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 of the oceans' rise in temperature, more gas is being lost from the ocean into the atmosphere.
The UN report found that the planet will reach the crucial threshold of 1.5 degrees Celsius above pre-industrial levels by as early as 2030, precipitating the risk of extreme drought, wildfires, floods and food shortages for hundreds of millions of people.
First author Laure Resplandy, an assistant professor of geosciences and the Princeton Environmental Institute, 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 (IPCC).
"If you look at the IPCC 1.5C, there are big challenges ahead to keep those targets, and our study suggests it's even harder because we close the window for those lower pathways".
The oceans soaking up excess heat would only bring calamity to the world.
The study's findings suggest that if society is to prevent temperatures from rising above that mark, emissions of carbon dioxide must be reduced by 25 percent compared to what was previously estimated. Specifically, that means it will be more challenging to avoid flooding from sea level rise in coastal cities, violent hurricanes, and the death of almost all of Earth's coral reefs.
Researchers used Scripps' high-precision measurements of oxygen and Carbon dioxide in the air to determine how much heat the oceans have stored during the time span they studied.
The discovery took place because the authors of the new study were not satisfied with the information about the temperature and salinity of the ocean, which is compiled from a system of nearly 4,000 ocean buoys in waters around the world, called Argo. They gauged ocean heat by taking a gander at the consolidated measure of O2 and Carbon dioxide in air, an amount they call "atmospheric potential oxygen" or APO.
The report, however, relies on a novel approach that could revolutionize how scientists measure the ocean's temperature. For instance, warmer waters raise sea levels by melting ice, and the extra energy they hold cause more intense and frequent storms.
"Imagine if the ocean was only 30 feet deep", said Resplandy, who was a postdoctoral researcher at Scripps.
"So what we measured was the amount lost by the oceans, and then we can calculate how much warming we need to explain that change in gases".
Moreover, he warned that the heat the oceans have been absorbing can still be transferred back to the atmosphere in the centuries to come.
Others say that further work is required.
"The uncertainty in the ocean heat content change estimate is still large, even when using this new independent method, which also has uncertainties", said Thomas Froelicher from the University of Bern, Switzerland.
Climate sensitivity is utilized to assess passable emissions for mitigation methodologies.