Younger Dryas

The Younger Dryas was a sudden return to cold conditions that interrupted the warming at the end of the last ice age. Beginning roughly thirteen thousand years ago, temperatures in the North Atlantic region fell sharply for around twelve centuries, and glaciers advanced again in parts of Europe and North America. It then ended abruptly, with a warming of several degrees in a few decades. The leading explanation is that a flood of fresh meltwater from the North American ice sheets disrupted the ocean currents that carry warmth northwards, although other causes, including a cosmic impact, have been proposed and are disputed. The period is named after the Dryas octopetala, an Arctic flower whose pollen spread in cold periods.

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