Amount of carbon dioxide in air keeps rising, hits milestone

Post date: May 10, 2015 1:47:25 AM

Amount of carbon dioxide in air keeps rising, hits milestone

By Seth Borenstein ASSOCIATED PRESS MAY 07, 2015

WASHINGTON — Global levels of carbon dioxide, the most prevalent heat-trapping gas, have passed a daunting milestone, federal scientists say.

The National Oceanic and Atmospheric Administration says 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.

The dashed red line with diamond symbols represents the monthly mean values,

centered on the middle of each month. The black line with the square symbols represents the same,

after correction for the average seasonal cycle.

Click for a comparison with recent trends in carbon dioxide at Mauna Loa, Hawaii,

which has the longest continuous record of direct atmospheric CO2 measurements.