Not gonna get involved in the Global Warming bit, but..

The period from approx. 1300-1800s was called a 'mini ice-age', where the average temp was lower than usual. Don't have the details (one of those Science/Discovery/History Channel shows), but that could be the Dickens skating bit..;)

I wish I'd said that.. The Staircase Wit

anahl nathrak uth vas betude doth yel dyenvey..;)