The study was carried out on Jakobshavn Isbrae, a tongue of ice that extends into the sea from Greenland’s west coast. Aerial and satellite images of the glacier indicate that it has retreated about 40 kilometres since 1850. But when the researchers reconstructed its advance during the Little Ice Age, which took place 200 years ago, they discovered that it had expanded at about the same rate.

Reconstructing the glacier’s earlier behaviour involved collecting sediment samples from Glacial Lake Morten and Iceboom Lake, a pair of glacier-fed lakes that sit along the glacier’s path of expansion.

As Jakobshavn Isbrae advanced towards the sea, it reached the former lake first, damming it on one side and filling what had once been a tundra-covered valley with meltwater. After counting sediment layers and carbon-dating the fossilised remains of the tundra vegetation, the scientists concluded that the lake formed between 1795 and 1800. Analysis of sediments at the bottom of Iceboom Lake suggested that the glacier reached it about 20–25 years later.

‘Our results support growing evidence that calving glaciers are particularly sensitive to climate change,’ said Jason Briner, who led the research.

September 2011