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GS Paper: GS1-15.Geographical features and their location- Changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

  • [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.

     

  • Solar Storms

     

    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.

  • Yongle Blue Hole (YBH)

     

    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.

  • Why do we have Leap Years?

     

    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.

  • Specie in news: ‘World’s largest’ subterranean fish

     

    Systematic exploration of the Meghalayan caves has been underway for almost 30 years and hundreds of kilometres of cave passages have been explored and mapped. In a cave in a remote forested area of Meghalaya’s Jaintia Hills a research expedition found large specie of a subterranean fish (occurring under the earth’s surface).

    About the fish

    • The blind fish was over 40 cm. It has not been named so far.
    • It is nearly five times the mean length (85mm/8.5 cm) for all known subterranean fish to date.
    • The only other species exceeding 300mm (30 cm) in length are eel-like Synbranchidae with nothing like the bulk of the new fish.
    • The 250-known subterranean (occurring under the earth’s surface) fish species around the world measure only around 8.5 cm on average.
    • The specialists say that possibly one (or more) populations of these fish became isolated deeper in the caves and over generations became adapted to the dark, losing their eyes in the process.

    Closest resemblance

    • The experts feel that the fish species is very similar to the Golden Mahseer or the Tor Putitora, one of the most famous game fish of the Himalayan rivers.
    • Unique characters that distinguishes it from the Golden Mahseer is the lack of pigmentation, a lack of eyes and of course, its subterranean habitat – being locked in caves.
    • There are ‘normal’ Golden Mahseer in the area too but there is not much surface water (at least in the dry winter months) so fish end up in the cave pools and underground rivers.

    Features of Subterranean ecosystems

    • Subterranean ecosystems are considered extreme, high-stress environments characterised by darkness, truncated food webs and food scarcity.
    • Despite this, they harbour exceptional vertebrate and invertebrate taxa (21,000+ species), many of which are evolutionarily unique, and relics of ancient fauna given their long-term isolation.
    • Many cave fish show different adaptations – some don’t have eyes, some have reduced eyes, some don’t have fins, some have weird body shapes.

  • Species in news: Thanatotheristes

     

    Scientists have found that a dinosaur fossil, found in Alberta in Canada in 2010, belongs to a new species of tyrannosaur. They have named it Thanatotheristes, which means “reaper of death”.

    Thanatotheristes

    • Tyrannosaurs were one of the largest meat-eating dinosaurs to have ever lived, with very large and high skulls, and the best known among them is the Tyrannosaurus rex, celebrated in the Jurassic Park series.
    • The 79-million-year-old fossil that the researchers have found is the oldest tyrannosaur known from northern North America.
    • Thanatotheristes preyed on large plant-eating dinosaurs such as the horned xenoceratops and the dome-headed colepiochephale.
    • The research suggests that tyrannosaurs did not have one general body type; rather different tyrannosaur species evolved distinct body sizes, skull forms and other such physical features.
    • The fossil specimen is important to understand the Late Cretaceous period, which is the period when tyrannosaurs roamed the Earth.

  • Explained: What new monsoon dates mean

     

    The India Meteorological Department (IMD) had decided to revise the normal onset and withdrawal dates for the monsoon in some parts of the country from this year.

    Onset of Monsoon

    • The four-month southwest monsoon season, which brings as much as 70 per cent of the country’s annual rainfall, officially begins on June 1, with the onset over Kerala, and ends on September 30.
    • It takes about a month and half after onset on the Kerala coast to cover the entire country; and about a month, beginning from the northwestern parts of the country on Sept. 1 to withdraw completely.
    • Although the June 1 date for the onset of the monsoon on the Kerala coast is unlikely to be changed, the dates for onset in many other parts of the country are expected to be revised.
    • Mumbai, for example, expects to start getting rain from June 10 the revision is likely to push this date back by a few days.
    • Effectively, the monsoon is now expected to have later arrival and withdrawal dates in most parts of the country.

    Why was this revision needed?

    • The main reason for the revision in the normal dates is the changes in precipitation patterns that have been taking place over the last many years.
    • In the last 13 years, for example, only once has the onset over the Kerala coast happened on June 1.
    • While two or three days of earlier or later onset falls within the yearly variability in several years the onset happened five to seven days late.
    • Similarly, the commencement of withdrawal has happened in the first week of September only twice during this period, and last year, the withdrawal started as late as October 9 — and was completed in around just a week.

    Recent peculiarity with the exam

    • One of the significant changes being noticed is that rainfall is getting increasingly concentrated within a narrow band of days within the monsoon season.
    • So, there are extremely wet days followed by prolonged periods of dry days.
    • IMD data show that over several previous years, nearly 95 per cent of monsoon precipitation in 22 major cities of the country had happened over a period of just three to 27 days.
    • Delhi, for example, had received almost 95 per cent of its monsoon rainfall over just 99 hours. And half of Mumbai’s monsoon rain had fallen over just 134 hours, or five and a half days, on average.

    Regional variations

    • Patterns of regional variations in rainfall are also changing
    • Areas that have traditionally received plenty of rainfall are often remaining dry, while places that are not expected to get a lot of monsoon rain have sometimes been getting flooded.
    • Climate change could be one of the factors driving these changes, but there could be other reasons as well.

    What will be the impact of IMD’s move?

    For Farmers

    • The revisions are meant to reflect the changes in precipitation patterns in recent years.
    • New dates will likely nudge farmers in some parts of the country to make slight adjustments in the time of sowing their crops.
    • It would definitely have an impact on our agriculture practices — when to start sowing, when to harvest.
    • So, even if there is a delay in the arrival of monsoon by three to four days over a region, it would not matter much if there is a fairly good rainfall distribution thereafter.
    • The change in dates would affect water management practices as well.

    For Industries

    • The planning that goes to beat the heat — several cities execute heat action plans — just ahead of the monsoon would have to factor in the need to be prepared for longer periods of heat.
    • Rajeevan said many other activities including industrial operations, the power sector, or those using cooling systems, would also need to change their behaviour.
    • The power grid can, for example, have more realistic planning for peak periods of electricity consumption in certain months.

    Way Forward

    • The changed dates are expected to be announced in April, when the IMD makes its first forecast for the monsoon.
    • Agro-meteorologists, however, agree that more than the onset, it is the information about the spatio-temporal distribution of rainfall that will be more helpful for farmers.
    • Ultimately, the change in normal dates of the onset and withdrawal of the monsoon would help people understand when to expect rains, and to plan their activities accordingly.

  • Eruption of Taal Volcano

     

    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.

  • Global Geological And Climatic Events

  • Monsoon Updates

    How does El Nino affect Indian Monsoon? A Comprehensive Explainer

    As many reports speculated that El Nino is the main cause of the worsening Indian Monsoon and has played badly with Indian agriculture, we thought that we should take a big picture of El Nino and it’s scope in India.

     

    • The Monsoon is basically a result of the flow of moisture laden winds because of the variation of temperature across the Indian Ocean.
    • There are a number of climatic phenomena which affect it namely the El nino, La nina etc.
    • We will look at their origin, impact and way forward.

    Now, let’s take a overview and develop our understanding. 

    What happens in a Normal Year?

    • Peru Current = Humboldt Current = Cold Current.
    • During normal year 2 things are very strong – Cold Peru Current and Trade Winds.
    • As a result, cold water is dragged from Peru towards Australia.

    What would be the result of this exchange?

    • Warm water region around Australia is called Western Pacific Pool (WPP).
    • WPP = low pressure = warm air ascends = cloud formation = rain over North Australia
    • This air also joins walker cell and begins descending near Peru.
    • Descending air = anti-cyclonic condition = high pressure = stability = no cloud/rain = Drought in Atacama Desert.

    (Simply, Walker cell is the result of a difference in surface pressure and temperature over the western and eastern tropical Pacific Ocean)

    What happens below the water from Peru to Australia ?

    At Peru coast, cold water upwelling brings nutrient to surface + more lunch for Plankton + more fishes = Peru fishermen gets happy.

    What happens above the water from Australia towards Peru?

    Warm water + low atmospheric pressure = good rainfall over Australia & Indonesia.

    What happens in La Nina Year?

    Same things as in a “normal” year, but 2 things become even “stronger” –

    • Cold Peru Current
    • Trade Winds

    What’s the Result?

    • Too many fishes at Peru coast = oversupply of fishes = prices become dirt cheap.
    • Too much rain / flood over Australia and Indonesia.

    This is what happens in normal and La Nino year, Let’s back to El Nino!

     

     

    What happens in an El Nino year?

    Two things become weak.

    • Cold Peru Current
    • Trade Winds
    • As result, cold water is not dragged from Peru to Australia.
    • But reverse happens, warm water is dragged from Australia towards Peru.
    • Consequently, warm water + low pressure condition develops in the Eastern Pacific (Peru) and Cold condition + high pressure in Western Pacific (Australia).

    What will happen if pressure is inversely related with amount of rainfall ?

    • Rain & Floods at Peru, Atacama and even Southern USA
    • Drought at Northern Australia, Indonesia- even bushfires.
    • Storms and Hurricanes in East Pacific.
    • Coral bleaching (high temperature coral dies)

    But, what is the El Nino?

    • El Nino is an Oceanic and Atmospheric phenomenon that leads to unusual warming of water in the Peru coast, occurs every 3-5 years.
    • Consequently, warm water + low pressure condition develops in the Eastern Pacific (Peru) and Cold condition + high pressure in Western Pacific (Australia).
    • Since Pressure is inversely related with amount of rainfall, El Nino causes drought situation in Australia and South East Asia.
    • It weakens the trade winds and changes in Southern Oscillation, thereby affects the rainfall pattern across the world.

    el-nino-phenomenon

    What is Southern Oscillation?

    • Alternating of (tropical) sea level pressure between the eastern and western hemispheres.
    • We can measure Southern Oscillation by observing the pressure difference between Tahiti (French Polynesia) and Darwin (Australia).

    How does El Nino affect Indian Monsoon?

    • El Nino-Southern Oscillation (ENSO) water circulation happens between Australia and Peru.
    • But, the wind movement is part of larger atmospheric circulation hence affects the rainfall over India. But, how?
    • We have learned that During normal year, the warm water moves towards Australia, this pool of warm water is called Western Pacific Pool (WPP).

    So, from WPP air rises above and moves towards two walker cells –

    • Towards Peru coast = this affects rainfall in South America.
    • Towards Mascarene High Pressure zone near East Africa. So, this affect Indian monsoon.

    Why should India worry about?

    • Drought condition decreases the agriculture output, leads to food inflation.
    • Declined supply of cotton, oilseeds and sugarcane negatively affects the textile, edible oil and food processing industries respectively.

    What is the way forward?

    Let’s discuss first Near-term Solutions?

    • Government must expand farm insurance cover and advice financial institutions to settle crop insurance claims in the drought-hit areas without delay. Otherwise, it results in farmer suicides (e.g. Maharashtra farmers’ suicide ).
    • High quality seeds of alternative crops must be distributed among farmers in drought-affected areas.
    • Need of realistic assessment of ground level situation in order to estimate the shortfall of oilseeds and pulses and help traders with market intelligence.
    • Scrapping the APMC Act and allowing free flow of agricultural goods among the states.
    • This would help bridge the mismatch of demand and supply of goods, which is the underlying factor contributing inflation.

    What should be the Long-term Solutions?

    • Developing drought free crop varieties and distributing its subsidized seeds to the farmers. It is a part of National Action plan on climate change in Agriculture.
    • Using low water use technologies like drip and sprinkler irrigation.
    • The MSP regime in India has to provide more remuneration for less water consuming crops.
    • Strengthening community watershed management and development by protecting and conserving local water sources like ponds, lakes etc.
    • Developing early warning systems and alerting the farmers much in advance like recently launched Kisan SMS scheme.

    Do you find more solutions or any way out? then, Let us know!

     

    Published with inputs from Arun