By Damien Gayle
26 November 2012
As much as 44 billion tons of nitrogen and 850 billion tons of carbon could be released into the environment as permafrost thaws over the next century, U.S. government experts warn.
The release of carbon and nitrogen in permafrost could make global warming much worse and threaten delicate water systems on land and offshore, according to scientists from the U.S. Geological Survey.
It comes after the UN last week warned of record levels of carbon dioxide and other greenhouse gases in the atmosphere.
Billions of tonnes of greenhouse gases released into the atmosphere are likely to be trapped for centuries with far-reaching impacts for all life, it was warned.
But the latest figure suggests levels of carbon could double in 100 years, meaning that the increase in global temperatures will be likely to accelerate.
The previously unpublished nitrogen figure is useful for scientists making predictions with computer climate models, the researchers say, while the carbon estimate adds credence to other studies with similar findings.
“This study quantifies the impact on Earth's two most important chemical cycles, carbon and nitrogen, from thawing of permafrost under future climate warming scenarios,” said USGS Director Marcia McNutt.
“While the permafrost of the polar latitudes may seem distant and disconnected from the daily activities of most of us, its potential to alter the planet’s habitability when destabilised is very real.”
To generate the estimates, scientists studied how permafrost-affected soils, known as Gelisols, thaw under various climate scenarios, reporting their findings in the journal Geophysical Research Letters.
They found that all Gelisols are not alike. Some have soil materials that are very peaty, with lots of decaying organic matter that burns easily – these will impart newly thawed nitrogen into the ecosystem and atmosphere.
Other Gelisols have materials that are very nutrient rich – these will release a lot of nitrogen into ecosystems.
However, all Gelisols will contribute carbon dioxide and likely some methane into the atmosphere as a result of decomposition once the permafrost thaws – and these gases will contribute to global warming. […]