Continuous permafrost dominates the northern stretches of the Arctic, where temperatures are coldest. South of this area, permafrost breaks up into patches that make up the discontinuous zone. Places with even less permafrost comprise two more zones, called sporadic and isolated. Far north, where the permafrost is continuous, the lower layer is stable, extending hundreds and even thousands of feet down—2,400 feet in some parts of northern Alaska and as much as 5,000 feet in northern Siberia. But in the more southern, discontinuous reaches of the permafrost zone, the frozen layer is only a foot to several feet thick, making it susceptible to warming temperatures.
When organic matter degrades in dry air, carbon dioxide is emitted. And in wet soil or underwater, where there is little or no molecular oxygen, anaerobic bacteria break down the organic materials and give off methane. Both CO2 and methane are greenhouse gases. As they are released into the atmosphere from permafrost, scientists predict that a disastrous cycle will emerge: The gases will trap hot air, raising the air temperature and melting the permafrost, releasing more carbon and further heating the planet.
According to a measure used by the IPCC called Global Warming Potential, methane will be responsible for producing 25 times as much heat as CO2 over the course of this century. But “there is going to be a significant impact whether carbon is released as CO2 or as methane,” says Edward Schuur, an ecosystem ecologist and lead author of the University of Florida study. Although methane’s molecular structure allows it to trap heat better than CO2, it is released more slowly into the atmosphere and dissipates at a faster rate.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.