Climate stability has never been a feature of planet Earth. The only constant about climate is change; it changes continually and, at times, quite rapidly. Many times in the past, temperatures were far higher than today, and occasionally, temperatures were colder. As recently as 6,000 years ago, it was about 3C warmer than now. Ten thousand years ago, while the world was coming out of the thou-sand-year-long "Younger Dryas" cold episode, temperatures rose as much as 6C in a decade -- 100 times faster than the past century's 0.6C warming that has so upset environmentalists.

 Source : Canada.com