Global warming could get worse quickly if huge amounts of extra heat absorbed by the oceans are released back into the air: studyPosted by Jim at Monday, April 08, 2013
By Environment Correspondent Alister Doyle; Editing by Peter Graff
7 April 2013
OSLO (Reuters) – Climate change could get worse quickly if huge amounts of extra heat absorbed by the oceans are released back into the air, scientists said after unveiling new research showing that oceans have helped mitigate the effects of warming since 2000.
Heat-trapping gases are being emitted into the atmosphere faster than ever, and the 10 hottest years since records began have all taken place since 1998. But the rate at which the earth's surface is heating up has slowed somewhat since 2000, causing scientists to search for an explanation for the pause.
Experts in France and Spain said on Sunday that the oceans took up more warmth from the air around 2000. That would help explain the slowdown in surface warming but would also suggest that the pause may be only temporary and brief.
"Most of this excess energy was absorbed in the top 700 metres (2,300 ft) of the ocean at the onset of the warming pause, 65 percent of it in the tropical Pacific and Atlantic oceans," they wrote in the journal Nature Climate Change.
Lead author Virginie Guemas of the Catalan Institute of Climate Sciences in Barcelona said the hidden heat may return to the atmosphere in the next decade, stoking warming again.
"If it is only related to natural variability then the rate of warming will increase soon," she told Reuters.
Caroline Katsman of the Royal Netherlands Meteorological Institute, an expert who was not involved in the latest study, said heat absorbed by the ocean will come back into the atmosphere if it is part of an ocean cycle such as the "El Niño" warming and "La Niña" cooling events in the Pacific.
She said the study broadly confirmed earlier research by her institute but that it was unlikely to be the full explanation of the warming pause at the surface, since it only applied to the onset of the slowdown around 2000. […]
Last year was ninth warmest since records began in the 1850s, according to the U.N.'s World Meteorological Organization, and 2010 was the warmest, just ahead of 1998. Apart from 1998, the 10 hottest years have all been since 2000.
Guemas's study, twinning observations and computer models, showed that natural La Niña weather events in the Pacific around the year 2000 brought cool waters to the surface that absorbed more heat from the air. In another set of natural variations, the Atlantic also soaked up more heat. [more]