Pacific puts the brake on warming - cooling Pacific Ocean counteracts effects of global warming - Earth Science - Brief Article

Science News, March 8, 1997 by Richard Monastersky

Parts of the tropical Pacific Ocean have cooled over the last century, slowing the rate of global warming, according to a team of climate researchers. This reluctant section of the Pacific may explain why Earth has not warmed as quickly as expected, says Mark A. Cane of the Lamont-Doherty Earth Observatory in Palisades, N.Y.

Many computer simulations of Earth's climate have forecast a temperature rise twice as great as the current one. In the Feb. 14 Science, Cane and his colleagues look to the Pacific for answers. Using a computer model of the tropical ocean, they artificially warmed the climate and found that winds and ocean currents work to cool the eastern Pacific.

Even under natural conditions, the eastern equatorial Pacific tends to be cooler than the west because trade winds push warm surface water toward Indonesia and cause deeper, cool water to rise near Ecuador. The computer studies by Cane's team show that human-induced warming would enhance this natural cycle by strengthening the trade winds and the upwelling of cold water in the east. The much larger models used to study global climate lack enough resolution to simulate the ocean properly and thus do not show this process.

As evidence in support of their theory, the scientists point to records of sea surface temperatures over the last century. These show slight cooling in the eastern equatorial Pacific, while the global mean temperature has climbed about 0.4 degrees C.

Although this process may delay global warming, it can cause its own problems. Pacific cooling can disrupt global weather. Such cooling, say the researchers, "would likely have substantial social and economic consequences."