A study published today in the journal Nature reported that our oceans have been taking more than their fair share of heat – literally. For the past twenty-five years, the oceans have been absorbing 150 times the amount of energy in heat that humans produce annually. That’s a lot of heat energy – over 13 zettajoules between 1991 and 2016 in fact! (Watch the video below to learn what a joule is – then add 21 zeroes to that to get a zettajoule!)
The investigation was carried out by researchers at Princeton and the Scripps Institution of Oceanography at the University of California-San Diego and suggests that previous estimates regarding the oceans’ sensitivity to fossil fuel emissions were drastically underestimated. In fact, author of the study, Laure Resplandy, said that her and her co-authors' estimate is more than 60 percent higher than the figure in the 2014 Fifth Assessment Report on climate change from the United Nations Intergovernmental Panel on Climate Change (a.k.a the 2014 version of the IPCC report that just went viral around the world several weeks ago).
The researchers employed a unique measuring technique in order to secure their data. According to Princeton, they utilized the Scripps Institute’s high-precision measurements of oxygen and carbon dioxide in the air to quantify how much heat the oceans have stored from 1991 to 2016. “They measured ocean heat by looking at the combined amount of O2 and CO2 in the air, a quantity they call "atmospheric potential oxygen" or APO. The method depends on the fact that oxygen and carbon dioxide are both less soluble in warmer water,” reported Science Daily. “As the ocean warms, these gases tend to be released into the air, which increases APO levels. APO also is influenced by burning fossil fuels and by an ocean process involving the uptake of excess fossil-fuel CO2. By comparing the changes in APO the scientists observed with the changes expected due to fossil-fuel use and carbon dioxide uptake, they were able to calculate how much APO emanated from the ocean becoming warmer. That amount coincides the heat-energy content of the ocean.”
Scientists are already aware of the fact that Earth’s oceans absorb approximately 90% of all the planet’s excess energy; however, this new quantification of the amount of energy will allow for better projections of surface sea temperatures in our warming climate so that we can promote more adequate policies and mitigation strategies.
"The result significantly increases the confidence we can place in estimates of ocean warming and therefore helps reduce uncertainty in the climate sensitivity, particularly closing off the possibility of very low climate sensitivity," co-author Ralph Keeling said. From this new quantification, the authors say that in order to keep climate change at a bay, humans must now reduce greenhouse gas emissions 25% more than what models previously dictated.