Oceans have absorbed more heat than previously thought, study finds

Dogtooth tuna

Courtesy of The Smithsonian Channel

This, the paper's authors write, "suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases and the thermal component of sea-level rise".

Because the ocean takes up around 90% of all excess energy as the planet warms, knowing the actual amount of energy makes it possible to estimate the surface warming we can expect in the future.

"We thought that we got away with not a lot of warming in both the ocean and the atmosphere for the amount of Carbon dioxide that we emitted", Laure Resplandy, a Princeton geoscientist who led the study told the Washington Post. "Our data show that it would have warmed by 6.5 degrees Celsius [11.7 degrees Fahrenheit] every decade since 1991".

The Sea of Japan, for example, has warmed around 3 degrees Fahrenheit in the past 100 years, as Reuters recently reported.

During this time frame, the researchers calculated that the world's oceans took up more than 13 zettajoules - which is a joule, the standard unit of energy, followed by 21 zeroes.

"The result significantly increases the confidence we can place in estimates of ocean warming and therefore helps reduce uncertainty", said Ralph Keeling, a geophysicist at the University of California-San Diego and co-author of the study. (3.6?), it is all but certain that society will face widespread and unsafe consequences of climate change.

The UK has experienced more weather extremes over the past 10 years compared to previous decades, according to a Met Office report published on Friday.

The study results are the first to come from a measuring technique independent from the dominant method behind existing research. This allows them to accurately measure ocean temperatures globally, dating back to 1991, when accurate data from a global network of stations became available. They measured ocean heat by looking at the combined amount of O2 and Carbon dioxide in air, a quantity they call "atmospheric potential oxygen" or APO.

"We thought that we got away with not a lot of warming in both the ocean and the atmosphere for the amount of Carbon dioxide that we emitted", she is quoted as saying.

Both gases are soluble in water, but the rate at which water absorbs them decreases as it warms.

"When the ocean warms, the amount of these gases that the ocean is able to hold goes down", said Dr Resplandy. APO also is influenced by burning fossil fuels and by an ocean process involving the uptake of excess fossil-fuel CO2.

It found that for each of the last 25 years, oceans had absorbed heat energy equivalent to 150 times the amount of electricity mankind produces annually.

The UN report used the old assumptions for heat absorbed in the ocean, Miller added. The work was funded by the Climate Program Office of the National Oceanic and Atmospheric Administration (grant NA13OAR4310219) and the Princeton Environmental Institute.

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