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A GIANT meteorite crater that has turned up under the Greenland ice sheet may hold clues to a mini ice age some 13,000 years ago.

An international team found the 30-kilometre-wide feature using NASA radar data. It would have been made by a meteorite about 1 kilometre across.

A river draining from under the ice covering the crater is washing out sediment particles with a telltale internal structure that results from a brief shock wave. 鈥淭hey鈥檙e absolutely characteristic of impact,鈥� says team member Iain McDonald at Cardiff University, UK.

Without access to the crater, the team can only date the impact to some time in the past 3 million years (Science Advances, ). But that leaves open the possibility of a connection with a short episode of northern hemisphere cooling called the Younger Dryas, says McDonald.

Its cause has long been unclear. One theory involved an impact from space, but we knew of no suitable crater recent enough.

If the meteorite had hit ice hundreds of metres thick, millions of tonnes of fresh water would have melted and flowed into the sea. This could have disrupted ocean currents and cooled the climate, says McDonald.

This article appeared in print under the headline 鈥淚cy grave of huge meteorite discovered鈥�