Warming Arctic Permafrost Fuels Climate Change Worries
A bubble rose through a hole in the surface of a frozen lake. It popped, followed by another, and another, as if a pot were somehow boiling in the icy depths.
Every bursting bubble sent up a puff of methane, a powerful greenhouse gas generated beneath the lake from the decay of plant debris. These plants last saw the light of day 30,000 years ago and have been locked in a deep freeze — until now.
“That’s a hot spot,” declared Katey M. Walter Anthony, a leading scientist in studying the escape of methane. A few minutes later, she leaned perilously over the edge of the ice, plunging a bottle into the water to grab a gas sample.
It was another small clue for scientists struggling to understand one of the biggest looming mysteries about the future of the earth.
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.
Temperatures are warming across much of that region, primarily, scientists believe, because of the rapid human release of greenhouse gases. Permafrost is warming, too. Some has already thawed, and other signs are emerging that the frozen carbon may be becoming unstable.
“It’s like broccoli in your freezer,” said Kevin Schaefer, a scientist at the National Snow and Ice Data Center in Boulder, Colo. “As long as the broccoli stays in the freezer, it’s going to be O.K. But once you take it out of the freezer and put it in the fridge, it will thaw out and eventually decay.”