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Rise in Ocean heat content

Rise in Ocean heat content

Why in news ?

As much as 93% of the extra heat that is released into the atmosphere due to human activity is absorbed by oceans. This has made oceans warm up at a rate that is about 40% faster than was told in the Inter-Governmental Panel on Climate Change (IPCC)’s Fifth Assessment Report (AR5). This study about  Rise in Ocean heat content  published in the journal, Science.

What is Ocean heat content :

  • The ocean is the largest solar energy collector on Earth. Not only does water cover more than 70 percent of our planet’s surface, it can also absorb large amounts of heat without a large increase in temperature.
  • This tremendous ability to store and release heat over long periods of time gives the ocean a central role in stabilizing Earth’s climate system.
  • Moreover,increasing concentrations of greenhouse gases are preventing heat radiated from Earth’s surface from escaping into space . 
  • Meanwhile, most of the excess heat is being stored in the upper ocean. As a result, upper ocean heat content has increased significantly over the past two decades.

Highlights of Rise in Ocean heat content

  • More than 90 percent of the warming that has happened on Earth over the past 50 years has occurred in the ocean.
  • Averaged over Earth’s surface, the 1993–2017 heat-gain rates are 0.36–0.40 watts per square meter for 0–700 meters, and 0.19–0.35 for depths of 700–2,000 meters.
  • Heat already stored in the ocean will eventually be released, committing Earth to additional warming in the future.
  • Increasing ocean heat content is contributing to sea level rise.

Global Impact  of  Rise in Ocean heat content

  • Heat absorbed by the ocean is moved from one place to another, but it doesn’t disappear. The heat energy eventually re-enters the rest of the Earth system by melting ice shelves, evaporating water, or directly reheating the atmosphere. Thus, heat energy in the ocean can warm the planet for decades after it was absorbed.
  • The warming oceans are also causing the glaciers from Greenland and Antarctica to melt. It is reported that the Greenland ice sheet melting is extraordinary compared with the history of the past 350 years.
  • Making the storms more vigorous and extreme is an outcome of the warming oceans. Examples are hurricane Harvey and typhoon Mangkhoot. The devastations caused by Harvey by the extraordinary deluge was the cause of warming of the Gulf of Mexico above the average level.
  • Ocean warming has led to increased rainfall in mid-latitudes and monsoon areas, and less rain in various sub-tropical regions. These changes will have impacts on crop yields in important food-producing regions such as North America and India.
  • The protection against climate change offered to us by oceans and their ecosystems – such as absorbing large amounts of CO2 and sheltering us from storms and erosion – is also likely to reduce as the ocean warms
  • The effect of this warming can be seen affecting marine biodiversity. The back-to-back coral bleaching events is the direct outcome of the warming of oceans.
  • The ocean warming is causing increased disease in plant and animal populations, and impacting human health as pathogens spread more easily in warmer waters, including cholera-bearing bacteria and harmful algal blooms that cause neurological diseases like ciguatera.
  • If ocean temperatures rise it will have an effect right beneath the ocean floor and it will allow the addition of another greenhouse gas, methane gas. Methane gas has been found under methane hydrate, frozen methane and water, beneath the ocean floor. With the ocean warming, this methane hydrate will begin to melt and release methane gas, contributing to global warming

Way Ahead

Expanding marine protected areas, introducing legal protection for the high seas, better evaluating the social and economic risks associated with warming oceans and continuing to fill gaps in scientific knowledge, as well as cutting greenhouse gas emissions rapidly and substantially this situation can be mitigated.

Background:

Coral bleaching is the phenomenon where the corals start expelling algae that live inside their tissues causing the corals turning completely white. Algae is the primary source (almost 90%) of energy of the corals. When bleaching happens, the corals begin to starve.

http://iasipstnpsc.in/economy/

https://www.climate.gov/news-features/understanding-climate/climate-change-ocean-heat-content

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