30th January 2015
Guest Writer for Wake Up World
The graphic shows the vast swathe of our planet that geologists call the Younger Dryas Boundary Field. The tell-tale traces of multiple impacts by the fragments of a giant comet have been found across this huge “fingerprint”, spanning North America, Central America, parts of South America, most of Europe and parts of the Middle East as well. Some of these comet fragments were two kilometres or more in diameter.
They are estimated to have hit the Earth like a blast from a cosmic scatter-gun around 12,800 years ago. This was near the end of the last Ice Age, from which our world had been emerging into a pleasant warming phase, but these impacts set in train a kind of “nuclear winter” and plunged the planet back into a period of deep cold and darkness that lasted until around 11,500 years ago. It is this period of extreme cold that is referred to as the Younger Dryas (after a characteristic Alpine tundra wildflower, Dryas octopetala) but it is only now, with conclusive evidence of the comet impact, that we can be sure what caused it.