The Antarctic Peninsula is warming very rapidly, about six times the global average[1-3]. There has been a 95% increase in positive degree day sums since 1948[4]. Glaciers in the region are accelerating, in response to frontal thinning and recession[5]. In addition, ice shelves are collapsing[6], glacier fronts are retreating[7]. The causes for much of these changes has often been attributed to ocean forcing, with warm ocean waters melting these glaciers from below[8-11]. However, while ocean forcing may dominate further south, such as at Pine Island Glacier, a few recent papers have highlighted the importance of surface processes and surface melt induced by warmer surface air temperatures and longer melt seasons, specifically on the Antarctic Peninsula.
Davies et al (2014) used glacier modelling to investigate glacier-climate relationships on James Ross Island. They found that the glacier was very sensitive to just small changes in surface air temperature, and was vulnerable to rapid recession. They also found that increased accumulation was not able to halt this recession[12].
This work supports earlier work led by Nerilie Abram, who used ice core data to reconstruct melt on the Mount Haddington Ice Cap on James Ross Island. The James Ross Island ice core showed that summer melt layers had increased dramatically over the last few decades, following a sustained period of temperature increases[13]. This rapid increase in surface melt contributed to the collapse of Prince Gustav Ice Shelf in 1995 AD, when meltwater ponds formed on the surface, resulting in hydrofracture and sustained, rapid iceberg calving[14].
A third recent study, just published in Science by Rebesco and colleagues, used marine geology to investigate grounding line stability in the Larsen B embayment[15]. They found that the grounding line in the Larsen B Embayment was actually 12,000 years old – suggesting that the grounding line was well within the fjord before the 2002 ice-shelf collapse. This suggests that ice-shelf collapse was not a response to grounding line instability, but was rather caused by strong surface warming.
These recent studies highlight the importance of surface mass balance processes in controlling glacier recession and ice-shelf collapse in the northern Antarctic Peninsula. Strong atmospheric warming puts these glaciers at considerable risk, which may be exacerbated by continued regional changes to ocean circulation.
The papers
Davies et al., 2014. Modelled glacier response to centennial temperature and precipitation trends on the Antarctic Peninsula. Nature Climate Change.
Abram et al., 2013. Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century. Nature Geoscience 6, 404-411
Rebesco et al., 2014. Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica. Science 345 (6202), 1354-1358
- Morris, E.M. and A.P.M. Vaughan, Spatial and temporal variation of surface temperature on the Antarctic Peninsula and the limit of viability of ice shelves, in Antarctic Peninsula climate variability: historical and palaeoenvironmental perspectives, E.W. Domack, et al., Editors. 2003, American Geophysical Union, Antarctic Research Series, Volume 79: Washington, D.C. p. 61-68.
- Vaughan, D.G., et al., Devil in the detail. Science, 2001. 293(5536): p. 1777-1779.
- Turner, J., et al., Antarctic climate change during the last 50 years. International Journal of Climatology, 2005. 25: p. 279-294.
- Barrand, N.E., et al., Trends in Antarctic Peninsula surface melting conditions from observations and regional climate modeling. Journal of Geophysical Research: Earth Surface, 2013. 118(1): p. 315-330.
- Pritchard, H.D. and D.G. Vaughan, Widespread acceleration of tidewater glaciers on the Antarctic Peninsula. Journal of Geophysical Research-Earth Surface, 2007. 112(F3): p. F03S29, 1-10.
- Cook, A.J. and D.G. Vaughan, Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years. The Cryosphere, 2010. 4(1): p. 77-98.
- Cook, A.J., et al., Retreating glacier fronts on the Antarctic Peninsula over the past half-century. Science, 2005. 308(5721): p. 541-544.
- Pritchard, H.D., et al., Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature, 2012. 484(7395): p. 502-505.
- Hellmer, H.H., et al., Twenty-first-century warming of a large Antarctic ice-shelf cavity by a redirected coastal current. Nature, 2012. 485(7397): p. 225-228.
- Jacobs, S.S., et al., Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nature Geoscience, 2011. 4(8): p. 519-523.
- Jenkins, A., et al., Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat. Nature Geoscience, 2010. 3(7): p. 468-472.
- Davies, B.J., et al., Modelled glacier response to centennial temperature and precipitation trends on the Antarctic Peninsula. Nature Clim. Change, 2014. advance online publication.
- Abram, N.J., et al., Acceleration of snow melt in an Antarctic Peninsula ice core during the Twentieth Century. Nature Geosci, 2013. 6: p. 404-411.
- Glasser, N.F., et al., 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, 2011. 57(203): p. 397-406.
- Rebesco, M., et al., Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica. Science, 2014. 345(6202): p. 1354-1358.
