Is global heating hiding out in the oceans?

A press release from the Earth Institute at Columbia University: A recent slowdown in global warming has led some skeptics to renew their claims that industrial carbon emissions are not causing a century-long rise in Earth’s surface temperatures. But rather than letting humans off the hook, a new study in the leading journal Science adds support to the idea that the oceans are taking up some of the excess heat, at least for the moment. In a reconstruction of Pacific Ocean temperatures in the last 10,000 years, researchers have found that its middle depths have warmed 15 times faster in the last 60 years than they did during apparent natural warming cycles in the previous 10,000.

“We’re experimenting by putting all this heat in the ocean without quite knowing how it’s going to come back out and affect climate,” said study coauthor Braddock Linsley, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. “It’s not so much the magnitude of the change, but the rate of change.”

...The IPCC scientists agree that much of the heat that humans have put into the atmosphere since the 1970s through greenhouse gas emissions probably has been absorbed by the ocean. However, the findings in Science put this idea into a long-term context, and suggest that the oceans may be storing even more of the effects of human emissions than scientists have so far realized.  “We may have underestimated the efficiency of the oceans as a storehouse for heat and energy,” said study lead author, Yair Rosenthal, a climate scientist at Rutgers University. “It may buy us some time – how much time, I don’t really know.  But it’s not going to stop climate change.”

...One explanation for the recent slowdown in global warming is that a prolonged La Niña-like cooling of eastern Pacific surface waters has helped to offset the global rise in temperatures from greenhouse gases.  In a study in the journal Nature in August, climate modelers at the Scripps Institution of Oceanography showed that La Niña cooling in the Pacific seemed to suppress global average temperatures during northern hemisphere winters but allowed temperatures to rise during northern hemisphere summers, explaining last year’s record U.S. heat wave and the ongoing loss of Arctic sea ice.

...The study’s long-term perspective suggests that the recent pause in global warming may just reflect random variations in heat going between atmosphere and ocean, with little long-term importance, says Drew Shindell, a climate scientist with joint appointments at Columbia’s Earth Institute and the NASA Goddard Institute for Space Studies, and a lead author on the latest IPCC report.  “Surface temperature is only one indicator of climate change,” he said. “Looking at the total energy stored by the climate system or multiple indicators--glacier melting, water vapor in the atmosphere, snow cover, and so on—may be more useful than looking at surface temperature alone.”...

CIA map of the Pacific Ocean, "by" Lasunncty, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license