The warming of the past

I picked this up via a weather forum. A commenter called Duncan MacAlister noticed that a graph of Atlantic Sea Ice extent had changed. He was comparing the graph according to to The Cryosphere Today's website with the same page on the Wayback Machine.

The two graphs were posted by a later commenter, and I've ripped them and reposted here:

 

So somewhere between the end of last year and now, something like a million square miles of sea ice have suddenly disappeared.

Global warming is pervasive stuff. It can even heat up the past.