Warming Arctic Permafrost Fuels Climate Change Worries – NYTimes.com

The problem of atmospheric carbon (CO2 and methane) may be much worse than we’d feared:

Experts have long known that northern lands were a storehouse of frozen carbon, locked up in the form of leaves, roots and other organic matter trapped in icy soil — a mix that, when thawed, can produce methane and carbon dioxide, gases that trap heat and warm the planet. But they have been stunned in recent years to realize just how much organic debris is there.

A recent estimate suggests that the perennially frozen ground known as permafrost, which underlies nearly a quarter of the Northern Hemisphere, contains twice as much carbon as the entire atmosphere….

If that permafrost melts because of global warming, it will release even more carbon gases into the atmosphere and so further accelerate global warming in a vicious cycle of positive feedback.

The experts also said that if humanity began getting its own emissions under control soon, the greenhouse gases emerging from permafrost could be kept to a much lower level, perhaps equivalent to 10 percent of today’s human emissions.

Even at the low end, these numbers mean that the long-running international negotiations over greenhouse gases are likely to become more difficult, with less room for countries to continue burning large amounts of fossil fuels.

In the minds of most experts, the chief worry is not that the carbon in the permafrost will break down quickly — typical estimates say that will take more than a century, perhaps several — but that once the decomposition starts, it will be impossible to stop.

via Warming Arctic Permafrost Fuels Climate Change Worries – NYTimes.com.