title: Calving rates at tidewater glaciers vary strongly with ocean temperature.
abstract: Rates of ice mass loss at the calving margins of tidewater glaciers (frontal ablation rates) are a key uncertainty in sea level rise projections. Measurements are difficult because mass lost is replaced by ice flow at variable rates, and frontal ablation incorporates sub-aerial calving, and submarine melt and calving. Here we derive frontal ablation rates for three dynamically contrasting glaciers in Svalbard from an unusually dense series of satellite images. We combine ocean data, ice-front position and terminus velocity to investigate controls on frontal ablation. We find that frontal ablation is not dependent on ice dynamics, nor reduced by glacier surface freeze-up, but varies strongly with sub-surface water temperature. We conclude that calving proceeds by melt undercutting and ice-front collapse, a process that may dominate frontal ablation where submarine melt can outpace ice flow. Our findings illustrate the potential for deriving simple models of tidewater glacier response to oceanographic forcing.
authors.affiliation: Department of Geography, College of Science, Swansea University, SA2 8PP, UK.|Department of Arctic Geophysics, University Centre in Svalbard, Po Box 156, 9171 Longyearbyen, Norway.
authors.forename: Adrian
authors.identifier: http://orcid.org/0000-0002-9618-5905
authors.initials: A
authors.lastname: Luckman
authors.affiliation: Department of Arctic Geology, University Centre in Svalbard, Po Box 156, 9171 Longyearbyen, Norway.|Department of Geography, University of St Andrews, St Andrews, Fife, KY16 9AJ, UK.
authors.forename: Douglas I
authors.initials: DI
authors.lastname: Benn
authors.affiliation: Scottish Association for Marine Science, Oban PA37 1QA, UK.|Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Po Box 6050 Langnes 9037 Tromsø, Norway.
authors.forename: Finlo
authors.initials: F
authors.lastname: Cottier
authors.affiliation: Department of Geography, College of Science, Swansea University, SA2 8PP, UK.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Bevan
authors.affiliation: Department of Arctic Geophysics, University Centre in Svalbard, Po Box 156, 9171 Longyearbyen, Norway.|The Geophysical Institute, University of Postboks 7803 5020 Bergen, Norway.
authors.forename: Frank
authors.initials: F
authors.lastname: Nilsen
authors.affiliation: Scottish Association for Marine Science, Oban PA37 1QA, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Inall