Glacier expert warns that climate is warming abruptly

A renowned glacier expert says the earth’s climate has passed a tipping point and entered a period of rapid warming that may threaten human civilization. Other than that, he’s a barrel of laughs. Lonnie Thompson, who has taken core samples from glaciers for 23 years, suggests that the cool period humans had been enjoying until recently began with an abrupt change 5,200 years ago, which coincided with the rise of cities. About 50 years ago, conclude Thompson and eight other researchers in an article in the Proceedings of the National Academy of Sciences, our current abrupt warming spell began. The outlook isn’t pretty: Summarizing data from ice-core samples in the Andes and Himalayas, Thompson predicts that warming in the high mountains of the tropics “is unprecedented for at least two millennia” and that tropical-zone glaciers will melt completely “in the near future.” That means sea-level rises, more floods and droughts, and less reliable sources of freshwater — but maybe getting a tan will be a snap.