blackfoot-valley

ago known as the Younger Dryas, which set continental glaciers to advancing again in what has been called the last gasp of the recent ice age. Although this cold spell has been known for some time, it wasn’t until the 1990s that researchers, using evidence from the annual layers in cores taken deep in the Greenland icecap, realized the rapidity of its onset - during only one to two decades. Our present interglacial period during the ten thousand years since that time was long thought to have been a rather uneventful warm period with mostly minimal variations. Recent research has uncovered evidence of sev- eral abrupt coolings lasting 800 years or so, followed by warmer periods of a millennium or more, in a cycle from cold to warm and back to cold averaging roughly 2,600 years. All this occurred within the general slow warming trend of the past 12,000 years covered by those studies. There is evidence of similar swings during the much longer time scale of 70,000 to 100,000 years of the last ice age. In recent historical times, there was also the “Little Ice Age” that pre- vailed from the 1400s to the mid-1800s. Analysis of Greenland Ice cores show this “cold snap” set in during less than two decades between 1400 and 1420. Some think it sealed the fate of the Norse Greenland settlements that had en- dured five hundred years from their founding by Eric the Red in the year 986, although there is clearly more to the story than just climate. (Their decline had started at least a century before the “Little Ice Age”.) 25