Australia: The Land Where Time Began

A biography of the Australian continent 

Antarctic Sea Ice Expansion - Important role of Ocean Warming and Increased Ice-Shelf Melt

According to Bintanja et al.¹ climate change is moderated significantly by sea ice changes as a result of its reflectivity and insulating effect. The sea ice surrounding Antarctica, unlike the sea ice in the Arctic, has expanded (Turner & Overland, 2009), attaining a record extent (Cavalieri, Parkinson, Gloersen & Zwally, 1998, updated 2010) in 2010. This expansion has previously been attributed to atmospheric cooling (Thompson & Solomon, 2002) that was induced by dynamical atmospheric changes. In this study Bintanja et al.¹ have shown that it is likely that accelerated basal melting of sea ice contributed significantly to the expansion of sea ice in Antarctica. In particular, the observations they present indicate that the accumulation of meltwater from Antarctica's ice shelves in a cool, fresh surface layer insulated the surface layer from the deeper waters that are warmer and are melting the ice shelves from beneath. Bintanja et al.¹ found that when they simulated these processes in a coupled climate model cool, fresh water from the ice-shelf did indeed lead to expanding sea ice in the austral autumn and winter. Southern Hemisphere atmospheric warming is counteracted by this powerful negative feedback, though the regional sea ice trends are probably governed by changes in atmospheric dynamics (Harangozo, 2006), the analyses carried out by Bintanja et al.¹ indicate that overall the increased melting of ice-shelves dominates the sea ice trend. Bintanja et al.¹ suggest that around Antarctica cool temperatures of the sea surface could offset the increases in snowfall in Antarctica that have been projected, and this has implications for estimates of sea level rise in the future.

Sources & Further reading

1. Bintanja, R., G. J. van Oldenborgh, S. S. Drijfhout, B. Wouters, and C. A. Katsman. "Important Role for Ocean Warming and Increased Ice-Shelf Melt in Antarctic Sea-Ice Expansion." Nature Geosci 6, no. 5 (05//print 2013): 376-79.