The law of the landscape for glaciers

Fast glaciers are much more effective at gouging landscapes than slow-moving ones, a new study finds. The results may explain a phenomenon that has long puzzled scientists - why long-term erosion rates from glaciers are so much lower in Polar Regions, where glaciers move more slowly.

The world over, glaciers erode the land at variable rates, with some of the most rapid glacial erosion happening in mid-latitude climates.

This process has been ongoing for ages, carving out valleys, fjords and mountains, yet scientists don't fully understand it, in part because studying the ice-bedrock interface of glaciers is so difficult.

Here, Frederic Herman et al. focused on the Franz Joseph Glacier in New Zealand, studying its movement over a five-month period in 2013 and 2014 with remote sensing. At the same time, they quantified erosion rates beneath the glacier using observations of the amount of sediment discharged at its edge.

With the velocity and erosion data, the researchers constructed a law for glacial erosion that captures the variability seen globally, in different climate zones.

Their work reveals erosion to be highly sensitivity to small variations in topographic slope and precipitation, the researchers say, and it suggests that fast glaciers are more effective landscape gougers than their slow-moving counterparts.

The results of Herman et al. help explain the impact of glaciation on mountainous landscapes during Earth's history.

"Erosion by an Alpine glacier," by F. Herman; M. Brughelli; S.N. Lane; T. Adatte at University of Lausanne in Lausanne, Switzerland; O. Beyssac at Sorbonne Universites in Paris, France; O. Beyssac at CNRS in Paris, France; O. Beyssac at Museum National d'Histoire Naturelle in Paris, France; S. Leprince; J.Y.Y. Lin; J.-P. Avouac at California Institute of Technology in Pasadena, CA; S.C. Cox at Institute of Geological and Nuclear Survey Science in Dunedin, New Zealand.