- WASHINGTON (AP) - Last year was the warmest on record for planet Earth, and for
the first time federal climate researchers are willing to say people are
at least partly to blame.
- ``I wouldn't have been willing to say
this two years ago. I believe we are seeing evidence of global warming
at least some of which is attributable to human activities,'' said Elbert
W. Friday, research chief of the National Oceanic and Atmospheric Administration.
- ``Indeed, 1997 was the warmest year on
record,'' added Tom Karl, a senior NOAA researcher. ``The increasing trend
of temperatures that we see, we believe, is at least partially attributed
to human activities,'' such as pollution from cars and factories.
- Karl said the Earth's average temperature
last year was three-quarters of a degree Fahrenheit above normal. Normal
is 61.7 degrees, the average for the years 1961-1990.
- The 1997 reading tops the previous warmest
year, 1990, by 0.15 of a degree.
- Global warming has been a topic of sharp
debate in recent years, culminating in the climate conference last month
in Kyoto, Japan, where government officials from around the world sought
ways to reduce the potential impact of climate change.
- Many scientists believe that carbon dioxide
and other gases released into the atmosphere by industrial activities are
increasing the Earth's temperature by trapping heat from the sun, somewhat
like a greenhouse.
- Others disagree, and previously NOAA
officials simply reported their findings without speculating on the cause
of rising temperatures.
- ``We feel more comfortable now in saying
there is a human effect because we have more data than before,'' said Friday,
assistant NOAA administrator for oceanic and atmospheric research.
- ``The trend of global temperatures is
never due to a single source,'' commented Karl, noting that factors can
include periodic cycles of climate change, ocean circulation and even volcanoes.
- But, he added, ``the odds that we would
be wrong, that there is no relation to human activity, is in the area of
5 to 10 percent.''
- The rising temperatures have occurred
worldwide, Karl said, though the impact has been less in eastern North
America, China and eastern parts of the Mediterranean.
- This may be the result of sulfuric air
pollution in those areas, he commented, with the hazy air reflecting sunlight
and producing a local cooling effect much like that of the cloud generated
when the volcano Pinatubo erupted in the Philippines.
- That eruption shot sulfuric gases into
the upper atmosphere, producing a brief worldwide cooling.
- As far as the possible effects of global
warming are concerned, Friday noted there have been reports of softening
of the permafrost in Alaska and a 6-inch rise in overall ocean levels over
the last century.
- Karl said continued warming could produce
``a lot of surprises,'' including changes in rain and snowfall patterns,
though not necessarily a disaster.
- ``Based on the data we see, we certainly
couldn't predict a catastrophic event,'' he said.
- Karl said the El Nino phenomenon in the
Pacific Ocean, which is affecting weather in large areas, contributed to
the 1997 warming. El Nino is characterized by a large pool of warmer than
normal water in the Pacific.
- ``But even without El Nino, 1997 would
have been a very warm year,'' he added, noting that nine of the warmest
years on record have occurred in the last 11 years.
- ``This continues a trend that we see
in the records that date back to the 19th century, a trend of increasing
global temperatures, both on land and in the ocean.''
- Land temperatures have risen about 20
percent faster than ocean readings, he added.
- Karl's analysis was based on records
of land temperatures back to 1880 and ocean readings since 1900.