[cogitator]

It is difficult to play the global warming game unless you come up with a pausiable reason for the little freeze in the 1400s, which none of the Crackpots have yet to define. Most want to utilze volcano activity...but you can't explain almost 200 years of extremely cold weather in that fashion.

One plausible theory links this period of cooler global temperatures to reduced solar activity. There were three notable periods when sunspots were at a minimum between 1400 and 1850 -- the third minimum is called the "Maunder minimum", but I can't remember the names of the previous ones, which were not as long. Also, in the 1450s, the island of Kuwae in the Pacific had an extremly large eruption (Crater Lake - Mazama scale) that likely led to cooling for at least a decade and perhaps a bit longer.

[talleyman]

Don't forget that heat makes things expand - that's why the days are longer in the summer.

P.S. Broken hockey stick? Duck tape can fix that.