Greenhouse gases increased sharply in 2007

April 26th, 2008 - 2:00 pm ICT by admin  

Washington, April 26 (IANS) Global levels of atmospheric carbon dioxide, the primary driver of climate change, increased by 0.6 percent or 19 billion tonnes last year. Additionally methane rose by 27 million tonnes after nearly a decade with little or no increase. National Oceanic And Atmospheric Administration (NOAA) scientists released these and other preliminary findings as part of an annual update on agency’s greenhouse gas index, which tracks data from 60 sites worldwide.

The burning of coal, oil and gas, known as fossil fuels, are the primary source of increasing carbon dioxide emissions. Earth’s oceans, vegetation, and soils soak up half of these emissions. The rest stays in the air for centuries or longer.

Twenty percent of the 2007 fossil fuel emissions of carbon dioxide are expected to remain in the atmosphere for thousands of years, according to the latest scientific assessment by the International Panel on Climate Change.

Viewed another way, last year’s carbon dioxide increase means 2.4 molecules of the gas were added to every million molecules of air, boosting the global concentration to nearly 385 parts per million (ppm). Pre-industrial carbon dioxide levels hovered around 280 ppm until 1850. Human activities pushed those levels up to 380 ppm by early 2006.

The rate of increase in carbon dioxide concentrations accelerated over recent decades along with fossil fuel emissions. Since 2000, annual increases of two ppm or more have been common, compared with 1.5 ppm per year in the 1980s and less than one ppm per year during the 1960s.

Methane levels rose last year for the first time since 1998. Methane is 25 times more potent as a greenhouse gas than carbon dioxide, but there’s far less of it in the atmosphere - about 1,800 parts per billion. When related climate affects are taken into account, methane’s overall climate impact is nearly half that of carbon dioxide, reports Sciencedaily.

Rapidly growing industrialisation in Asia and rising wetland emissions in the Arctic and tropics are the most likely causes of the recent methane increase, said scientist Ed Dlugokencky from NOAA’s Earth System Research Laboratory.

“We’re on the lookout for the first sign of a methane release from thawing Arctic permafrost,” said Dlugokencky. “It’s too soon to tell whether last year’s spike in emissions includes the start of such a trend.” Permafrost, or permanently frozen ground, contains vast stores of carbon.

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