Antarctic Peninsula environmental change
Numerous recent papers have documented increasing atmospheric[1-3] and oceanic temperatures[4, 5] across the Antarctic Peninsula and Southern Ocean. Atmospheric air temperatures rose by 2.5°C in the northern Antarctic Peninsula from 1950 to 2000. This is far greater than the global average of 0.6°C per century. This warming may have been ongoing since the 1930s. This environmental change has been linked to an intensification of circumpolar westerlies and the Antarctic Circumpolar Current[8, 9]. A strengthening of the circumpolar vortex results in asynchronous change, with cooling over East Antarctica and warming over West Antarctica. Decreased sea ice in the Bellingshausen Sea enhances warming over the western Peninsula and Weddell Sea. At the same time, there has been less snow falling over the south-western Antarctic Peninsula[10, 11].
Antarctic Peninsula glacier change
This climate change has led to a rapid glaciological response, with 87% of glaciers around the Antarctic Peninsula now receding, and many glaciers thinning and accelerating. The most dramatic response has been the collapse of several ice shelves, with 28,000 km2 being lost since 1960. This has resulted in glacier acceleration, thinning and recession[15, 16]. This is covered in more detail under Ice Shelves. Larsen-A and the Prince Gustav Ice Shelf on northern Trinity Peninsula were the first ice shelves to collapse in 1995, with a combined area of 2030 km2.
James Ross Island
New mapping of the glaciers of James Ross Island and Trinity Peninsula between 1988 and 2009 has shown a complex glacier response to environmental change. In 2009, this area had 194 glaciers covering 8140 km2. Trinity Peninsula was drained by outlet and valley glaciers.
The collapse of Prince Gustav Ice Shelf had a significant impact on its tributary glaciers. Following collapse, tributary glaciers thinned, accelerated and receded. Between 2001 and 2009, Röhss Glacier, a tributary from James Ross Island, thinned and centre flow line speeds increased (from 0.1 m per day in 2005-2006 to 0.9 m per day 2008-2009).
The role of glacial structures
Glaciological structures may be an important control in ice-shelf collapse. The structural discontinuities indicate that Prince Gustav Ice Shelf was not a cohesive structure, with weaknesses in the suture zones. Structural discontinuities and rift zones visible in a 1998 Landsat image suggest that disintegration began at least 7 years prior to collapse. During this period, rates of sediment accumulation on the sea floor beneath the ice shelf increased between 1985 and 1993, as a result of debris release following pond and lake drainage.
Across the wider region, glacier response to climate change and ice-shelf collapse was varied. Across Trinity Peninsula, on the eastern coast, glaciers shrank at -0.35% per annum from 1988-2001. West-coast glaciers shrank at -0.2% per annum. Ice-shelf tributary glaciers shrank at -2.69% per annum. From 2001-2009, east-coast tidewater glaciers shrank at -0.21% per annum, west-coast glaciers at -0.03% per annum, and former ice-shelf tributary glaciers at -0.96% per annum. From 1988-2001, 90% of the glaciers in the region shrank, and 79% shrank from 2001-2009, although rates of recession varied strongly spatially.
This research shows that ice-shelf tributary glaciers shrank fastest overall, and particularly rapidly from 1988-2001. However, among the remaining tidewater glaciers, rates of shrinkage are highly variable. Variable rates of shrinkage are probably controlled by calving processes and non-linear responses to climate change. However, the large differences between the east and west Trinity Peninsula are likely to be a result of strong atmospheric temperature and precipitation gradients; the more stable western Trinity Peninsula is warmer, but receives far more snow[3, 11, 21].
For glaciers feeding the former ice shelf, rates of shrinkage were highest immediately following ice-shelf collapse. This is because ice-shelf removal destabilises tributary glaciers, because ice shelves reduce longitudinal stress and limit glacier motion upstream of the ice shelf[13, 22]. By 2001, these glaciers had begun to stabilise and find a new dynamic equilibrium, and rates of recession began to reduce once they were within their narrow fjords. Fjord geometry is a major control on tidewater glacier dynamics, with shrinkage slowing as a result of enhanced backstress and pinning against fjord sides.
Glacier recession around the northern Antarctic Peninsula therefore had three distinct phases: 1988-1995: stable ice-shelf period (possibly with thinning and some early ice-shelf melting); 1995-2001: the period of ice-shelf disintegration and rapid readjustment of ice-shelf tributary glaciers to new boundary conditions; and 2001-2009: shrinkage of all glaciers in response to increased atmospheric and oceanic temperatures.
- Antarctic Peninsula Ice Sheet
- Ice shelves
- Antarctic Peninsula photographs
- Antarctic Peninsula Ice Sheet evolution
- Glaciers and climate change
Please see the original papers and cite as:
Davies, B.J., Carrivick, J.L., Glasser, N.F., Hambrey, M.J. and Smellie, J.L., 2012. Variable glacier response to atmospheric warming, northern Antarctic Peninsula, 1988–2009. The Cryosphere, 6: 1031-1048. (download PDF)
Glasser, N.F., Scambos, T.A., Bohlander, J.A., Truffer, M., Pettit, E.C. and Davies, B.J., 2011. From ice-shelf tributary to tidewater glacier: continued rapid glacier recession, acceleration and thinning of Röhss Glacier following the 1995 collapse of the Prince Gustav Ice Shelf on the Antarctic Peninsula. Journal of Glaciology, 57(203): 397-406.
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