Previously sculpted landscapes accumulate ice more quickly than steep valleys

By Erin Wayman

Web edition: January 11, 2013
Print edition: February 9, 2013; Vol.183 #3 (p. 13)

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NATURE'S CARVER

Glaciers such as Switzerland's Aletsch Glacier (shown) pave the way for more extensive glaciations in the future by eroding wide, flat valleys into mountain landscapes.

Credit: Jean Braun

By carving wide valleys into mountain landscapes, glaciers prime a region for even more extensive glaciations in the future, researchers report in the Jan. 10 Nature.

Vivi Pedersen of Norway’s University of Bergen and David Egholm of Denmark’s Aarhus University simulated how mountain glaciers form when a climate grows colder. In mountains marked by steep, narrow valleys, ice volume steadily increases as temperatures drop and snow begins to fall at increasingly lower altitudes. But in flatter regions previously covered by glaciers, ice builds more rapidly because snow has more surface area to accumulate on.

The findings suggest a proliferation of mountain glaciers around 950,000 years ago occurred because earlier, smaller streams of ice had prepared areas for widespread glaciations.