(From The New York Times, 4/25/89, p. C4) WARMING OF OCEANS SPURS CONCERN OVER SHIFT IN CL

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(From The New York Times, 4/25/89, p. C4) WARMING OF OCEANS SPURS CONCERN OVER SHIFT IN CLIMATE By William K. Stevens Government scientists, employing satellites and advanced methods of measurement, have found that the average surface temperature of the world's oceans rose more than 1 degree Fahrenheit from 1982 to 1988. By comparison, the earth's surface has warmed about 9 degrees since the end of the last Ice Age 12,000 years ago. A 1-degree increase in less than a decade is considered extremely large, climatologists said, and it would be alarming if it were to continue at that rate for a long time. Scientists believe that the greenhouse effect, in which increasing levels of carbon dioxide and other gases combine with moisture to trap heat inside the earth's atmosphere, will cause a further rise of 2 to 9 degrees in the global temperature by the middle of the next century. The result, they say, could be serious dislocations of the earth's climate. No one contends that the increases in ocean temperature detected in the 1980's are caused by the greenhouse effect for sure. And some scientists believe that the readings were skewed because a Mexican volcano, El Chichon, erupted in 1982. But climatologists said that while the findings did not prove global warming, they were consistent with it. "It's too soon to tell" whether the new readings say anything about climatic trends, said A. E. Strong of the National Oceanic and Atmospheric Administration, who reported them in the current issue of the British journal Nature. "If this trend continues at the same rate for another six or eight years, we're going to be concerned that a significant portion of this is a result of global warming," he said. "But it could easily cool off, and we could see just a short-term cycle." Dust from a Volcano The measurements were made by infrared sensors aboard NOAA satellites that take readings at 2.5 million to 3 million points in the ocean. This compares with some 50,000 conventional thermometer readings taken aboard ships and buoys. In this respect, he said, the satellite coverage is superior. But the eruption of El Chichon in 1982 sent so much dust into the air that it would have distorted the satellite readings and produced lower temperatures, said Dick Reynolds, who analyzes satellite and ship readings for the National Weather Services Climate Analysis Center. This, climatologists say, would have guaranteed a rise after 1982, as the dust cleared. Mr. Reynolds said that data from ships and buoys showed almost no trend during that period. Dr. Strong said that from 1984 on, dust from El Chichon was not a factor, and that the trend after that, as measured by satellite, was essentially the same as for the entire 6.5 years. Over the whole period, he said, the average temperature of the ocean outside the polar regions rose to 36.8 degrees, from 35.5 degrees. Insofar as the satellite readings are accurate, a six-year trend "is really very short compared with the ups and downs we've seen" over the long term, said Kirk Bryan, a climatologist at the Geophysical Fluid Dynamics Laboratory at Princeton University. He noted in particular a dramatic warming trend in the 1930's in the Northern Hemisphere and a cooling trend in the 1960's. "We still haven't explained why those events occurred," he said. In the Northern Hemisphere, the 1930's were about 1 degree warmer than the 1960's. Dr. Strong holds that ocean measurements are a more accurate gauge of temperature change on a global scale because cities are "heat islands" and distort land measurements. Before 1982, he said, sensing instruments aboard satellites were unable to deal with the distorting effect of temperature measurements of moisture in the earth's atmosphere. The latest instruments, he said, are able to do that. The sea-level readings from buoys are still used, he said, not least to help calibrate the satellite-borne sensors. And in any case, he said, the satellites have put climatologists and meteorologists in a much better position to assess change as it unfolds.

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