Seth Borenstein Associated Press
May 7, 2015
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.
Fast facts
• Pushed by the burning of coal, oil and gas, global carbon dioxide levels aren’t
just higher, they are increasing at a record pace – 100 times faster than natural
rises in the past.
• 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.
