Scientists: Carbon dioxide at highest level in 800,000 years
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Perilous
Times and Climate Change
Scientists: Carbon dioxide at highest level in 800,000 years
By Seth Borenstein, Associated Press
WASHINGTON – The world's air has reached what scientists call a
troubling new milestone for carbon dioxide, the main global
warming pollutant.
Chris Carparelli adjusts a glass flask in an air sample processing
room at a NOAA lab in Boulder, Colo., on Wednesday. Researchers at
the lab measure the levels of carbon dioxide and other greenhouse
gases in air sent in weekly from sites that are part of an
international air sampling network.
Monitoring stations across the Arctic this spring are measuring
more than 400 parts per million of the heat-trapping gas in the
atmosphere. The number isn't quite a surprise, because it's been
rising at an accelerating pace.
Years ago, it passed the 350 ppm mark that many scientists say is
the highest safe level for carbon dioxide. It now stands globally
at 395.
So far, only the Arctic has reached that 400 level, but the rest
of the world will follow soon.
"The fact that it's 400 is significant," said Jim Butler, global
monitoring director at the National Oceanic and Atmospheric
Administration's Earth System Research Lab. "It's just a reminder
to everybody that we haven't fixed this, and we're still in
trouble."
Carbon dioxide is the chief greenhouse gas and stays in the
atmosphere for 100 years. Some carbon dioxide is natural, mainly
from decomposing dead plants and animals. Before the Industrial
Age, levels were around 275 parts per million.
For more than 60 years, readings have been in the 300s, except in
urban areas, where levels are skewed. The burning of fossil fuels,
such as coal for electricity and oil for gasoline, has caused the
overwhelming bulk of the man-made increase in carbon in the air,
scientists say.
It's been at least 800,000 years — probably more — since Earth saw
carbon dioxide levels in the 400s, Butler and other climate
scientists said.
Until now.
Readings are coming in at 400 and higher all over the Arctic.
They've been recorded in Alaska, Greenland, Norway, Iceland and
even Mongolia. But levels change with the seasons and will drop a
bit in the summer, when plants suck up carbon dioxide, NOAA
scientists said.
So the yearly average for those northern stations likely will be
lower and so will the global number.
Globally, the average carbon dioxide level is about 395 parts per
million but will pass the 400 mark within a few years, scientists
said.
The Arctic is the leading indicator in global warming, both in
carbon dioxide in the air and effects, said Pieter Tans, a senior
NOAA scientist.
"This is the first time the entire Arctic is that high," he said.
Tans called reaching the 400 number "depressing," and Butler said
it was "a troubling milestone."
"It's an important threshold," said Carnegie Institution ecologist
Chris Field, a scientist who helps lead the Nobel Prize-winning
Intergovernmental Panel on Climate Change. "It is an indication
that we're in a different world."
Ronald Prinn, an atmospheric sciences professor at the
Massachusetts Institute of Technology, said 400 is more a
psychological milestone than a scientific one. We think in
hundreds, and "we're poking our heads above 400," he said.
Tans said the readings show how much the Earth's atmosphere and
its climate are being affected by humans. Global carbon dioxide
emissions from fossil fuels hit a record high of 34.8 billion tons
in 2011, up 3.2 percent, the International Energy Agency announced
last week.
The agency said it's becoming unlikely that the world can achieve
the European goal of limiting global warming to just 2 degrees
based on increasing pollution and greenhouse gas levels.
"The news today, that some stations have measured concentrations
above 400 ppm in the atmosphere, is further evidence that the
world's political leaders — with a few honorable exceptions — are
failing catastrophically to address the climate crisis," former
Vice President Al Gore, the highest-profile campaigner against
global warming, said in an email. "History will not understand or
forgive them."
But political dynamics in the United States mean there's no
possibility of significant restrictions on man-made greenhouse
gases no matter what the levels are in the air, said Jerry Taylor,
a senior fellow of the libertarian Cato Institute.
"These milestones are always worth noting," said economist Myron
Ebell at the conservative Competitive Enterprise Institute. "As
carbon dioxide levels have continued to increase, global
temperatures flattened out, contrary to the models" used by
climate scientists and the United Nations.
He contends temperatures have not risen since 1998, which was
unusually hot.
Temperature records contradict that claim. Both 2005 and 2010 were
warmer than 1998, and the entire decade of 2000 to 2009 was the
warmest on record, according to NOAA.