Mar 31, 2013

Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion

by
R. Bintanja, G. J. van Oldenborgh, S. S. Drijfhout, B. Wouters, C. A. Katsman
,
Nature Geoscience
  • States changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature
  • States that in contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded, with record extent in 2010
  • States this ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling
  • Shows that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion
  • Presents observations indicating that melt water from Antarctica’s ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves
  • Finds that cool and fresh surface water from ice-shelf melt indeed leads to expanding sea ice in austral autumn and winter
  • Finds this powerful negative feedback counteracts Southern Hemispheric atmospheric warming
  • States that although changes in atmospheric dynamics most likely govern regional sea-ice trends, the analysis indicates that the overall sea-ice trend is dominated by increased ice-shelf melt
  • Suggests that cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise