Ice cores from arctic mountain glaciers show a dramatic climate change that began nearly 300 years ago, documenting an unprecedented increase in the intensity and duration of winter storms. Drilled by a Dartmouth-led team, the cores show striking changes in weather patterns that may have reached as far as Florida.“We attribute these changes to a warming of sea surface temperatures in the tropical Pacific,” says Erich Osterberg, an assistant professor in the Department of Earth Sciences at Dartmouth. “The North Pacific is very sensitive to what happens in the tropics. It is more stormy in Alaska now than at any time in the last 1,200 years, and that is driven by tropical ocean warming.”