Record levels of carbon dioxide

Scientist says gas in atmosphere rising at accelerated rate

Jim Erickson, Rocky Mountain News

Published April 21, 2006 at midnight

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Atmospheric levels of carbon dioxide, the gas largely blamed for global warming, have hit record highs and appear to be rising at an accelerating rate, a Boulder scientist said Thursday.

Each year the burning of fossil fuels pumps more than 7 billion tons of carbon into the air in the form of heat-trapping carbon dioxide gas, or CO2 .

The preindustrial carbon dioxide level was 278 parts per million. The current concentration just hit a record 381 ppm, said Pieter Tans, an atmospheric scientist with the National Oceanic and Atmospheric Administration in Boulder. That's a 37 percent increase.

"Emissions continue to grow, and so does CO2 ," Tans said Thursday.

"In the long run, this whole problem of climate change will be dominated by CO2.

"If we do not tackle CO2 emissions, we'll get nowhere."

Air samples from around the world are analyzed at Tans' lab to determine levels of carbon dioxide and other heat-trapping "greenhouse" gases.

Between 1959 and 1963, levels of carbon dioxide increased at a rate of 0.76 ppm per year at Hawaii's Mauna Loa, Tans said.

During that period, about 2.5 billion tons of carbon were pumped into the air each year through fossil-fuel combustion.

From 2001 to 2005, the annual carbon dioxide growth rate averaged 2.1 ppm.

During that span, an estimated 7.3 billion tons of carbon were emitted worldwide each year.

In 2005, levels of carbon dioxide on Mauna Loa increased at 2.53 ppm, the third-fastest annual rise since record-keeping began.

"It appears to be accelerating," Tans said of the atmospheric CO2 buildup.

He will present his findings Wednesday at a meeting of atmospheric scientists in Boulder.

"What we're seeing in the atmosphere reflects the fact that we're burning more fossil fuel and we're burning it faster," said NOAA atmospheric scientist Russell Schnell.

Air bubbles trapped in ancient polar ice show that carbon dioxide levels are higher today than at any time in more than 450,000 years.

The Earth has warmed about 1 degree Fahrenheit over the past century. Most scientists believe human activities - mainly the burning of fossil fuels - are partly to blame.

Computer models predict the warming will accelerate.

By 2100, global temperatures are expected to rise 2.5 to 10.4 degrees Fahrenheit, according to the Intergovernmental Panel on Climate Change.

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