1996: year of warmth and weather reversals.

Recalling last year's icy winter and mild summer, residents of the eastern United States and Europe might guess that 1996 was a cool year around the globe. Actually, those regions were out of step with the planet as a whole, which posted near-record high temperatures, report British and U.S. researchers.

The balminess of 1996 followed record-breaking warmth in 1995, 1991, and 1990, making the 1990s the hottest decade in more than a century. Although climate scientists refrain from attributing the rising global temperatures to greenhouse gas pollution, they say the trend is consistent with their predictions.

Averaged around the globe, Earth's surface temperature in 1996 was among the top 10 since reliable measurements began in 1860, say researchers at the University of East Anglia in Norwich, England, and the British Meteorological Office in Bracknell. These scientists track temperature readings taken by more than 1,000 weather stations on land and a similar number of ships and buoys at sea. Although their data for December remain preliminary, they calculate that the globe in 1996 was 0.21#161#C warmer than average, which they define as the mean temperature between 1961 and 1990.

The values for 1996 fell short of the record year, 1995, which hit 0.40#161#C above the average, says Phil Jones of East Anglia. Researchers at NASA's Goddard Institute for Space Studies in New York find that 1996 sits within the top five warmest years in their record of temperatures reaching back to 1866. The NASA scientists track measurements of surface temperatures taken at some 2,000 meteorological stations on land and satellite records of ocean temperatures for recent years. They find that the global temperature in 1996 was 0.32#161#C above the average for 1951 through 1980.

A different picture of climate emerges from satellite measurements that reflect conditions between the ground and an altitude of 7 kilometers. In the 18-year-long record of satellite data, 1996 registered as the eighth coldest year, says John Christy of the University of Alabama in Huntsville. The atmosphere last year was slightly cooler than average, relative to the years 1982 through 1991.

The discrepancy between surface and atmospheric data has persisted for several years, making it difficult for scientists to interpret the climate's recent behavior. The British record shows Earth's surface warming at a rate of 0.17#161#C per decade, whereas the satellite records show the atmosphere cooling slightly, at 0.035#161#C per decade.

Because the satellite measurements track a broad layer of the atmosphere, they need not match what is happening at Earth's surface, says James Hurrell of the National Center for Atmospheric Research in Boulder, Colo. "They give different perspectives. There is no reason to expect that the trends should be the same over the short period since 1979. But over the long haul, we would expect the temperature trends to come into better agreement," he says. One area of accord between satellite and surface data is the pattern of temperatures that developed last year. A temporary climatic pattern known as La Nina-the reverse of El Nino-chilled the central equatorial Pacific. Cool weather also dominated in the central and eastern United States, northern Europe, and parts of Canada and Russia. Much of the rest of the globe, including Greenland, was warm. This pattern represents a reversal of the one that has dominated since 1980.

Computer climate models predict that the buildup of heat-trapping pollution will warm Earth's surface over time, though natural variations can make individual years warm or cold. A consensus of scientists projected last year that the average global surface temperature will climb somewhere between 1#161#C and 3.5#161#C by the year 2100.

In the short term, James E. Hansen of NASA predicts, the globe will set a new temperature record before the end of the century. - R. Monastersky