Seth Borenstein of The Associated Press
WASHINGTON – Global levels of carbon dioxide, the most prevalent
heat-trapping gas, have passed a daunting milestone, federal scientists
report.
The National Oceanic and Atmospheric Administration said that in
March, the global monthly average for carbon dioxide hit 400.83 parts
per million. That is the first month in modern records that the entire
globe broke 400 ppm, reaching levels that haven’t been seen in about 2
million years.
“It’s both disturbing and daunting,” said NOAA chief greenhouse gas
scientist Pieter Tans. “Daunting from the standpoint on how hard it is
to slow this down.”
He said it is disturbing because it is happening at a pace so fast
that it seems like an explosion compared to Earth’s slow-moving natural
changes.
Carbon dioxide isn’t just higher, it is increasing at a record pace,
100 times faster than natural rises in the past, Tans said.
Pushed by the burning of coal, oil and gas, global carbon dioxide is
18 percent higher than it was in 1980, when NOAA first calculated a
worldwide average. In 35 years, carbon dioxide levels rose 61 parts per
million. In pre-human times, it took about 6,000 years for carbon
dioxide to rise about 80 parts per million, Tans said.
Monthly levels fluctuate with the season, peaking in May and then
decreasing as plants absorb carbon dioxide. But they are increasing on a
year-to-year basis.
Levels are also higher in the Northern Hemisphere because that’s
where carbon dioxide is being spewed by power plants and vehicles, Tans
said.
The first time levels passed the 400 ppm milestone was for just a few
weeks in the Arctic in 2012. Last year the monthly Northern Hemisphere
average measured in Hawaii exceeded 400 and now the global average has
as well, said James Butler, head of NOAA’s global monitoring division.
© Copyright 2015 Union-Bulletin, 112 S. First Ave., Walla Walla, WA
99362/509-525-3300. All rights reserved.
http://union-bulletin.com/news/2015/may/07/carbon-dioxide-levels-atmosphere-reach-2-million-y/
|