Reports: Ocean warming induced by humans

(CNN) -- The release of carbon dioxide and other greenhouses into the atmosphere has heated up the oceans over the last five decades, according to two new reports.

The scientists involved in the studies said the findings, based on climate modeling, correspond with actual ocean temperature measurements and will help better predict the effects of greenhouse warming in the future.

"I believe our results represent the strongest evidence to date that the Earth's climate system is responding to human-induced forcing," said Sydney Levitus of the National Oceanographic Data Center, lead author of one of the studies.

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Climatologists have long debated the role of oceans, which can absorb and store great amounts of heat, in the projected warming of the planet.

"Warming in the ocean is bad and good news. It really does add strength to the claims that global warming is here," said Tim Barnett of the Scripps Institute of Oceanography, lead author of the second report.

"But it also suggests that the immediate impact may not be as great because the oceans may slow things down a little," he said.

Oceans, which cover 72 percent of the planet, have been described as the "memory" of the world climate system. They can store large amounts of heat at great depths for thousands of years before it circulates back into the atmosphere.

In 2000, Levitus and other scientists concluded that the average ocean temperature had risen a fraction of a degree since 1955. But the team was unable to determine whether the change was just a natural variation or the result of human activities.

Simulating how the oceans should respond based on changes in greenhouse gas levels, the two models predicted a warming increase that corresponded closely with actual measurements.

While slight, the warming has penetrated down at least 3,000 meters (9,842 feet) below the surface, the scientists said.

"What we found is that the signal is so bold and big, that you don't have to do any fancy statistics to beat it out of the data. It's just there, bang. And the odds are exceedingly good that the model did not trick us with this signal," Barnett said.

The two reports will be published in the April 13 edition of the journal Science.

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NOAA National Oceanographic Data Center (NODC)
Scripps Institution of Oceanography

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