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Temperatures in the contiguous United States last year were the hottest in more
than a century of record-keeping, shattering the mark set in 1998 by a wide
margin, the federal government announced.
The average temperature in 2012 was 55.3 degrees, one degree above the previous
record and 3.2 degrees higher than the 20th-century average, scientists at the
National Oceanic and Atmospheric Administration said. They described the data as
part of a longer-term trend of hotter, drier and potentially more extreme
weather.
The higher temperatures are due in part to cyclical weather patterns, according
to the scientists. But the researchers also said the data provided further
compelling evidence that human activity — especially the burning of fossil
fuels, which produces greenhouse gases — is contributing to changes in the U.S.
climate.
The new report has broad ramifications for policy — and everyday life. Americans
who might have thought climate change was a problem for the distant future are
experiencing warmer temperatures in their own lifetimes — “something we haven’t
seen before,” said Thomas R. Karl, who directs NOAA’s National Climatic Data
Center. “That doesn’t mean every season and every year is going to be breaking
all-time records, but you’re going to see this with increasing frequency.”
Temperatures were above normal for every month from June 2011 to September 2012,
a 16-month stretch that had not occurred since the government began keeping
records in 1895. Alaska and the Pacific Northwest did not have record-setting
heat last year; a cool-weather pattern over the Pacific Ocean kept temperatures
lower.
Tuesday’s report did not address global temperatures. Still, the NOAA analysis
has triggered an intense debate over whether global temperatures will reach
dangerous levels by the century’s end. In 2009, the world’s leaders pledged to
keep global temperatures from rising above pre-industrial levels by two degrees
Celsius, or 3.6 degrees Fahrenheit. Now many experts say that goal may be out of
reach.
“A hundred years from now, they’re not going to be talking about health care or
the fiscal cliff,” said Vanderbilt Law School professor Michael Vandenbergh.
“But they will ask, ‘What did you do when we knew we were going to have serious
climate change?’ ”
Not all scientists see the situation as urgent. John R. Christy, who directs the
Earth System Science Center at the University of Alabama at Huntsville, said
some researchers are exaggerating the threat of climate change. He added that
the right climate target is “in the mind of the beholder,” given that rising
energy demand is a sign that many poor people are struggling “to be lifted out
of their current condition.”
“No one in Washington can stop that,” he said. “And, right now, carbon is the
most accessible and affordable way to supply that energy — so CO2 emissions will
continue to rise because of the undeniable benefit carbon energy brings to human
life.”
Judith A. Curry, an atmospheric scientist at the Georgia Institute of
Technology, said in an e-mail that it is premature to blame droughts or
hurricanes on human-caused warming. “Natural variability continues to dominate
the occurrence of extreme weather events,” she said.
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