Earth hottest now in last 400 years
(AP)
Updated: 2006-06-23 09:39
It had compared the sharp curve of the hockey blade to the recent uptick in
temperatures ¡ª a 1 degree rise in global average surface temperatures in the
Northern Hemisphere during the 20th century ¡ª and the stick's long shaft to
centuries of previous climate stability.
That research is "likely" true and is supported by more recent data, said
John "Mike" Wallace, an atmospheric sciences professor at the University of
Washington and a panel member.
Rep. Sherwood Boehlert, chairman of the House Science Committee, had asked
the academy for the report last year after the House Energy and Commerce
Committee chairman, Rep. Joe Barton aunched an investigation of the three
climate scientists.
The Bush administration has maintained that the threat from global warming is
not severe enough to warrant new pollution controls that the White House says
would have cost 5 million Americans their jobs.
"This report shows the value of Congress handling scientific disputes by
asking scientists to give us guidance," Boehlert said Thursday. "There is
nothing in this report that should raise any doubts about the broad scientific
consensus on global climate change."
The academy panel said it had less confidence in the evidence of temperatures
before 1600.
But it considered the evidence reliable enough to conclude there were sharp
spikes in carbon dioxide and methane, the two major "greenhouse" gases blamed
for trapping heat in the atmosphere, beginning in the 20th century, after
remaining fairly level for 12,000 years.
Between 1 A.D. and 1850, volcanic eruptions and solar fluctuations had the
biggest effects on climate. But those temperature changes "were much less
pronounced than the warming due to greenhouse gas" levels by pollution since the
mid-19th century, the panel said.
The National Academy of Sciences is a private organization chartered by
Congress to advise the government of scientific matters.
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