Greenhouse gases reach record levels

(UPI) -- The amount of greenhouse gases in the atmosphere has reached record highs in 2012 resulting in a 32 percent increase in radiative forcing -- the warming effect on our climate -- since 1990.

According to the World Meteorological Organization (WMO), carbon dioxide accounted for 80 percent of this increase while methane and nitrous oxide accounted for the balance.

The increase in atmospheric carbon dioxide between 2011 and 2012 was higher than its average growth over the last decade.

“As a result of this, our climate is changing, our weather is more extreme, ice sheets and glaciers are melting and sea levels are rising,” said WMO Secretary General Michel Jarraud. The concentration of carbon dioxide was 393.1 parts per million in 2012, a rise of 2.2 ppm over 2011. This was above the yearly average increase of 2.02 ppm over the past ten years.

Since 1750, CO2 levels have increased by 41 percent, methane by 160 percent and nitrous oxide by 20 percent. Half the CO2 emitted by the burning of fossil fuels lingers in the atmosphere, while the rest is absorbed by plants.

Forty percent of methane emissions can be attributed to natural causes -- wetlands and termites -- while 60 percent are attributable to human activities including cattle breeding, fossil fuel exploitation and biomass burning.

“Limiting climate change will require large and sustained reductions of greenhouse gas emissions,” said Jarraud. “Time is not on our side.”

He added that unprecedented atmospheric carbon levels are the result of human activities and that “if we continue business as usual,” global average temperature may be 4.6 degrees higher by the end of this century than pre-industrial levels.

WMO’s annual Greenhouse Gas Bulletin tracks only the atmospheric concentrations of gases, and not emissions.