WASHINGTON - Scientists have discovered a significant, surprising warming of the world's oceans over the past 40 years, providing new evidence that computer models might be on target when they predict the Earth's warming.
The broad study of temperature data from the oceans, dating to the 1950s, shows average temperatures have increased more than expected - about half a degree Fahrenheit closer to the surface, and one-tenth of a degree even at depths of up to 10,000 feet.
The findings, reported by scientists at the National Oceanic and Atmospheric Administration, also might explain a major puzzle in the global warming debate: why computer models have shown more significant warming than actual temperature data.
Global warming skeptics contend that if the computer models exaggerate warming that already has occurred, they should not be trusted to predict future warming. The models have shown higher temperatures than those found in surface and atmospheric readings. But now, the ocean data may explain the difference, scientists said.
In the administration study, scientists for the first time have quantified temperature changes in the world's three major ocean basins.
''We've known the oceans could absorb heat, transport it to subsurface depths, and isolate it from the atmosphere. Now we see evidence that this is happening,'' said Sydney Levitus, chief of the agency's Ocean Climate Laboratory and principal author of the study.
Levitus and fellow scientists examined temperature data from more than 5 million readings at various depths in the Pacific, Atlantic, and Indian oceans, from 1948 to 1996.
They found the Pacific and Atlantic oceans have been warming since the mid-1950s, and the Indian Ocean since the early 1960s, according to the study published today in the journal Science.
The greatest warming occurred from the surface to a depth of about 900 feet, where the average heat content increased by 0.56 degrees Fahrenheit. Water as far down as 10,000 feet was found to have gained on average 0.11 degrees.
''This is one of the surprising things. We've found half of the warming occurred below 1,000 feet,'' Levitus said. ''It brings the climate debate to a new level.''
