Charles J. Hanley of the AP  reported that in Canada’s Northwest Territories, the permafrost is melting and the Earth is burping out huge slugs of methane, one of the most potent of the greenhouse gases.  This methane has the potential to drive extremely rapid warming. It’s known as  a feedback loop: As more methane escapes, it traps more heat in the atmosphere, which in turn melts more permafrost, and so on.

The prospects are alarming enough [...]