1995 captures record as warmest year yet.

Earth's average temperature in 1995 jumped to a new high in the 140-year-long record of reliable global measurements. At the same time, temperatures in the stratosphere dropped to a new low. Scientists say both records back up the idea that greenhouse gas pollution is altering Earth's climate.

The globally averaged surface temperature for 1995 climbed 0.4*C above the average from 1961 to 1990, edging out 1990 as the warmest year by four-hundredths of a degree Celsius, report researchers from the University of East Anglia in Norwich, England, and the United Kingdom's Meteorological Office in Bracknell. They included data collected from land stations, ships, and buoys.

The global temperature pattern was splotchy last year, with the readings furthest above average in the northern land areas, particularly Siberia and the western half of North America. Eastern North America, southern Europe, and northern Africa remained cool, according to the British records.

The warmth last year continues a 20-year trend of rising temperatures that has accelerated in the 1990s. The 5-year period from 1991 through 1995 is the warmest half decade in the record, surpassing the period of 1986 through 1990. "That's quite amazing," says East Anglia's Phil Jones, noting that the early 1990s was warm despite the eruption of Mount Pinatubo in June 1991, which chilled the globe for 3 years.

According to the British data, the globe has warmed by about 0.2*C per decade since 1975, an amount that appears consistent with estimates of future greenhouse warming made by supercomputers running global circulation models (GCM). In December 1995, the Intergovernmental Panel on Climate Change (IPCC) published a state-of-the-art assessment projecting a 2*C global warming by the year 2100.

The rising temperatures of late, says Jones, "suggest that these GCM estimates of how much the world is warming per decade are probably quite reasonable."

Measurements of atmospheric temperature by satellite, however, do not tell the same story as the surface data, says John Christy of the University of Alabama in Huntsville. Although he lacks data from December, Christy says that 1995 will rank only eighth warmest in the 17 years of temperature measurements from satellites. In fact, global temperatures read from space have actually decreased slightly since 1979.

Because they cover all areas of the globe, the satellites provide a more comprehensive picture of Earth's temperature. But they do not necessarily track conditions at ground level, where people live. The satellite instruments measure an average temperature through much of the lower atmosphere up to an altitude of 7 kilometers.

The globally averaged temperature, whether read by satellite or by surface stations, is only a crude measurement of the climate, says Jones. To monitor the planet more fully, scientists also analyze patterns of temperature change across different regions and seasons.

According to the IPCC report, pattern studies have produced evidence strong enough to conclude that pollutants-both the warmth-inducing greenhouse gases and cooling sulfur emissions-have played a role in producing recent patterns of climate change. "The balance of evidence suggests that there is a discernible human influence on global climate," says the report.

In searching for patterns, researchers examine temperatures in the stratosphere, 12 km to 50 km above the surface, where greenhouse gases are expected to produce a cooling. According to satellite measurements analyzed by Christy, temperatures in the lower stratosphere set a record low during 1995, averaging 0.4*C below average.

Stratospheric temperatures have declined markedly since 1991. Christy attributes the first few years of cooling to the debris that Mount Pinatubo blasted high into the air. But the cooling has continued long after Pinatubo's effects dwindled. Christy says the recent cooling could stem in part from ozone loss and from the accumulation of greenhouse gases in the lower atmosphere.