Squirrels and beavers contributing to global warming more than previously thought

An arctic ground squirrel, not giving a damn about GW.

Arctic ground squirrels churn up and warm soil in the Tundra, releasing carbon dioxide, while methane released by beavers contributes 200 times more methane than they did 100 years ago, scientists say

Rodents such as squirrels and beavers are contributing far more to global warming than previously thought, forcing climate scientists to alter the models they use to chart how the world is warming up.

Arctic ground squirrels churn up and warm soil in the Tundra, releasing carbon dioxide, while methane released by beavers contributes 200 times more methane than they did 100 years ago, according to scientists from the American Geophysical Union.

Faeces and urine produced by rodents are speeding up the release of carbon from the permafrost, the vast store of greenhouses spanning the Arctic Circle, researchers found.

Dr Sue Natali, from the AGU, said "We know wildlife impacts vegetation, and we know vegetation impacts thaw and soil carbon.

"It certainly has a bigger impact than we've considered and it's something we will be considering more and more going into the future."

Dr Natali added: "Carbon has been accumulating in permafrost for tens of thousands of years. The temperature is very cold, the soils are saturated, so that when plants and animals die, rather than decompose, the carbon has been slowly, slowly building up.

"Right now the carbon storage is about 1,500 billion tonnes. To put that in perspective, that's about twice as much as is contained in the atmosphere."

As part of the Polaris Project, Dr Natali, from Woods Hole Research Center in Massachusetts, and Nigel Golden, from the University of Wisconsin travelled to Siberia to study the underground burrows of arctic squirrels.

The team found that this activity meant that the burrows were warmer than the surrounding ground, while nitrogen that the squirrels were adding to the ground through their waste was also having an impact.

Beavers, meanwhile, have dammed up more than 16,200 square miles of ponds. A separate paper, published in the journal AMBIO, found that beavers are responsible for releasing around 881,000 tons of methane into the atmosphere each year, much more cud-chewing animals such as deer or antelope.

It means scientists will in the future have to alter their theories around anthropogenic, or man-made, climate change to take account of 'rodentopogenic' influences, scientists told Mail Online.

A paper by Dr Natali and Dr Golden, to be presented to the AGU, says: "While this fertiliser can counteract greenhouse gas loss by causing plants to grow, which then soak up carbon dioxide from the atmosphere, it can also feed microbes in the soil, accelerating the amount of carbon dioxide and methane - both greenhouse gases - that are being released."

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