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Earth's Temperature Is Hottest in Centuries
Scientists Blame 'Human Activities' for Warming Trend
By JOHN HEILPRIN, AP
WASHINGTON (June 22) -- The Earth is the hottest it has been in at least 400
years, probably even longer. The National Academy of Sciences, reaching that
conclusion in a broad review of scientific work requested by Congress,
reported Thursday that the "recent warmth is unprecedented for at least the last
400 years and potentially the last several millennia."
A panel of top climate scientists told lawmakers that the Earth is heating
up and that "human activities are responsible for much of the recent warming."
Their 155-page report said average global surface temperatures in the
Northern Hemisphere rose about 1 degree during the 20th century.
This is shown in boreholes, retreating glaciers and other evidence found in
nature, said Gerald North, a geosciences professor at Texas A&M University
who chaired the academy's panel.
The report was requested in November by the chairman of the House Science
Committee, Rep. Sherwood Boehlert, R-N.Y., to address naysayers who question
whether global warming is a major threat.
Last year, when the House Energy and Commerce Committee chairman, Rep. Joe
Barton, R-Texas, launched an investigation of three climate scientists,
Boehlert said Barton should try to learn from scientists, not intimidate them.
Boehlert said Thursday the report shows the value of having scientists
advise Congress.
"There is nothing in this report that should raise any doubts about the
broad scientific consensus on global climate change," he said.
Other new research Thursday showed that global warming produced about half
of the extra hurricane-fueled warmth in the North Atlantic in 2005, and
natural cycles were a minor factor, according to Kevin Trenberth and Dennis Shea of
the Commerce Department's National Center for Atmospheric Research. Their
study is being published by the American Geophysical Union.
The Bush administration has maintained that the threat is not severe enough
to warrant new pollution controls that the White House says would have cost 5
million Americans their jobs.
Climate scientists Michael Mann, Raymond Bradley and Malcolm Hughes had
concluded the Northern Hemisphere was the warmest it has been in 2,000 years.
Their research was known as the "hockey-stick" graphic because it compared the
sharp curve of the hockey blade to the recent uptick in temperatures and the
stick's long shaft to centuries of previous climate stability.
The National Academy scientists concluded that the Mann-Bradley-Hughes
research from the late 1990s was "likely" to be true, said John "Mike" Wallace, an
atmospheric sciences professor at the University of Washington and a panel
member. The conclusions from the '90s research "are very close to being right"
and are supported by even more recent data, Wallace said.
The panel looked at how other scientists reconstructed the Earth's
temperatures going back thousands of years, before there was data from modern
scientific instruments.
For all but the most recent 150 years, the academy scientists relied on
"proxy" evidence from tree rings, corals, glaciers and ice cores, cave deposits,
ocean and lake sediments, boreholes and other sources. They also examined
indirect records such as paintings of glaciers in the Alps.
Combining that information gave the panel "a high level of confidence that
the last few decades of the 20th century were warmer than any comparable
period in the last 400 years," the academy said.
Overall, the panel agreed that the warming in the last few decades of the
20th century was unprecedented over the last 1,000 years, though relatively
warm conditions persisted around the year 1000, followed by a "Little Ice Age"
from about 1500 to 1850.
The scientists said they had less confidence in the evidence of temperatures
before 1600. But they considered it 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 were the
main causes of changes in greenhouse gas levels. But those temperature
changes "were much less pronounced than the warming due to greenhouse gas" levels
by pollution since the mid-19th century, it said.
The National Academy of Sciences is a private organization chartered by
Congress to advise the government of scientific matters.
06/22/06 12:40 EDT
Scientists Blame 'Human Activities' for Warming Trend
By JOHN HEILPRIN, AP
WASHINGTON (June 22) -- The Earth is the hottest it has been in at least 400
years, probably even longer. The National Academy of Sciences, reaching that
conclusion in a broad review of scientific work requested by Congress,
reported Thursday that the "recent warmth is unprecedented for at least the last
400 years and potentially the last several millennia."
A panel of top climate scientists told lawmakers that the Earth is heating
up and that "human activities are responsible for much of the recent warming."
Their 155-page report said average global surface temperatures in the
Northern Hemisphere rose about 1 degree during the 20th century.
This is shown in boreholes, retreating glaciers and other evidence found in
nature, said Gerald North, a geosciences professor at Texas A&M University
who chaired the academy's panel.
The report was requested in November by the chairman of the House Science
Committee, Rep. Sherwood Boehlert, R-N.Y., to address naysayers who question
whether global warming is a major threat.
Last year, when the House Energy and Commerce Committee chairman, Rep. Joe
Barton, R-Texas, launched an investigation of three climate scientists,
Boehlert said Barton should try to learn from scientists, not intimidate them.
Boehlert said Thursday the report shows the value of having scientists
advise Congress.
"There is nothing in this report that should raise any doubts about the
broad scientific consensus on global climate change," he said.
Other new research Thursday showed that global warming produced about half
of the extra hurricane-fueled warmth in the North Atlantic in 2005, and
natural cycles were a minor factor, according to Kevin Trenberth and Dennis Shea of
the Commerce Department's National Center for Atmospheric Research. Their
study is being published by the American Geophysical Union.
The Bush administration has maintained that the threat is not severe enough
to warrant new pollution controls that the White House says would have cost 5
million Americans their jobs.
Climate scientists Michael Mann, Raymond Bradley and Malcolm Hughes had
concluded the Northern Hemisphere was the warmest it has been in 2,000 years.
Their research was known as the "hockey-stick" graphic because it compared the
sharp curve of the hockey blade to the recent uptick in temperatures and the
stick's long shaft to centuries of previous climate stability.
The National Academy scientists concluded that the Mann-Bradley-Hughes
research from the late 1990s was "likely" to be true, said John "Mike" Wallace, an
atmospheric sciences professor at the University of Washington and a panel
member. The conclusions from the '90s research "are very close to being right"
and are supported by even more recent data, Wallace said.
The panel looked at how other scientists reconstructed the Earth's
temperatures going back thousands of years, before there was data from modern
scientific instruments.
For all but the most recent 150 years, the academy scientists relied on
"proxy" evidence from tree rings, corals, glaciers and ice cores, cave deposits,
ocean and lake sediments, boreholes and other sources. They also examined
indirect records such as paintings of glaciers in the Alps.
Combining that information gave the panel "a high level of confidence that
the last few decades of the 20th century were warmer than any comparable
period in the last 400 years," the academy said.
Overall, the panel agreed that the warming in the last few decades of the
20th century was unprecedented over the last 1,000 years, though relatively
warm conditions persisted around the year 1000, followed by a "Little Ice Age"
from about 1500 to 1850.
The scientists said they had less confidence in the evidence of temperatures
before 1600. But they considered it 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 were the
main causes of changes in greenhouse gas levels. But those temperature
changes "were much less pronounced than the warming due to greenhouse gas" levels
by pollution since the mid-19th century, it said.
The National Academy of Sciences is a private organization chartered by
Congress to advise the government of scientific matters.
06/22/06 12:40 EDT
Oh, yes, I know cranks, crackpots and fruitcakes still believe in perpetual motion and free energy. I just don't happen to believe in magic.
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