Until recently, we had assumed that our climate was relatively stable. After all, for the past 10,000 years -- during which we developed the alphabet, electrical wiring, and microchip necessary for this article -- little has changed. But early-'90s research on Greenland's ice core proved that, over the past 100,000 years, climate stability has been the exception, not the norm. During the last glacial period, global temperatures fluttered up and down by as much as several degrees in as little as a decade. CO2 levels in the atmosphere changed along with the temperature, though more slowly.