One of those wild cards is the 1,672 billion tonnes of carbon equivalent trapped in the form of methane in the Arctic permafrost, the soils kept frozen by the far North’s extreme temperatures. Methane is a powerful greenhouse gas—it has 20 times the warming effect of carbon dioxide—and the total amount of carbon equivalent in the Arctic permafrost is 250 times greater than annual U.S. greenhouse gas emissions. As the Arctic warms—which it’s doing rather rapidly—there’s a risk that the permafrost could become less than permanent, releasing some of that trapped methane into the air, which would then accelerate warming, leading to more Arctic melt, more methane emissions…so on and so on. Climate scientists call this a “feedback loop“—and if it happens soon, you could just call us screwed.
Read more in Time