the Jurassic era, the Swietokrzyskie Mountains area is believed to have been an archipelago of islands, where there were warm lagoons and shallow sea reservoirs, home to the marine reptiles discovered by the palaeontologists.
  • The locality where the remains were discovered is considered to be rich in the fossils of coastal reptiles. Researchers now hope to find more remains in the coming months.

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Places in news: Danakil Depression

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Danakil Depression

Mains level : NA


  • Microbes are known to survive almost anywhere. Scientists now believe that Danakil depression in Ethiopia is an exception.
  • New research has pointed out that bubbling pools of water and mounds of salt covering its landscape — that is too daunting even for these microorganisms.

Danakil Depression 

  • The Danakil Depression in northeastern Ethiopia is one of the world’s hottest places, as well as one of its lowest, at 100 metres below sea level.
  • At the northern end of the Great Rift Valley, and separated by live volcanoes from the Red Sea, the plain was formed by the evaporation of an inland water body.
  • All the water entering Danakil evaporates, and no streams flow out from its extreme environment. It is covered with more than 10 lakh tonnes of salt.
  • Now, a new study says that active and naturally occurring life cannot be sustained at Danakil.
  • It identifies two barriers: magnesium-dominated brines that cause cells to break down; and an environment having simultaneously very low pH and high salt, a combination that makes adaptation highly difficult.

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Explained: Daylight Saving Time (DST)

Note4Students

From UPSC perspective, the following things are important :

Prelims level : DST

Mains level : DST and its significance


Context

  • Clocks in Europe went back an hour on Sunday, signalling the end of Daylight Saving Time (DST) this year. The same will happen with clocks in the United States next week.
  • In the Southern Hemisphere, the opposite has happened.
  • Thus, clocks have gone ahead by an hour — in New Zealand and in Australia.

Daylight Saving Time (DST)

  • DST is the practice of setting the clocks forward one hour from standard time during the summer months, and back again in the fall, in order to make better use of natural daylight.
  • It is in use during the period from spring to autumn (or fall), when Europe and the United States get an extra hour of daylight in the evening.

When did the system of putting clocks forward and back start?

  • The idea of fixing clocks to save energy and to make the day seem longer than it is, is over 200 years old, but its sustained implementation took longer.
  • Written accounts suggest that a group of Canadians in Port Arthur (Ontario) were the first to adopt the practice on July 1, 1908, setting their clocks an hour ahead. Other parts of Canada followed suit.
  • In April 1916, during World War I, with Europe facing severe coal shortages, Germany and Austria-Hungary introduced DST to minimize the use of artificial lighting.
  • Many other countries on both the warring sides followed suit. The US introduced it in May 1916, and has stuck with it ever since.

Why use DST?

  • No daylight is of course, actually ‘saved’ — rather, the idea is to make better use of daylight.
  • So when it is autumn (or fall) in the Northern Hemisphere, and days are typically beginning to become shorter and nights longer, clocks are moved back an hour.
  • The rationale behind setting clocks ahead of standard time during springtime was to ensure that clocks showed a later sunrise and a later sunset — in effect, a longer evening daytime.
  • Individuals were expected to wake up an hour earlier than usual, and complete their daily work routines an hour earlier.
  • The governments decide to in effect transfer an hour of daylight from evening to morning, when it is assumed to be of greater use to most people.

Who uses DST?

  • Countries around the equator (in Africa, South America, and southeast Asia) do not usually follow DST; there isn’t much variation in the daylight they receive round the year in any case.
  • India does not have a DST, even though there are large parts of the country where winter days are shorter.
  • Most Gulf countries do not use DST — during the holy month of Ramzan, this could mean delaying the breaking of the fast for longer.
  • Morocco has DST, but suspends it during Ramzan. However, Iran has DST, and stays with it even during Ramzan.
  • Countries in East Asia and Africa mostly do not have a system of DST.

DST across the world

  • Dates for this switch, which happens twice a year (in the spring and autumn) are decided beforehand.
  • By law, the 28 member states of the EU switch together — moving forward on the last Sunday of March and falling back on the last Sunday in October.
  • In the US, clocks go back on the first Sunday of November.
  • Russia experimented with having permanent DST in 2011, but that created a situation in which it was dark at midday at some places.
  • So in 2014, it returned to switching from DST to standard time in the autumn.

What is the change with respect to Indian time?

  • Now that DST has ended in Europe and clocks have gone back an hour, the time difference between London and India is five and a half hours (and that between Paris or Berlin and India is four and a half hours).
  • Britain is now on Greenwich Mean Time (GMT); until Saturday when it was on DST or British Summer Time (BST).
  • Earlier the time difference between London and India was four and a half hours (three and a half hours for Paris or Berlin).

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Evolution of Universe after the Big Bang

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nobel Prize

Mains level : Big Bang Theory


Nobel Prize for Physics

  • This year’s Nobel Prize for Physics recognizes research that helps us understand our place in the universe.
  • Canadian-American cosmologist James Peebles, 84, won one-half of the Prize for his theoretical work helping us understand how the universe evolved after the Big Bang.
  • The other half went to Swiss astronomers Michel Mayor, 77, and Didier Queloz, 53, for their discovery of an exoplanet that challenged preconceived ideas about planets.

How the universe evolved

  • Modern cosmology assumes that the universe formed as a result of the Big Bang.
  • In decades of work since the 1960s, Peebles used theoretical physics and calculations to interpret what happened after.
  • His work is focused largely on Cosmic Microwave Background (CMB) radiation, which is electromagnetic radiation left over from the early universe once it had cooled sufficiently following the Big Bang.
  • Today, CMB can be observed with detectors.

Nobel Prize: It’s never too late

  • When it was observed for the first time in 1964 by radio astronomers Arnold Penzias and Robert Wilson —who would go on to be awarded the 1978 Physics Nobel — they were initially puzzled.
  • They learnt later that Peebles had predicted such radiation.
  • Peebles and colleagues have correlated the temperature of this radiation with the amount of matter created in the Big Bang.
  • This was a key step towards understanding how this matter would later form the galaxies and galaxy clusters.
  • From their work derives our knowledge of how mysterious the universe is — just 5% known matter and the rest unknown, as dark matter (26%) and dark energy (69%).

Exoplanets

  • The hunt for extraterrestrial life, if any exists, depends on finding habitable planets, mainly outside our Solar System.
  • Today, exoplanets are being discovered very frequently — over 4,000 are known — which is remarkable progress from three decades ago, when not even one exoplanet was known.
  • The first confirmed discoveries came in 1992, but these were orbiting not a star but the remains of one.
  • The planet discovered by Mayor and Queloz in 1995 is 50 light years away, orbiting the star 51 Pegasus that is similar to our Sun.

51 Pegasus

  • Called 51 Pegasus b, the exoplanet is not habitable either, but it challenged our understanding of planets and laid the foundation for future discoveries.
  • It is a gas giant comparable to Jupiter, yet it very hot, unlike icy cold Jupiter; 51 Pegagsus b is even closer to its star than Mercury is to our Sun.
  • Until then, gas giants were presumed to be cold, formed a great distance from their stars.
  • Today, it is accepted that these hot gas giants represent what Jupiter would look like if it were suddenly transported closer to the Sun.

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Role of Volcanoes in global warming

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Vulcanism, Deep Carbon Observatory (DCO)

Mains level : Role of Volcanoes in global warming


  • Human activity churns out up to 100 times more carbon each year as all the volcanoes on Earth, says a decade-long study Deep Carbon Observatory (DCO).

Deep Carbon Observatory (DCO)

  • DCO is a 10-year global research collaboration of more than 1,000 scientists to understand the quantities, movements, forms, and origins of carbon in Earth.
  • The findings are part of estimations by the DCO scientists of the Earth’s immense interior carbon reservoirs, and how much carbon the deep Earth naturally swallows and exhales.

Role of volcanoes

  • Scientists at the Deep Carbon Observatory (DCO) have found that even a handful of volcanic events have caused catastrophic releases of carbon, leading to a warmer atmosphere, acidified oceans, and mass extinctions.
  • Researchers from DCO’s DECADE (Deep Earth Carbon Degassing) subgroup found that volcanoes and volcanic regions outgassed an estimated 280-360 million tonnes of CO2 per year.
  • This includes the contribution from active volcanic vents, from the diffusing and widespread release of CO2 through soils, faults, and fractures in volcanic regions, volcanic lakes, and from the mid-ocean ridge system.

1. Particles of dust and ash

  • Volcanic ash or dust released into the atmosphere during an eruption shade sunlight and cause temporary cooling.
  • Larger particles of ash have little effect because they fall out of the air quickly. Small ash particles form a dark cloud in the troposphere that shades and cools the area directly below.
  • Most of these particles fall out of the atmosphere within rain a few hours or days after an eruption.
  • But the smallest particles of dust get into the stratosphere and are able to travel vast distances, often worldwide.
  • These tiny particles are so light that they can stay in the stratosphere for months, blocking sunlight and causing cooling over large areas of the Earth.

2. Sulfur

  • Often, erupting volcanoes emit sulfur dioxide into the atmosphere. Sulfur dioxide is much more effective than ash particles at cooling the climate.
  • The sulfur dioxide moves into the stratosphere and combines with water to form sulfuric acid aerosols.
  • The sulfuric acid makes a haze of tiny droplets in the stratosphere that reflects incoming solar radiation, causing cooling of the Earth’s surface.
  • The aerosols can stay in the stratosphere for up to three years, moved around by winds and causing significant cooling worldwide. Eventually, the droplets grow large enough to fall to Earth.

3. Greenhouse gases

  • Volcanoes also release large amounts of greenhouse gases such as water vapor and carbon dioxide.
  • The amounts put into the atmosphere from a large eruption doesn’t change the global amounts of these gases very much.
  • However, there have been times during Earth history when intense volcanism has significantly increased the amount of carbon dioxide in the atmosphere and caused global warming.

Contrasting to humans

  • For the past 100 years, humanity’s annual carbon emissions through the burning of fossil fuels and forests were 40 to 100 times greater than those from geologic sources such as all volcanic emissions, a/c to DECADE.

Degassing

  • About 400 of the 1500 volcanoes active since the last Ice Age 11,700 years ago are venting CO2 today, said DECADE.
  • Another 670 could be producing diffuse emissions, with 102 already documented.
  • Of these, 22 ancient volcanoes that have not erupted since the Pleistocene Epoch (2.5 million years ago to the Ice Age) are outgassing.
  • DECADE also confirmed that more than 200 volcanic systems emitted measurable volumes of CO2 between 2005 and 2017. Of these, several regions of degassing have been documented.
  • These include Yellowstone in the United States, the East African Rift, and the Technong volcanic province in China.

A fine balance

  • The quantity of carbon released from Earth’s mantle has been in relative balance with the quantity returned through the downward subduction of tectonic plates and other processes.
  • Any imbalance to the carbon cycle could cause rapid global warming, changes to the silicate weathering rate, changes to the hydrologic cycle, and overall rapid habitat changes that could cause mass extinction as the earth rebalanced itself.

Total carbon

  • The scientists also calculated that just two-tenths of one per cent of Earth’s total carbon — about 43,500 Gt — is above surface in the oceans, on land, and in the atmosphere.
  • The rest is subsurface, including the crust, mantle and core — an estimated 1.85 billion Gt in all.
  • While around 37,000 gt carbon (85.1 per cent) is in the deep ocean, 3,000 gt (6.9 per cent) lies in marine sediments.

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When did the Anthropocene Epoch begin on Earth?

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Geological time scale

Mains level : Debate over the epoch


  • A committee of geologists has now proposed to mark the start of the Anthropocene in the mid-20th century, based on a striking indicator: the widely scattered radioactive dust from nuclear bomb tests in the early 1950s.

A new human age

  • Human impacts are everywhere. Our societies have changed Earth so much that it’s impossible to reverse many of these effects.
  • Examples of how human societies are changing the planet abound — from building roads and houses, clearing forests for agriculture , to shrinking the ozone layer, driving species extinct, changing the climate and acidifying the oceans.etc.
  • Some researchers believe these changes are so big that they mark the beginning of a new “human age” of Earth history, the Anthropocene epoch.

When to mark as beginning?

  • Researchers debate the utility of picking a single time line in Earth’s geological record to mark the start of human impacts in the geological record.
  • Maybe the Anthropocene began at different times in different parts of the world.
  • For example, the first instances of agriculture emerged at different places at different times, and resulted in huge impacts on the environment, through land clearing, habitat losses, extinctions, erosion etc.
  • There are multiple beginnings, scientists need to answer more complicated questions — like when did agriculture begin to transform landscapes in different parts of the world?
  • This is a tough question because archaeologists tend to focus their research on a limited number of sites and regions and to prioritize locations where agriculture is believed to have appeared earliest.
  • To date, it has proved nearly impossible for archaeologists to put together a global picture of land use changes throughout time.

Global answers from local experts

  • To tackle these questions, collaboration was held among archaeologists, anthropologists and geographers to survey archaeological knowledge on land use across the planet.
  • They mapped the current state of archaeological knowledge on land use across the planet, including parts of the world that have rarely been considered in previous studies.

With onset of agriculture

  • Archaeologists reported that nearly half (42 per cent) of the regions had some form of agriculture by 6,000 years ago, highlighting the prevalence of agricultural economies across the globe.
  • Moreover, these results indicate that the onset of agriculture was earlier and more widespread than suggested in the most common global reconstruction of land-use history, the History Database of the Global Environment.
  • This is important because climate scientists often use this database of past conditions to estimate future climate change; according to our research it may be underestimating land-use-associated climate effects.
  • Hunting and foraging was generally replaced by pastoralism (raising animals such as cows and sheep for food and other resources) and agriculture in most places, though there were exceptions.
  • In a few areas, reversals occurred and agriculture did not simply replace foraging but merged with it and coexisted side by side for some time.

More deeper roots

  • Global archaeological data show that human transformation of environments began at different times in different regions and accelerated with the emergence of agriculture.
  • Nevertheless, by 3,000 years ago, most of the planet was already transformed by hunter-gatherers, farmers and pastoralists.
  • To guide this planet toward a better future, we need to understand how we got here.
  • The message from archaeology is clear. It took thousands of years for the pristine planet of long ago to become the human planet of today.
  • To build a more robust Earth science in the Anthropocene, the human sciences must play as central a role as the natural sciences do today.

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Anthropocene as Earth’s new epoch

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Hurricane Dorian

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Difference between a hurricane, a cyclone, and a typhoon

Mains level : Tropical Cyclones in India


  • The hurricane Dorian is to hit the east coast of Florida as a “major” hurricane, in Category 3 or possibly Category 4.

What do the categories mean?

  • Powerful winds are what define a hurricane, so they are named and classified based on how hard their winds are blowing.
  • To qualify as a hurricane, a storm must have sustained winds of 74 mph or more.
  • All hurricanes are dangerous, but some pack more punch than others.
  • So meteorologists try to quantify each storm’s destructive power by using the Saffir-Simpson scale placing it in one of five categories based on sustained wind speed:

Saffir-Simpson scale

Category 1, 74 to 95 mph:

  • These storms’ winds may knock down some trees and power lines and do a bit of damage to buildings.

Category 2, 96 to 110 mph:

  • These storms are likely to uproot many trees, disrupt electric power over wide areas and do significant roof and siding damage.

Category 3, 111 to 129 mph:

  • These are major storms that can take roofs off even well-constructed houses and knock out electric and water systems for days or weeks.
  • Roads will be blocked by falling trees and poles. Dorian is forecast to be at least this strong when it makes landfall.

Category 4, 130 to 156 mph:

  • These major storms do catastrophic damage, felling most trees and power poles and wrecking some buildings.
  • Affected areas may be uninhabitable for days or weeks afterward.

Category 5, 157 mph or more:

  • Storms this powerful are rare, and when they strike, they are immensely destructive.
  • Few structures will come through a direct hit unscathed, and a large percentage of frame buildings will be destroyed. Recovery may take weeks or months.

Back2Basics

What is the difference between a hurricane, a cyclone, and a typhoon?

  • The only difference between a hurricane, a cyclone, and a typhoon is the location where the storm occurs.
  • In the Atlantic and Northeast Pacific, the term “hurricane” is used.
  • The same type of disturbance in the Northwest Pacific is called a “typhoon” and “cyclones” occur in the South Pacific and Indian Ocean.
  • A tropical cyclone is a generic term used by meteorologists to describe a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation.

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Adratiklit boulahfa

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Adratiklit boulahfa

Mains level : Not Much


Adratiklit boulahfa

  • Scientists have described a new species of stegosaurus and dated it to 168 million years ago, which makes it the oldest known member of that group of dinosaurs ever known.
  • Named Adratiklit boulahfa, it is also the first stegosaurus to be found in North Africa.
  • Its remains were discovered in the Middle Atlas Mountains of Morocco.
  • The scientists believe it is not only a new species but also belongs to a new genus.
  • The name is derived from the words used by the Berber (an ethnic group indigenous to North Africa) for mountains (Adras), lizard (tiklit) and and the area where the specimen was found. (Boulahfa).

What makes it special?

  • The Adratiklit was armoured and herbivorous, and lived on the ancient supercontinent of Gondwana, which later split into Africa, South America, Australia and Antarctica.
  • Most stegosaurus remains so far have been found in the northern hemisphere.
  • However, this may not mean that stegosaurs were uncommon in Gondwana.
  • It may be due to the fact that Gondwana rock formations have been subject to far fewer excavations and detailed studies.

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Perseid Meteor Shower

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Read the attached story

Mains level : Not Much


What is Meteoric Shower?

  • On its journey around the Sun, the Earth passes through large swathes of cosmic debris.
  • The debris is essentially the remnants of comets — great frigid chunks of matter that leave behind dirty trails of rocks and ice that linger long after the comets themselves have passed.
  • As the Earth wades through this cloud of comet waste, the bits of debris create what appears from the ground to be a fireworks display in the sky — known as a meteor shower.

When does Perseid Meteor Shower occur?

  • Several meteor showers can be seen around the year.
  • Among the brightest and best known of them is the Perseid Meteor Shower, which has been active from July 17 onward, and can be seen until August 26.
  • The showers peaked on the night of Monday-Tuesday.
  • The Perseids occur as the Earth runs into pieces of cosmic debris left behind by the comet Swift-Tuttle.
  • The cloud of debris is about 27 km wide — and at the peak of the display, between 160 and 200 meteors streak through the Earth’s atmosphere every hour as the pieces of debris, travelling at some 2.14 lakh kph.

When to see them?

  • Meteors are best seen on a cloudless night, when the entire sky is visible, and when the Moon is not extremely bright.
  • Chances of a successful viewing are higher from locations far away from the lights of cities. Pollution and monsoon clouds make the Perseids difficult to view from India.
  • The showers peak when the Earth passes through the most dense part of the debris cloud.
  • Peaks can last for a few hours or several nights. They tend to be most visible after midnight and before dawn.
  • The showers should be seen with naked eyes; binoculars and telescopes narrow the field of vision.

The Swift-Tuttle Comet

  • The Perseids currently visible in the night sky are not due to the debris left behind by the comet Swift-Tuttle during its most recent pass, which happened in 1992.
  • This particular comet goes around the Sun once in 133 years, and the meteors now visible were left behind by the pass before the last one — or perhaps even earlier.

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Milky Way’s violent birth decoded

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Milky Way, Big Bang

Mains level : Formation of our solar system


  • The Milky Way, home to our sun and billions of other stars, merged with another smaller galaxy in a colossal cosmic collision roughly 10 billion years ago, scientists said based on data from the Gaia space observatory.

What is Milky Way?

  • The Milky Way is the galaxy that contains the Solar System, with the name describing the galaxy’s appearance from Earth.
  • It resembles to a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
  • Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610.

Its formation

  • The union of the Milky Way and the so-called dwarf galaxy Gaia-Enceladus increased our galaxy’s mass by about a quarter and triggered a period of accelerated star formation lasting about 2 to 4 billion years.
  • Galaxies of all types, including the Milky Way, began to form relatively soon after the Big Bang explosion that marked the beginning of the universe some 13.8 billion years ago.
  • But they were generally smaller than those seen today and were forming stars at a rapid rate.
  • Subsequent galactic mergers were instrumental in configuring galaxies existing now.

How was that verified?

  • A high-precision measurement of the position, brightness and distance of around a million stars within 6,500 light years of the sun was obtained by the Gaia space telescope.
  • It helped pinpoint stars present before the merger and those that formed afterward.
  • Certain stars with higher content of elements other than hydrogen or helium arose in the Milky Way and others with lower such content originated in Gaia-Enceladus owing to its smaller mass.
  • While the merger was dramatic and helped shape the Milky Way, it was not a star-destroying calamity.
  • This crash was big in cosmic terms, but if it was happening now, we could probably not even notice at a human or solar system level.

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Explained: How lightning strikes, and why it kills

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Lightening

Mains level : Lightening mechanism

  • Twenty-nine people have been killed by lightning over the past 36 hours in Bihar.

Deaths by Lightening

  • Lightning is the biggest contributor to accidental deaths due to natural causes.
  • A few years ago, over 300 people were reported killed by lightning in just three days — a number that surprised officials and scientists.
  • And yet, lightning remains among the least studied atmospheric phenomena in the country.
  • Just one group of scientists, at the Indian Institute of Tropical Management (IITM) in Pune, works full-time on thunderstorms and lightning.

What is lightning?

  • Lightning is a very rapid — and massive — discharge of electricity in the atmosphere, some of which is directed towards the Earth’s surface.
  • These discharges are generated in giant moisture-bearing clouds that are 10-12 km tall.
  • The base of these clouds typically lies within 1-2 km of the Earth’s surface, while their top is 12-13 km away.
  • Temperatures towards the top of these clouds are in the range of minus 35 to minus 45 degrees Celsius.

How does it strike?

  • As water vapour moves upward in the cloud, the falling temperature causes it to condense. Heat is generated in the process, which pushes the molecules of water further up.
  • As they move to temperatures below zero degrees celsius, the water droplets change into small ice crystals.They continue to move up, gathering mass — until they are so heavy that they start to fall to Earth.
  • This leads to a system in which, simultaneously, smaller ice crystals are moving up and bigger crystals are coming down.
  • Collisions follow, and trigger the release of electrons — a process that is very similar to the generation of sparks of electricity.
  • As the moving free electrons cause more collisions and more electrons, a chain reaction ensues.
  • This process results in a situation in which the top layer of the cloud gets positively charged, while the middle layer is negatively charged.
  • The electrical potential difference between the two layers is huge — of the order of a billion to 10 billion volts.
  • In very little time, a massive current, of the order of 100,000 to a million amperes, starts to flow between the layers.
  • An enormous amount of heat is produced, and this leads to the heating of the air column between the two layers of the cloud.
  • This heat gives the air column a reddish appearance during lightning. As the heated air column expands, it produces shock waves that result in thunder.

How does this current reach the Earth from the cloud?

  • While the Earth is a good conductor of electricity, it is electrically neutral.
  • However, in comparison to the middle layer of the cloud, it becomes positively charged.
  • As a result, about 15%-20% of the current gets directed towards the Earth as well.
  • It is this flow of current that results in damage to life and property on Earth.
  • There is a greater probability of lightning striking tall objects such as trees, towers or buildings.
  • This happens because air is a poor conductor of electricity, and electrons that are travelling through air seek both a better conductor and the shortest route to the relatively positively charged Earth’s surface.

When does lightening hit people?

  • Lightning rarely hits people directly — but such strikes are almost always fatal.
  • People are most commonly struck by what are called “ground currents”.
  • The electrical energy, after hitting a large object (such as a tree) on Earth, spreads laterally on the ground for some distance, and people in this area receive electrical shocks.
  • It becomes more dangerous if the ground is wet (which it frequently is because of the accompanying rain), or if there is metal or other conducting material on it.
  • Water is a conductor, and many people are struck by lightning while standing in flooded paddy fields.

How uncertain is its prediction?

  • Predicting a thunderstorm over a pinpointed location is not possible.
  • Nor is it possible to predict the exact time of a likely lightning strike.

Precautions to be taken

  • For reasons given above, taking shelter under a tree is dangerous.
  • Lying flat on the ground too, can increase risks.
  • People should move indoors in a storm; however, even indoors, they should avoid touching electrical fittings, wires, metal, and water.

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Arabian Sea Cyclones

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Arabian Sea Cyclones

Mains level : Tropical Cyclones in India and thier aftermath

  • Just over a month after the powerful cyclone Fani devastated large areas of Odisha, another cyclone is headed towards India, this time towards the Gujarat coast.

Arabian Sea cyclones

  • Though cyclones are common in the June, very few of them originate in the Arabian Sea. Most of them are found in the Bay of Bengal.
  • In the last 120 years for which records are available, just about 14% of all cyclonic storms, and 23% of severe cyclones, around India have occurred in the Arabian Sea.
  • Arabian Sea cyclones are also relatively weak compared to those emerging in the Bay of Bengal.
  • This, along with the fact that the Gujarat coastline, which is where most of the cyclones emerging in the Arabian Sea are headed, is not very densely populated.
  • This ensures that the damage potential of the cyclones on the western coast is comparatively low.

About Cyclone Vayu

  • Cyclone Vayu is a deep depression positioned around 250 km northwest of Aminidivi island in Lakshadweep and about 750 km southwest of Mumbai.
  • It is likely to generate winds of speed 110-120 km per hour. In contrast, winds associated with Fani had speeds of about 220 km per hour.
  • Vayu at its most powerful stage would only be categorised as a “severe cyclonic storm”, while Fani was an “extremely severe cyclonic storm”
  • It has almost satisfied the conditions for classification as a “super cyclone”.

Major Impact: It halts Monsoon

  • Cyclones are sustained by very strong low-pressure areas at their core. Winds in surrounding areas are forced to rush towards these low-pressure areas.
  • Vayu is likely to halt the northward progression of the monsoon for a few days.
  • The cyclone is expected to interfere with normal progression, by sucking all the moisture from the monsoon winds towards itself.
  • Similar low-pressure areas, when they develop near or over land, are instrumental in pulling the monsoon winds over the country as well.
  • But right now, the low-pressure area at the centre of the cyclone is far more powerful than any local system that can pull the monsoon winds moving northeast.

Implications

  • What this means is that the places where the monsoon has already reached would continue to get rain, mainly along the western coastline, but other areas would have to wait a little longer.

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Seawater from Ice Age tucked in rocks discovered in Indian Ocean

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Ice Age

Mains level : Read the attached story

Seawater from Ice Age

  • Scientists have discovered the remnants of seawater dating back to the Ice Age, tucked inside rock formations in the middle of the Indian Ocean.
  • Researchers from the University of Chicago in the U.S. made the discovery during a months-long scientific mission exploring the limestone deposits that form the Maldives.
  • The ship, the JOIDES Resolution, is specifically built for ocean science and is equipped with a drill that can extract cores of rock over a mile long from up to three miles beneath the seafloor.
  • The water in actual specimen was found to be 20,000-year-old as it was much saltier than normal seawater.

Importance of the study

  • Scientists are interested in reconstructing the last Ice Age because the patterns that drove its circulation, climate and weather were very different.
  • Understanding these patterns could shed light on how the planet’s climate will react in the future.

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Anthropocene as Earth’s new epoch

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Anthropocene epoch

Mains level : Geological time scale of Earth


  • Rising global temperatures, sea levels, depleting ozone layer and acidifying oceans are the result of human activity that has “distinctively” altered our planet.
  • Now, a team of scientists have voted to declare “Anthropocene” as a new chapter in the Earth’s geological history.

Anthropocene Epoch

  • Coined by Paul Crutzen and Eugene Stoermer in 2000 to denote the present geological time interval, Anthropocene has been used to describe humanity’s large impact on the environment.
  • The scientific community have intensely debated in the past the idea to formally define it as a geological unit within the Geological Time Scale.
  • Recently the 34-member Anthropocene Working Group (AWG), voted in favour of starting the new epoch.
  • The result builds on an informal vote taken at the 2016 International Geological Congress in Cape Town, and lays the groundwork for a formal proposal by 2021 to the International Commission on Stratigraphy.
  • The move signals the end of the Holocene epoch, which began 12,000 to 11,600 years ago.
  • The International Union of Geological Sciences needs to ratify the AWG formal proposal, before the new epoch can formally be recognised.

Global boundary Stratotype Section and Point

  • To show a clear transition from the Holocene, the scientists plan to identify a definitive geologic marker or ‘golden spike’.
  • It would be technically called a Global boundary Stratotype Section and Point (GSSP).
  • For this, the group will search for the marker from around the globe, including a cave in northern Italy, corals in the Great Barrier Reef and a lake in China.

Demarcation of an epoch is not so easy

  • To demonstrate a sedimentary record representing the start of the epoch, the researchers are likely to choose the radionuclides that came from atomic-bomb detonations from 1945 until the Limited Nuclear Test Ban Treaty of 1963.
  • The stratigraphic evidence indicates a time-transgressive Anthropocene with multiple beginnings rather than a single moment of origin.
  • Declaring a new epoch on the basis of the radionuclide signal alone impedes rather than facilitates scientific understanding of human involvement in Earth system change.

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Explained: Naming of cyclones

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Cyclone nomenclature

Mains level : Tropical Cyclones in India

Context

  • The newest cyclone to emerge out of the Bay of Bengal has been named Fani.
  • Before that, there were cyclones Hudhud in 2014, Ockhi in 2017 and Titli and Gaja in 2018.
  • Each Tropical Cyclone basin in the world has its own rotating list of names.
  • For cyclones in the Bay of Bengal and Arabian Sea, the naming system was agreed by eight member countries of a group called WMO/ESCAP and took effect in 2004.

Naming a Cyclone

  • There are five tropical cyclone regional bodies, i.e. ESCAP/WMO Typhoon Committee, WMO/ESCAP Panel on Tropical Cyclones, RA-I Tropical Cyclone Committee, RA-IV Hurricane Committee, and RA-V Tropical Cyclone Committee.
  • In general, tropical cyclones are named according to the rules at a regional level.
  • The WMO/ESCAP Panel on Tropical Cyclones at its twenty-seventh Session held in 2000 in Muscat, Oman agreed in principal to assign names to the tropical cyclones in the Bay of Bengal and Arabian Sea.
  • After long deliberations among the member countries, the naming of the tropical cyclones over north Indian Ocean commenced from September 2004.
  • Eight countries — India, Pakistan, Bangladesh, Maldives, Myanmar, Oman, Sri Lanka and Thailand participated in the panel and came up with a list of 64 names.
  • If public wants to suggest the name of a cyclone to be included in the list, the proposed name must meet some fundamental criteria, the RSMC website says.
  • The name should be short and readily understood when broadcast.
  • Further, the names must not be culturally sensitive and should not convey any unintended and potentially inflammatory meaning.

How naming takes place?

  • These countries submitted eight names each, which are arranged in an 8×8 table.
  • The first cyclone after the list was adopted was given the name in the first row of the first column — Onil, proposed by Bangladesh.
  • Subsequent cyclones are being named sequentially, column-wise, with each cyclone given the name immediately below that of the previous cyclone.
  • Once the bottom of the column is reached, the sequence moves to the top of the next column.
  • So far, the first seven columns have been exhausted, and Fani (again proposed by Bangladesh) is the top name in the last column.
  • The next cyclone will be named Vayu. The lists will wind up with Cyclone Amphan, whenever it comes.

When the lists end

  • After the 64 names are exhausted, the eight countries will propose fresh lists of names.
  • The lists for storms in the Atlantic and Eastern Pacific basins are, however, rotated.
  • Exception are, however, made in certain cases — if a storm causes excessive death and destruction, its name is considered for retirement and is not repeated; it is replaced with another name.

Why name cyclones?

  • It is generally agreed that appending names to cyclones makes it easier for the media to report on these cyclones, heightens interest in warnings, and increases community preparedness.
  • Names are presumed to be easier to remember than numbers and technical terms.
  • The practice of naming a storm/tropical cyclone would help identify each individual tropical cyclone.
  • The purpose of the move was also to make it easier for people to easily understand and remember the tropical cyclone/hurricane in a region, thus to facilitate disaster risk awareness, preparedness, management and reduction.
  • It does not confuse the public when there is more than one tropical cyclone in the same area.
  • Many agree that appending names to storms makes it easier for the media to report on tropical cyclones, heightens interest in warnings and increases community preparedness.
  • It’s easier and less confusing to say “Cyclone Titli” than remember the storm’s number or its longitude and latitude.

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Indian subcontinent’s collision with Asia boosted oxygen in world’s oceans

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Indian Plate

Mains level : Plate Tectonics Theory, Continental Drift Theory

  • When the landmass that is now the Indian subcontinent slammed into Asia about 50 million years ago, the oxygen in the world’s oceans increased, altering the conditions for life.

Impact of Indian Plate

  • The collision was already known to have changed the configuration of the continents, the landscape, global climate and more.
  • Researchers used microscopic seashells to create a record of ocean nitrogen over a period from 70 million years ago – shortly before the extinction of the dinosaurs – until 30 million years ago.

Nitrogen dating to find Oxygen level

  • Every organism on Earth requires “fixed” nitrogen – sometimes called “biologically available nitrogen.”
  • Nitrogen has two stable isotopes: 15N and 14N. In oxygen-poor waters, decomposition uses up “fixed” nitrogen.
  • This occurs with a slight preference for the lighter nitrogen isotope, 14N, so the ocean’s 15N-to-14N ratio reflects its oxygen levels.
  • That ratio is incorporated into tiny sea creatures called foraminifera during their lives, and then preserved in their shells when they die.
  • By analysing their fossils researchers were able to reconstruct the 15N-to-14N ratio of the ancient ocean, and therefore identify past changes in oxygen levels.

Why study oxygen?

  • Oxygen controls the distribution of marine organisms, with oxygen-poor waters being bad for most ocean life.
  • Many past climate warming events caused decrease in ocean oxygen that limited the habitats of sea creatures, from microscopic plankton to the fish and whales that feed on them.
  • Scientists trying to predict the impact of current and future global warming have warned that low levels of ocean oxygen could decimate marine ecosystems, including important fish populations.
  • The researchers found that in the 10 million years after dinosaurs went extinct, the 15N-to-14N ratio was high, suggesting that ocean oxygen levels were low.
  • They first thought that the warm climate of the time was responsible, as oxygen is less soluble in warmer water.
  • Global climate was not the primary cause of this change in ocean oxygen and nitrogen cycling.

Back2Basics

Movement of Indian Plate

  • Until roughly 140 million years ago, the Indian Plate formed part of the supercontinent Gondwana. It was a large island situated off the Australian coast, in a vast ocean.
  • The Tethys Sea separated it from the Asian continent till about 225 million years ago.
  • India is supposed to have started her northward journey about 200 million years ago at the time when Pangaea
  • India collided with Asia about 40-50 million years ago causing rapid uplift of the Himalayas.
  • The positions of India since about 71 million years till the present are shown in the Figure. It also shows the position of the Indian subcontinent and the Eurasian plate.
  • About 140 million years before the present, the subcontinent was located as south as 50◦ S. latitude. The two major plates were separated by the Tethys Sea and the Tibetan block was closer to the Asiatic landmass.
  • During the movement of the Indian plate towards the Asiatic plate, a major event that occurred was the outpouring of lava and formation of the Deccan Traps. This started somewhere around 60 million years ago and continued for a long period of time.
  • Note that the subcontinent was still close to the equator. From 40 million years ago and thereafter, the event of formation of the Himalayas took place.

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A new landscape on the horizon

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Various rift valleys mentioned in the newscard

Mains level : Intra-continental drifting

  • The recent scientific evidence has given a glimpse of the Earth’s changing contours—the African continent is splitting into two.

Africa is splitting

  • A place near Nairobi, Kenya had a large crack on the ground that appeared during an intense spell of rain and flooding.
  • The crack is 57 km long which is a locus of a future ocean formation.
  • Such an event happened 138 million years ago when the South American and African continents separated to give rise to the current South Atlantic Ocean.
  • All such signs on Earth’s surface point to a totally new landscape, which resembled how it looked like when it was formed 4.5 billion years ago one huge continent.
  • The farthest scientists can predict is that 250 million years from now all continents will unite again in one supercontinent and then will break apart again along the future rift systems.

Why such cracks?

  • At first, geologists thought the crack in Kenya was formed due to “erosion of soft soils infilling an old rift-related fault.
  • They later revealed that the crack had existed for quite some time, but was filled with ash from Mount Longmont, a volcano nearby.
  • The rain had washed away the ash to expose the crack. This triggered a debate whether the crack was a part of the East African Rift system.

Rift in systems

  • Rifts are the regions of extension of the crust and the lithosphere.
  • Continental changes take place at the boundaries of tectonic plates which are divisions of the uppermost layer of the Earth and swim around on the fluid mantle layer below it.
  • The extension may develop to a stage when two plates split apart, like in the example of the Red Sea and the Gulf of Aden. So continental rifts are potential places where new oceans are expected to form.
  • These plates periodically crash into each other, giving rise to earthquakes and volcanic eruptions when the intensity is less over short periods of time.
  • Over longer periods of time, they create all the geological and geographical features that we find on Earth like mountains, valleys and oceans.

Intra-continental drifting

  • One of these processes is an intra-continental rift system which acts between tectonic plates and can give rise to rift valleys or even new oceans.
  • The African Rift Valley, which is between Ethiopia and Kenya, is a classical example of this geodynamic process.
  • There, volcanism, earth-quakes and fracturing of the Earth’s surface result from the enormous forces that tear the eastern portion of the African continent apart.

 East African rift system

  • The East African rift system is more active in terms of volcanism and it is connected to the global ocean rift (ridge) system through the Afar-Red Sea—Gulf of Aden triple junction.
  • The Red Sea and the Gulf of Aden are the rifts along which two continents break apart and new oceanic flow is formed.
  • There are numerous rift systems around the world but the most active ones are the East African rift, Baikal rift, West Antarctic rift, Rio Grande rift, the Rhine Graben rift system in Europe and Shanxi rift system in China.
  • When such geographical features become prominent enough they reshape the way the planet looks.
  • The rifts undergo massive geological changes—shoulders of rifts grow and get eroded by rain and melting snow.
  • At the same time, the axial parts of rifts subside and get filled with sediments, which gets eroded from the shoulders.

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Malham Caves

Note4students

Mains Paper 1: Geography | Geographical features & their location

From UPSC perspective, the following things are important:

Prelims level: Malham Cave

Mains level: Features of the cave


News

  • Israel unveils world’s longest salt cave.

Malham Caves

  • Malham is one of 150 caves in Mount Sodom, at the southern part of the Dead Sea, that are made of pure salt.
  • Mount Sedom sits near the Dead Sea, a shrinking salt lake (and lowest point on Earth) that extends into Jordan, Israel and the occupied West Bank.
  • A large part of the cave’s interior is covered by a fine dust that blows in from the desert.
  • Massive slabs of salt, some amber-colored from dust and minerals, stick out in dramatic formations.
  • A thin slab appearing to have been sliced out is nicknamed “The Guillotine,” while twin slabs that look like a pair of tablets in a different hall have earned the title of “The Ten Commandments.”
  • Israeli researchers say they have discovered the world’s longest salt cave near the desert site where, according to the Bible, Lot’s wife was turned into a pillar of salt.

How old is it?

  • Radiocarbon dating suggests it’s about 7,000 years old, its many passages carved by the very occasional rain storms that pass through the region.
  • Even now, Malham continues to grow when water flows in and dissolves more of the salt.

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Solar tsunami can trigger the sunspot cycle

Note4students

Mains Paper 1: Geography | Salient features of World’s Physical Geography

From UPSC perspective, the following things are important:

Prelims level: Sunspots, Solar Tsunami

Mains level: Impact of Sunspots on mankind as a whole


News

  • A group of solar physicists suggests that a “solar tsunami” is at work that triggers the new sunspot cycle, after the old one ends.

Solar Dynamo

  • It is believed that the “solar dynamo” a naturally occurring generator which produces electric and magnetic fields in the sun is linked to the production of sunspots.
  • What kick-starts the 11-year sunspot cycle is not known.
  • The extreme temperature and pressure conditions that prevail some 20,000 km below the sun’s surface cause its material to form plasma consisting primarily of hydrogen and helium in a highly ionised state.
  • The plasma is confined with huge magnetic fields inside the sun.

What is Solar Tsunami?

  • The sun’s magnetic field, from which sunspots get generated, wraps around the sun in the east-west direction.
  • These magnetic fields behave like rubber bands on a polished sphere. They tend to slip towards the poles.
  • Holding these fields in their place requires that there is extra mass (plasma mass) pushing at the bands from higher latitudes.
  • Thus, a magnetic dam is formed which is storing a big mass of plasma.
  • At the end of a solar cycle, this magnetic dam can break, releasing huge amounts of plasma cascading like a tsunami towards the poles.
  • These tsunami waves travel at high speeds of about 1,000 km per hour carrying excess plasma to the mid-latitudes.
  • There they give rise to magnetic flux eruptions.
  • These are seen as the bright patches that signal the start of the next cycle of sunspots.

What are Sunspots?

  1. Sunspots are temporary phenomena on the Sun’s photosphere that appear as spots darker than the surrounding areas.
  2. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection.
  3. Sunspots usually appear in pairs of opposite magnetic polarity.

 Why study them?

  • The solar cycle and sunspot activity are intimately connected with space weather.
  • The model provides a sound physical mechanism supporting why we should expect the next sunspot cycle 25 to begin in the year 2020.
  • This is again followed by a strong increase in space weather shortly after the trigger of a series of new sunspots in that year.

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Scientists discover massive mountains under Earth’s crust

Note4students

Mains Paper 1: Geography | Changes in critical geographical features

From the UPSC perspective, the following things are important:

Prelims level: Interior of Earth

Mains level: Structure and feature of Earth’s interior


News

  • Scientists have discovered massive mountains in the Earth’s mantle, an advance that may change our understanding of how the planet was formed.

Earth’s Interior is different

  1. We often learn that the Earth has three layers: a crust, mantle and core, which is subdivided into an inner and outer core.
  2. While that is not wrong, it does leave out several other layers that scientists have identified within the Earth.

Earthquake data helps study

  1. In a study published in the journal, scientists used data from an enormous earthquake in Bolivia to find mountains and other topography on a layer located 660 km straight down, which separates the upper and lower mantle.
  2. Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”
  3. Data from earthquakes that are magnitude 7.0 or higher sends shockwaves in all directions that can travel through the core to the other side of the planet — and back again.

The transition zone

  1. The key data came from waves picked up after a magnitude 8.2 earthquake — the second-largest deep earthquake ever recorded — that shook Bolivia in 1994.
  2. The researchers examined a layer 410 km down, at the top of the mid-mantle “transition zone,” and they did not find similar roughness.
  3. The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and evolved.

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Shifting north magnetic pole forces urgent navigation fix

Note4students

Mains Paper 1: Geography | Changes in critical geographical features

From the UPSC perspective, the following things are important:

Prelims level: World Magnetic Model

Mains level: Magnetic Pole Drifting


News

  • Rapid shifts in the Earth’s north magnetic pole are forcing researchers to make an early update to a model that helps navigation by ships, planes and submarines in the Arctic.

Shifting Magnetic North Pole

  1. Magnetic North Pole wanders, and every few hundred thousand years, the polarity flips so that a compass would point south instead of north.
  2. Liquid churning in Earth’s core generates most of the magnetic field, which varies over time as the deep flows change.
  3. However, the magnetic field has been changing so quickly and erratically that while conducting a routine check in early 2018, British and US researchers realized drastic steps were needed.
  4. The shift they observed was so large it was on the verge of exceeding the acceptable limit for navigation errors.
  5. Scientists must periodically update the World Magnetic Model to map this process, and the most recent version – produced in 2015 – was intended to last until 2020.

Tracking the movement

  1. The wandering pole is driven by unpredictable changes in liquid iron deep inside the Earth.
  2. It’s moving at about 50 km (30 miles) a year.
  3. It didn’t move much between 1900 and 1980 but it’s really accelerated in the past 40 years.
  4. On the contrary, the South magnetic pole drift is very slow (less than 10 km per year).
  5. It has not changed much over the past few decades, and hence provided a much smaller contribution to the overall model declination error.

Why Drift?

  1. The Earth’s magnetic field is in a permanent state of change.
  2. Magnetic north drifts around and every few hundred thousand years the polarity flips so a compass would point south instead of north.
  3. The strength of the magnetic field also constantly changes and currently it is showing signs of significant weakening.

Effect on Life

  1. Life has existed on the Earth for billions of years, during which there have been many reversals.
  2. There is no obvious correlation between animal extinctions and those reversals. Likewise, reversal patterns do not have any correlation with human development and evolution.
  3. It appears that some animals, such as whales and some birds use Earth’s magnetic field for migration and direction finding.
  4. Since geomagnetic reversal takes a number of thousands of years, they could well adapt to the changing magnetic environment or develop different methods of navigation.

Effect on Climate

  1. Earth’s magnetic field, which has existed for at least 3.45 billion years, provides a shield from the direct impact of solar radiation.
  2. Even with Earth’s strong magnetic field today, we’re still susceptible to solar storms that can damage our electricity-based society.
  3. The fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.

Back2Basics

World Magnetic Model

  1. The World Magnetic Model (WMM) is a large spatial-scale representation of the Earth’s magnetic field.
  2. It consists of a degree and order 12 spherical harmonic expansion of the magnetic potential of the geomagnetic main field generated in the Earth’s core.
  3. The charts are used to convert between compass measurements of magnetic north and true north.
  4. It can be found in the navigation systems of ships and airplanes as well as geological applications (such as drilling and mining).
  5. Researchers from the U.S.’s National Oceanic and Atmospheric Administration (NOAA) maintain the WMM.
  6. The charts, known as the World Magnetic Model (WMM), are used to convert between compass measurements of magnetic north and true north
  7. The WMM is also part of map applications in smartphones, including the Google Maps App.

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Volcano erupts in Indonesia

Note4students

Mains Paper 1: Geography | Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc

From the UPSC perspective, the following things are important:

Prelims level: Mount Soputan

Mains level: Volcanic eruptions and Plate Tectonics Theory


News

Mount Soputan erupts

  1. A volcano, Mount Soputan has erupted in Indonesia’s North Sulawesi province spewing a column of ash measuring 7.5 km to the sky.
  2. Soputan is a small stratovolcano that rises to an elevation of 1,784m (5,853 ft).
  3. The cone is made of andesite and basalt rock.
  4. The volcano is one of Sulawesi’s most active, with 39 confirmed eruptions in the last 600 years.
  5. It is one of 129 active volcanoes in Indonesia which lies on a vulnerable quake-hit zone called “the Pacific Ring of Fire”.

Pacific Ring of Fire

  1. The Ring of Fire is a major area in the basin of the Pacific Ocean where many earthquakes and volcanic eruptions occur.
  2. In a large 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and plate movements.
  3. It has 452 volcanoes (more than 75% of the world’s active and dormant volcanoes).
  4. About 90% of the world’s earthquakes and 81% of the world’s largest earthquakes occur along the Ring of Fire.
  5. The Ring of Fire is a direct result of plate tectonics: the movement and collisions of lithospheric plates, especially subduction in the northern portion.

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[op-ed snap] Cool it: on labour loss due to heatwave

Note4students

Mains Paper 1: Geography | changes in critical geographical features (including waterbodies & ice-caps) & in flora & fauna & the effects of such changes

From the UPSC perspective, the following things are important:

Prelims level: UNFCCC, Heatwaves

Mains level: Impact of climate change on various weather events


Context

Loss of crucial labour hours due to heat waves

  1. The staggering loss of an estimated 153 billion hours of labour during 2017 due to rising temperatures around the globe is a reminder to governments that they are not doing enough to dramatically curb greenhouse gas emissions
  2. The Lancet countdown on health and climate has reported that India was particularly affected by the rising frequency of heatwave events and lost about 75 billion hours of work, a significant part of it in the agricultural sector

Impact on India

  1. This has worrying implications for rural employment and the well-being of a large section of the population that depends on farming
  2. At stake for all countries in the developing world is the health of millions, many of them already vulnerable to extreme weather events
  3. From a public health perspective, the report sounds a warning that rising temperatures will enable the dengue virus and malaria to spread farther and faster
  4. This is also true of some other infections

Measures that need to be taken by India

  1. It is vital that India gets more ambitious about cutting back on carbon emissions, even as it presses for the fulfilment of the climate finance obligations of developed countries under the Paris Agreement of the UN Framework Convention on Climate Change
  2. A further reduction in the share of coal in the energy mix through sustained support for renewable energy, particularly solar photovoltaics, must form the cornerstone of national policy
  3. This must be matched by a shift away from the use of fossil fuels for transport, and the induction of more electric vehicles
  4. Such a policy would yield the parallel benefit of improving air quality
  5. Ambient air pollution led to the premature death of an estimated half a million people in India in 2015

Garnering international consensus for changing climate fund usage

  1. The consensus on climate change is that it has begun to affect the intensity and frequency of extreme weather events
  2. India’s approach to adaptation should, therefore, prepare for catastrophes with a well-considered plan to provide relief and rehabilitation
  3. If the Centre and State governments can arrive at a consensus on the strong climate link to the excessive rain in Kerala and Cyclone Gaja in Tamil Nadu, for instance, a case could be made for climate funds under the Paris Agreement
  4. Such a claim has to be supported by a perspective plan that identifies vulnerable regions and communities and incorporates transparent systems for funds utilisation

Way forward

  1. The aggravated impact of climate change on health is a serious issue for policymakers to consider
  2. The importance of funds for adaptation is underscored by Lancet’s finding that 99% of losses from climate-related events in low-income countries were not insured
  3. Increased exposure to heatwaves needs a policy response, nationally and globally

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Indian monsoons influence Atlantic hurricanes: study

An Indian monsoon steers tropical cyclones across the Atlantic

Note4students

Mains Paper 1: Geography | Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

From UPSC perspective, the following things are important:

Prelims level: Indian, Atlantic Ocean (Features & location), Indian monsoon, El Nino, La Nina, Hurricanes

Mains level: Indian monsoon impact on various other geographical features


Indian monsoon impact

  1. Strong monsoons in the Indian Ocean can induce easterly winds that push Atlantic Ocean hurricanes westward, increasing the likelihood they will make landfall in the Americas
  2. The newly-discovered relationship could help scientists better predict the path of oncoming hurricanes, especially in late summer months like September, when Atlantic hurricane activity peaks
  3. As the climate continues to warm, the monsoon could have an increasing influence on the paths of Atlantic hurricanes

How the phenomenon works

  1. In years where summer rainstorms in India are stronger, Atlantic hurricanes move further westward towards land
  2. In years where the rains are not as strong, hurricanes tend to curve northward earlier and fizzle out in the North Atlantic Ocean
  3. Strong monsoons influence hurricane steering by enhancing the effects of the North Atlantic subtropical high, a centre of high atmospheric pressure in the Atlantic Ocean
  4. When the subtropical high increases, stronger winds come from the east and push hurricanes westward

Effect of El Nino & La Nina

  1. Previous research has attributed changes in hurricane steering to El Nino-Southern Oscillation (ENSO), a periodic fluctuation in sea surface temperature and air pressure in the equatorial Pacific Ocean
  2. Scientists have traditionally relied on the La Nina cool phase of ENSO to make predictions about how strong a particular Atlantic hurricane season will be, but have trouble forecasting the paths of individual hurricanes
  3. La Nina and the Indian monsoon are correlated, but the strength of the monsoon influences the steering of hurricanes independently of La Nina fluctuations, which are responsible for changes in hurricane frequency
  4. La Nina fluctuations may result in more Atlantic hurricanes, but strong Indian monsoons steer them further westward, making it more likely they will make landfall in the Americas

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Newest phase in Earth’s history named after Meghalaya rock

Image result for A layer (marked in pic) in this stalagmite from Meghalaya he

Note4students

Mains Paper 1: Geography | Salient features of world’s physical geography

From UPSC perspective, the following things are important:

Prelims level: Meghalayan age, Holocene Epoch, International Union of Geological Sciences (IUGS), International Commission on Stratigraphy

Mains level: Geological era’s of Earth and their important features


Meghalayan Age

  1. Scientists have created a new phase in Earth’s geological history and named it Meghalayan, after a stalagmite from a cave in the Indian state of Meghalaya
  2. The stalagmite helped define climatic events 4,200 years ago, marking the beginning of the phase that continues till today

The beginning of a new age

  1. The Meghalayan Age began with a mega global drought that devastated ancient agricultural civilisations from Egypt to China
  2. It is part of a longer period known as the Holocene Epoch, which reflects everything that has happened over the past 11,700 years

Uniqueness of this age

  1. The Meghalayan is unique because it is the first interval in Earth’s geological history that coincided with a major cultural event, as agricultural societies struggled to recover from the shift in climate
  2. The droughts over a 200-year period resulted in human migrations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus valley and the Yangtze river valley
  3. The change in global climate was likely triggered by shifts in ocean and atmospheric circulation

IUGS findings

  1. This discovery was done by the International Commission on Stratigraphy of the International Union of Geological Sciences (IUGS)
  2. The commission then forwarded these proposals to its parent body, the IUGS, for consideration, and the executive committee of IUGS voted unanimously to ratify them
  3. Two other ages — the Middle Holocene Northgrippian Age and the Early Holocene Greenlandian Age — with beginnings defined at climatic events that happened about 8,300 years and 11,700 years ago, respectively, were also approved by the International Commission on Stratigraphy, which is responsible for standardising the geologic time scale

Distinct periods of Earth’s geology

  1. Geologists divide the 4.6-billion-year existence of Earth into distinct periods
  2. Each period corresponds to significant events such as the break-up of continents, shifts in climate, and the emergence of particular types of animals and plant life
  3. These units of the geologic time scale are based on sedimentary strata that have accumulated over time and contain within them sediment types, fossils and chemical isotopes that record the passage of time as well as the physical and biological events that produced them

Back2Basics

International Union of Geological Sciences (IUGS)

  1. The IUGS is an international non-governmental organization devoted to international cooperation in the field of geology
  2. It is a Scientific Union member of the International Council for Science (ICSU), which it recognizes as the coordinating body for the international organization of science
  3. Currently, geologists from 121 countries (and regions) are represented in IUGS through a 121 Adhering Organization
  4. IUGS promotes and encourages the study of geological problems, especially those of worldwide significance, and supports and facilitates international and interdisciplinary cooperation in the earth sciences
  5. The Union’s Secretariat is currently located at the Chinese Academy of Geological Sciences in Beijing, China
  6. The Union is the main scientific sponsor of the International Geological Congress (IGC), which takes place every four years
  7. IUGS is a joint partner with UNESCO for the International Geoscience Programme (IGCP) and they also participate in the Global Network of National Geoparks (GGN)
  8. The Geological Society of London oversees the production and distribution of IUGS Publications
  9. As of 2016 IUGS runs Seven international commissions covering the following topics:
  • Commission for the Management and Application of Geoscience Information (CGI)
  • Geoscience Education, Training and Technology Transfer (COGE)
  • Geoscience for Environmental Management(GEM)
  • International Commission on Stratigraphy (ICS)
  • International Commission on the History of Geological Sciences (INHIGEO)
  • Commission on Tectonics and Structural Geology (TECTASK)
  • Commission on Global Geochemical Baselines

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Strong winds in Atlantic create high waves off Indian coasts over 10,000 km away

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Note4students

Mains Paper 1: Geography | Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

From UPSC perspective, the following things are important:

Prelims level: INCOIS, Swell waves, IMD colour codes

Mains level: India’s vulnerability to sea level changes and measures that can be taken to avoid major casualties


High energy waves hit Indian coasts

  1. Strong winds in the Atlantic Ocean, more than 10,000 kms from the Indian coasts, have given rise to high energy waves in the Arabian Sea and the Bay of Bengal
  2. These high period waves can travel long distances and become more strong as they reach the coast

Waves Forecast

  1. The Indian National Centre for Ocean Information Services (INCOIS), a unit of the Ministry of Earth Sciences, issued ‘swells’ alerts to states
  2. After the devastating tsunami of 2004, India developed the necessary infrastructure to issue alerts in case of any abnormal wave activity in the seas

Colour codes for the forecast

  1. The IMD has four colour codes to denote the levels of caution
  2. The Red alert is considered serious and demands action by government agencies
  3. The Orange denotes an alert to be prepared for any extreme weather event
  4. The Yellow indicates that the authorities must keep a watch on the natural calamity
  5. The Green denotes that no action should be taken and that situation is normal

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Indian National Centre for Ocean Information Services (INCOIS)

  1. INCOIS is an autonomous organization of the Government of India, under the Ministry of Earth Sciences
  2. ESSO-INCOIS is a unit of the Earth System Science Organization (ESSO)
  3. ESSO- INCOIS is mandated to provide the best possible ocean information and advisory services to society, industry, government agencies and the scientific community through sustained ocean observations and constant improvements through systematic and focused research

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Swell waves forecast along India’s coasts

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Note4students

Mains Paper 1: Geography | Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

From UPSC perspective, the following things are important:

Prelims level: Swell waves, NDMA, INCOIS

Mains level: Impact of sea level changes on India


High energy swell waves forecasted

  1. India’s coasts will be lashed by ‘high energy swell waves’ according to an alert from the National Disaster Management Agency (NDMA)
  2. This is based on a forecast from the Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS), which is charged with issuing tsunami alerts
  3. The low-lying coasts of Kerala and West Bengal are particularly vulnerable

Back2Basics

Swell Waves

  1. ‘Swell waves’ are massive ripples that form on the sea due to winds coming from as far away as Madagascar
  2. Swells are collections of waves produced by storm winds raging hundreds of miles out to sea, rather than the product of local winds along beaches
  3. They are often referred to as surface gravity waves
  4. Swell continues to move under winds and waves that have long since changed direction, it can even head in the opposite direction as the wind and waves
  5. They might appear to be tsunami-like waves but have completely different characteristics
  6. They can have heights between 2 m and 3 m and periods between 17-22 seconds

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Rare meteorite may hold clue to life’s origin

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Mains Paper 3: Science & Technology | Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology

From UPSC perspective, the following things are important:

Prelims level: Meteorites, Geological Survey of India (GSI)

Mains level: Studies related to the origin of life


Evidence of origins of life

  1. A study of two meteorites by the Geological Survey of India (GSI) has concluded that they may contain significant clues to the origins of life
  2. These meteorites fell in Assam and Rajasthan over a span of 13 hours in 2017

Material dates back to the pre-sun era

  1. The Mukundpura (Rajasthan) meteorite is a carbonaceous meteorite, one of the most primitive types
  2. They contain grains of calcium and iron which date to a time before the sun came into existence
  3. They may contain clues to the formation of early life

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Meteorites

  1. A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon
  2. When the object enters the atmosphere, various factors like friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy
  3. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star
  4. Meteorites have traditionally been divided into three broad categories: stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites that are largely composed of metallic iron-nickel; and, stony-iron meteorites that contain large amounts of both metallic and rocky material
  5. Meteorites mostly originate from the asteroid belt between Mars and Jupiter
  6. Meteorites are always named for the places they were found usually a nearby town or geographic feature
  7. In cases where many meteorites were found in one place, the name may be followed by a number or letter

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Global temperature in January 2018 fifth highest for the month since 1880: report

Note4students

Mains Paper 1: Geography | changes in critical geographical features (including waterbodies & ice-caps) & in flora & fauna & the effects of such changes.

From UPSC perspective, the following things are important:

Prelims level: Global warming, Arctic sea

Mains level: Effects of global warming


Fifth warmest month since 1880

  1. Global temperature in January 2018 was the fifth highest for the month since 1880
  2. Another analysis said that earth’s polar regions continue to experience record-low ice conditions
  3. Arctic sea ice extent the smallest for the month in 39 years

Continued warming 

  1. The latest analysis only adds to the long list of records that are being set by global warming in the last few years
  2. Last month, NASA had said that earth’s global surface temperature in 2017 ranked the second warmest since 1880

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Rare ‘super blood blue moon’ visible on Jan. 31

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Note4students

Mains Paper 3: Science & Technology | Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology

From UPSC perspective, the following things are important:

Prelims level: Super blood blue moon, Supermoon, Lunar eclipse

Mains level: Solar and Lunar eclipses and their effects on Earth


Astronomical trifecta to appear on January 31

  1. A rare “super blood blue moon” may be glimpsed January 31 in parts of western North America, Asia, the Middle East, Russia and Australia
  2. It combines three unusual lunar events — an extra big super moon, a blue moon and a total lunar eclipse

Blue moon

  1. A blue moon refers to the second full moon in a month
  2. Typically, a blue moon happens every two years and eight months

Supermoon

  1. Supermoons happen when the moon is closest to Earth in its orbit
  2. This point, called the perigee, makes the moon appear 14% larger and 30% brighter
  3. Supermoons can happen four to six times a year

Lunar eclipse

  1. A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra
  2. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle
  3. Lunar eclipses occur at least twice a year
  4. Lunar eclipses during a supermoon happen regularly

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Rain in western hemisphere linked to currents in Atlantic Ocean, says study

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Note4students

Mains Paper 1: Geography | Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

From UPSC perspective, the following things are important:

Prelims level: Atlantic Ocean

Mains level: Ocean currents, rainfall patterns


Study on climate factors affecting rains

  1. Changes in ocean currents in the Atlantic Ocean influence rainfall in the western hemisphere and the two systems have been linked for thousands of years
  2. The Atlantic Ocean surface circulation, and however that changes, has implications for how the rainfall changes on continents

Importance of Atlantic Ocean surface circulation

  1. The Atlantic Ocean surface circulation is an important part of the Earth’s global climate, moving warm water from the tropics towards the poles
  2. The Atlantic Ocean surface currents correlate with rainfall patterns in the western hemisphere

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Hurricane Matthew pummels Haiti and Cuba, evacuations ordered in U.S.

  1. Hurricane Matthew pummeled Haiti and moved on to Cuba
  2. Impact: Killed 7 people, unleashed floods and forced hundreds of thousands to flee
  3. It is the Caribbean’s worst storm in nearly a decade
  4. Civil protection officials in Haiti are struggling to communicate with the south after Matthew’s furious wind and rain blew down telephone lines
  5. The collapse of a bridge cut off the only road linking Port-au-Prince to the peninsula that makes up southern Haiti

Discuss: Tropical cyclones are largely confined to Bay of Bengal, South China Sea, Gulf of Mexico. Why? [Mains 2014, GS-I]

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Nearly 400 tourists trapped as Indonesian volcano erupts

  1. A volcano erupted at Mount Rinjani in Lombok, Indonesia
  2. Mount Barujari that forms part of Rinjani was seen emitting a 2,000-metre-high column of smokeRinjani, the second highest volcano in Indonesia stands 3,726 metres high
  3. It attracts thousands of tourists annually for a three-day trek to the mountain top, which has a lake in its boiler
    Indonesia sits on the Pacific Ring of Fire
  4. Ring of Fire: An area of high seismic and volcanic activity which is home to more than 400 volcanoes, including at least 129 that are still active and 65 qualified as dangerous

Discuss: Earthquakes and volcanism are some of the most important topics for Mains & Pre both. Go back to your NCERTs or GC Leong and revise them now!

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Major quake strikes off Sumatra

  1. Context: Warning was issued for West Sumatra, North Sumatra and Aceh after the quake of magnitude 7.9
  2. Epicentre: 808 km southwest of Padang and 10 km deep
  3. History: Indonesia, especially Aceh, was badly hit by the Indian Ocean tsunami in 2004
  4. Pacific Ring of Fire: A highly seismically active zone, where different plates on the earth’s crust meet and create a large number of earthquakes and volcanoes

sumatara_2759440f


  1. Context: Warning was issued for West Sumatra, North Sumatra and Aceh after the quake of magnitude 7.9
  2. Epicentre: 808 km southwest of Padang and 10 km deep
  3. History: Indonesia, especially Aceh, was badly hit by the Indian Ocean tsunami in 2004
  4. Pacific Ring of Fire: A highly seismically active zone, where different plates on the earth’s crust meet and create a large number of earthquakes and volcanoes

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