Update, November 14, 2018: The authors of this study have acknowledged that their research contained inadvertent errors that make their conclusion about the amount of heat the ocean has soaked up less certain. They say corrections to the research will have a small impact on their calculations of overall heat uptake and provide larger margins of error.
The world’s oceans have soaked up much more excess heat in recent decades than scientists previously thought — as much as 60 percent more, according to a new study published in the journal Nature. The new research suggests the global could warm even faster in the coming decades than researchers originally predicted, The Washington Post reported.
The researchers, led by geoscientist Laure Resplandy of Princeton University, found that oceans absorbed 13 zettajoules — a joule, the standard unit of energy, followed by 21 zeroes — of heat energy each year between 1991 and 2016. Based on these findings, they argue, nations must reduce their greenhouse gas emissions 25 percent more than previously estimated if they hope to keep global warming below 2 degrees Celsius.
“Imagine if the ocean was only 30 feet deep,” Resplandy said in a statement. “Our data show that it would have warmed by 6.5 degrees C [11.7 degrees Fahrenheit] every decade since 1991. In comparison, the estimate of the last IPCC assessment report would correspond to a warming of only 4 degrees C [7.2 degrees F] every decade.”
Scientists have long struggled to quantify ocean warming before 2007 — the year that a network of robotic sensors known as Argo were deployed into the world’s oceans to track things like temperature and salinity. For pre-2007 data, the new research examined the volume of oxygen and carbon dioxide released from the oceans as they heated up, providing scientists an indicator for ocean temperature change.
“We thought that we got away with not a lot of warming in both the ocean and the atmosphere for the amount of CO2 that we emitted,” Resplandy told The Washington Post. “But we were wrong. The planet warmed more than we thought. It was hidden from us just because we didn’t sample it right. But it was there. It was in the ocean already.”