title: Observed latitudinal variations in erosion as a function of glacier dynamics.
abstract: Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds.
authors.affiliation: Department of Geography, 1984 West Mall, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada.
authors.forename: Michéle
authors.initials: M
authors.lastname: Koppes
authors.affiliation: Department of Earth and Space Sciences and Quaternary Research Center, Box 351310, University of Washington, Seattle, Washington 98195-1310, USA.
authors.forename: Bernard
authors.initials: B
authors.lastname: Hallet
authors.affiliation: Department of Earth System Science, University of California, Irvine, California 92617, USA.|NASA Jet Propulsion Laboratory, Pasadena, California 91109, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Rignot
authors.affiliation: Department of Earth System Science, University of California, Irvine, California 92617, USA.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Mouginot
authors.affiliation: Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204, USA.
authors.forename: Julia Smith
authors.initials: JS
authors.lastname: Wellner
authors.affiliation: School of Oceanography, Box 357940, University of Washington, Seattle, Washington 98195-7940, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Boldt