http://www.commondreams.org/headlines03/1204-04.htm
Published on Thursday,
December 4, 2003 by the San Francisco Chronicle
Climate Change Laid to Humans
Report Warns There's 'No Doubt' Industry is Primary
Cause
QUOTE:
"The two government experts said climate change
'may prove to be humanity's greatest challenge'
and warned that 'it is very unlikely to be adequately
addressed without greatly improved international cooperation
and action.'...Their published comments reflected the growing
concerns of most climate experts over the White House stance."
by David Perlman
New evidence found by teams of climate researchers leaves no doubt
that industrial emissions of greenhouse gases are responsible
for
increasing global temperatures -- an ominous trend that has
speeded up in the past 50 years and threatens to continue for
centuries, according to a report by two of the nation's leading
atmospheric scientists.
The two government
experts said climate change "may prove
to be humanity's greatest challenge" and warned that
"it is very unlikely to be adequately addressed without
greatly improved international cooperation and action."
Thomas Karl, a meteorologist at the National Climatic Data
Center in Asheville, N.C., and Kevin Trenberth, chief of
the climate analysis section at the National Center for
Atmospheric Research in Boulder, Colo., are publishing
their analysis in Friday's edition of the journal Science.
Neither scientist criticized
the Bush administration's refusal
to ratify the Kyoto treaty, which is designed to regulate
emissions of heat-trapping greenhouse gases worldwide.
But their published comments reflected the growing concerns
of most climate experts over the White House stance.
The two disagreed with
assertions by some scientists that
swings in worldwide temperatures over the years are normal
and natural. "Modern climate change is dominated by human
influences, which are now large enough to exceed the bounds
of natural variability," they said.
Karl and Trenberth
also agreed that many uncertainties
remained about how swiftly global temperatures are rising,
how much they are likely to rise and how long ago the
problem began.
However, "there
is no doubt," they say, "that the composition
of the atmosphere is changing because of human activities,
and today greenhouse gases are the largest human influence
on global climate.''
They estimate that
by the end of this century there is a
90 percent chance that the world's climate will heat up
between 3.1 and 8.9 degrees Fahrenheit because of those
human influences.
Among the consequences,
they predict, are more frequent
heat waves, more widespread droughts in some parts of the
world and "extreme precipitation events" in others.
They also predict more
wildfires, abrupt changes in vegetation
and continued melting of glaciers and of the great Greenland
Ice Sheet, causing floods along many continental coastlines.
Additionally, as snow
cover melts on land and icebergs
shrink at sea, both the darker ground and the darker ocean
surfaces will be exposed to solar radiation, increasing
temperatures even more, the climate forecasters say.
While some climate
analysts have noted that the vast
quantities of soot emitted by many industries and volcanic
eruptions can actually cool the atmosphere, that kind of
cooling can last only a few years, with little or no effect
on the long-range trend, the scientists say.
The report by Karl
and Trenberth adds new data to scores
of previous international studies and computer models of
future climate changes as well as analyses by the
Intergovernmental Panel on Climate Change.
The new conclusions
met with some disagreement Wednesday
from James Mahoney, a noted meteorologist and the Bush
administration's assistant secretary of commerce for oceans
and atmosphere, who directs all the government's weather
and climate research and forecasting agencies.
In a telephone interview,
Mahoney agreed that climate
change is indeed a global problem that "has no political
boundaries." He noted that the United States has a large
delegation of experts attending an international conference
on climate change in Milan right now.
Mahoney also insisted
that the United States under President
Bush had developed a "substantial involvement" in international
activities aimed at researching the problems of global warming
and at resolving their uncertainties.
But he took issue with
Karl's and Trenberth's insistence
that there's clear evidence that human activity far outstrips
natural variation as the main cause of global warming.
"That's their
assertion," Mahoney said. "They are extremely
competent, and there are many in the climate community who
would agree with them. That's not surprising, but there are
many others who would disagree with them. My own view is
somewhat more open-minded, and from my perspective we don't
really understand these things as well as we might.''
No one disputes that
there has been a sharp rise in carbon
dioxide levels in the atmosphere during the past decades,
Mahoney said, "but there remains disagreement about just
how severe its impact has been."
As to the grim future
that Karl and Trenberth see as a
result of global warming, "I do challenge them on that,"
Mahoney said, "because all future projections are based
on many, many models of how the atmosphere behaves,
and I think a number of skeptical scientists would
also challenge them."
©2003 San Francisco
Chronicle
###
