News from USA Today, April 11, 2013
The temperature of the Earth’s atmosphere has been essentially the same for the past decade or so, providing ammunition for skeptics of human-caused climate change. (This despite the fact that of the nine hottest years on record, eight have occurred since 2000, according to the National Climatic Data Center).
However, a recent study found that heat absorbed by the world’s oceans has increased significantly over the same period, prompting the study co-authors to say that the warming has been diverted and is heating the oceans instead of the atmosphere.
The study was published in the journal Geophysical Research Letters, a publication of the American Geophysical Union.
The current “hiatus” in atmospheric warming is temporary,says study co-author Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colo., during a telephone press conference Thursday morning. “Global warming is continuing but manifesting itself differently,” he says.
Here’s how scientists say global warming works: Increasing amounts of carbon dioxide and other gases caused by the burning of the oil, gas and coal that power our world are enhancing the natural “greenhouse effect,” causing the temperature of the atmosphere and oceans to warm to levels that climate scientists say cannot be linked to natural forces.
“Over 90% of the heat trapped by greenhouse gases winds up warming the oceans,” said Josh Willis, a scientist with NASA’s Jet Propulsion Laboratory during the press conference. “Oceans cover two-thirds of the earth’s surface, so it’s expected that they’ll play a large role in how climate change and global warming play out.”
A large chunk of the warmth appears to be settling far down in the ocean about a half-mile beneath the surface, Trenbreth says. New technology over the past decade or so have allowed scientists to better measure the temperature of the deep oceans, Willis says.
While the world’s excess heat comes from climate change, the amount that’s absorbed into the oceans (as opposed to staying in the atmosphere) appears to be due to natural changes in climatic wind and ocean patterns, according to the study.
Temporary pauses and restarts in atmospheric temperature shouldn’t detract from the main story: “The planet is warming, climate change is happening and the primary cause is greenhouse gases released by human activities,” Willis says.