Rise in methane detected above Arctic

Experts not sure if it’s melting permafrost, or something less troubling

OSLO – A rise in concentrations of a powerful greenhouse gas over the Arctic after a decade of stability is stirring worries about a possible thaw of vast stores trapped in permafrost, experts said.

Levels of methane in the atmosphere rose 0.6 percent in 2008, according to preliminary data from the Zeppelin station on a remote island in the Norwegian Arctic, after a similar 0.6 percent gain in 2007, Norwegian officials said.

The 2007 rise outpaced a global rise in methane of 0.34 percent to a new record high after levels had been stable for about a decade. World data for 2008 are not yet available.