More than a trillion tons of methane lie trapped in permafrost and under frozen lakes in the Arctic. As the region thaws, the gas—a huge potential source of alternative energy—is bubbling out, simultaneously attracting venture capitalists and worrying climatologists. The U.S. Geological Survey estimates that methane locked in ice (known as hydrates) could contain more organic carbon than all the world’s coal, oil, and nonhydrate natural gas combined. But that isn’t the only reason to keep track of methane release. Because of the way methane absorbs warmth radiating from Earth, it is as much as 21 times more heat-trapping—and thus climate-warming—than carbon dioxide. Yet current models of climate change do not take into consideration the potential impact of methane.
Katey Walter, a researcher at the University of Alaska at Fairbanks, has spent the past few years mapping and measuring hot spots of methane emission in the rapidly melting regions of Alaska and Siberia. In a recent study, Walter and her team predict that if these methane reservoirs melt over the next 100 years, the gas released could re-create climate conditions that prevailed during a 2,500-year warming spell that began 14,000 years ago.
Walter mapped likely methane deposits across the region; quantified how much methane, formed when permafrost melts, is bubbling out of current lakes; and compared that with the amount emitted from methane-laden sediments taken from ancient frozen lakes. She determined that 11,000 years ago methane released from thawing lakes contributed 33 to 87 percent of atmospheric methane. After that, melting slowed for the next 9,000 years and the lakes refroze. But now due to global warming over the past 100 years, methane release in the Arctic seems to be accelerating, Walter says, and left unchecked, it will continue to rise well above the levels found 10,000 years ago.
A 386,000-square-mile tract of permafrost in Siberia contains as much as 55 billion tons of potential methane, Walter says —10 times the amount currently in the atmosphere. Several companies, including BMW, have expressed interest in methane-to-energy technologies for large-scale operations. Walter sees the benefits of using methane as an energy source as twofold: “Not only does it prevent a potent greenhouse gas from entering the atmosphere by converting it to weaker greenhouse gases—water vapor and carbon dioxide—but using it on-site would also reduce the demand for other fossil-fuel sources.”
