There's more than twice as much "tipping point" methane stored in the Arctic as previously estimated

The vast amount of carbon stored in the Arctic and boreal regions of the world is more than double that previously estimated, according to a study published this week. The new estimate is over 1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere.

http://www.globalcarbonproject.org/news/SoilOrganicPoolsinPermafrost.html