Climate Change Impact on India and World – International Reports, Key Observations, etc.

Oceans absorb 90% of human-induced planet warming: Study


From UPSC perspective, the following things are important :

Prelims level: Heat Budget of Earth

Mains level: Read the attached story


The study published in the journal Earth System Science Data estimates that almost 90% of the warming that has occurred in the last 50 years has been absorbed by the ocean, with the remaining heat absorbed by the land, cryosphere and atmosphere.

Earth’s energy balance: A quick recap


  • It is the balance between the amount of energy that Earth receives from the Sun and the amount of energy that Earth radiates back into space.
  • It is also known as the radiation budget.
  • The energy from the Sun that Earth receives is mainly in the form of visible light and ultraviolet radiation.
  • This energy is absorbed by the Earth’s surface and atmosphere, which then radiate it back into space in the form of infrared radiation.
  • The balance between incoming and outgoing radiation is crucial for maintaining the Earth’s temperature and climate.
  • Any imbalance between the two can lead to global warming and climate change.
Total incoming solar radiation Approximately 342 W/m² reaches Earth’s atmosphere
Albedo About 30% of incoming solar radiation is reflected back to space
Greenhouse effect Remaining 70% of incoming solar radiation is absorbed by Earth’s surface and atmosphere, creating the greenhouse effect
Atmospheric heat Atmosphere contains only 0.001% of Earth’s heat energy, but is crucial in regulating heat budget


Key highlights of the Study: Heat Accumulation


  • The study estimates that approximately 381 zettajoules (ZJ) of heat accumulated on the planet from 1971-2020 due to anthropogenic emissions.
  • This roughly equals a heating rate of approximately 0.48 watts per square metre (Earth Energy Imbalance or EEI). EEI is the difference between incoming and outgoing solar radiation.
  • According to the study, about 89% of the accumulated heat is stored in the ocean, 6% on land, a percent in the atmosphere, and about 4% available for melting the cryosphere.


(1) Land Heat Accumulation

  • Heat accumulated on land drives up ground surface temperatures, which may increase soil respiration, releasing carbon dioxide in the process.
  • Higher soil respiration will likely decrease soil water, depending on climatic and meteorological conditions and factors.

(2) Inland Water Bodies and Permafrost Thawing

  • Heat storage within inland water bodies has increased to roughly 0.2 ZJ since 1960. For permafrost thawing, it was about 2 ZJ.
  • The accumulation of heat in inland water increases lake water temperatures, making conditions ripe for algal blooms.
  • Permafrost heat content could inject methane and carbon dioxide into the atmosphere, the researchers warned.

(3) Ocean and Troposphere heating

  • The upper ocean (0-300 and 0-700 meters depth) has taken up a major fraction of heat, according to the new estimates.
  • During 2006-2020, ocean warming rates for the 0-2,000 meters depth reached record rates of roughly 1.03 watts per square meter.
  • The troposphere is also warming up due to increased heat accumulation.

(4) Cryosphere heating

  • The cryosphere – the frozen water part of the Earth system – gained roughly 14 ZJ of heat from 1971-2020.
  • Half of the uptake triggered the melting of grounded ice, while the remaining half is linked to the melting of floating ice.
  • The Antarctic Ice Sheet contributed about 33% to the total cryosphere heat gain, while Arctic sea ice stood second, having contributed 26%.


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