Continued evolution of Jakobshavn Isbrae following its rapid speedup

Ian Joughin, Ian M. Howat, Mark Fahnestock, Ben Smith, William Krabill, Richard B. Alley, Harry Stern, Martin Truffer

Research output: Contribution to journalArticle

171 Scopus citations

Abstract

Several new data sets reveal that thinning and speedup of Jakobshavn Isbrae continue, following its recent rapid increase in speed as its floating ice tongue disintegrated. The present speedup rate of ∼5% a-1 over much of the fast-moving region appears to be a diffusive response to the initial much larger speedup near the front. There is strong seasonality in speed over much of the fast-flowing main trunk that shows a good inverse correlation with the seasonally varying length of a short (typically ∼6 km) floating ice tongue. This modulation of speed with ice front position supports the hypothesis that the major speedup was caused by loss of the larger floating ice tongue from 1998 to 2003. Analysis of image time series suggests that the transient winter ice tongue is formed when sea ice bonds glacier ice in the fjord to produce a nearly rigid mass that almost entirely suppresses calving. Major calving only resumes in late winter when much of this ice clears from the fjord. The collapse of the ice tongue in the late 1990s followed almost immediately after a sharp decline in winter sea-ice concentration in Disko Bay. This decline may have extended the length of the calving season for several consecutive years, leading to the ice tongue's collapse.

Original languageEnglish (US)
Article numberF04006
JournalJournal of Geophysical Research: Earth Surface
Volume113
Issue number4
DOIs
StatePublished - Dec 24 2008

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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    Joughin, I., Howat, I. M., Fahnestock, M., Smith, B., Krabill, W., Alley, R. B., Stern, H., & Truffer, M. (2008). Continued evolution of Jakobshavn Isbrae following its rapid speedup. Journal of Geophysical Research: Earth Surface, 113(4), [F04006]. https://doi.org/10.1029/2008JF001023