Antarctica's sea ice has melted so fast — and the Earth has remained so much warmer than usual — that scientists are sounding a global alarm. The reason is simple: Antarctic sea ice that always comes back after first melting has not returned. Vast regions of Antarctic coast are exposed that were never bare before.
As physical oceanographer Edward Doddridge put it, referring to this development as "unprecedented" simply "isn't strong enough. For those of you who are interested in statistics, this is a five-sigma event. So it's five standard deviations beyond the mean."
