Variable glacier response to atmospheric warming, northern Antarctic Peninsula, 1988–2009

B J Davies,N F Glasser,M J Hambrey,J L Smellie,J L Carrivick

doi:10.5194/tc-6-1031-2012

Abstract

Abstract. The northern Antarctic Peninsula has recently exhibited ice-shelf disintegration, glacier recession and acceleration. However, the dynamic response of land-terminating, ice-shelf tributary and tidewater glaciers has not yet been quantified or assessed for variability, and there are sparse data for glacier classification, morphology, area, length or altitude. This paper firstly classifies the area, length, altitude, slope, aspect, geomorphology, type and hypsometry of 194 glaciers on Trinity Peninsula, Vega Island and James Ross Island in 2009 AD. Secondly, this paper documents glacier change 1988–2009. In 2009, the glacierised area was 8140±262 km2. From 1988–2001, 90% of glaciers receded, and from 2001–2009, 79% receded. This equates to an area change of −4.4% for Trinity Peninsula eastern coast glaciers, −0.6% for western coast glaciers, and −35.0% for ice-shelf tributary glaciers from 1988–2001. Tidewater glaciers on the drier, cooler eastern Trinity Peninsula experienced fastest shrinkage from 1988–2001, with limited frontal change after 2001. Glaciers on the western Trinity Peninsula shrank less than those on the east. Land-terminating glaciers on James Ross Island shrank fastest in the period 1988–2001. This east-west difference is largely a result of orographic temperature and precipitation gradients across the Antarctic Peninsula, with warming temperatures affecting the precipitation-starved glaciers on the eastern coast more than on the western coast. Reduced shrinkage on the western Peninsula may be a result of higher snowfall, perhaps in conjunction with the fact that these glaciers are mostly grounded. Rates of area loss on the eastern side of Trinity Peninsula are slowing, which we attribute to the floating ice tongues receding into the fjords and reaching a new dynamic equilibrium. The rapid shrinkage of tidewater glaciers on James Ross Island is likely to continue because of their low elevations and flat profiles. In contrast, the higher and steeper tidewater glaciers on the eastern Antarctic Peninsula will attain more stable frontal positions after low-lying ablation areas are removed, reaching equilibrium more quickly.

Highlights

The relatively small and dynamic northern Antarctic Peninsula Ice Sheet (Vaughan et al, 2003) is located in a region of rapid atmospheric warming, with mean air temperature increasing by 2.5 ◦C from 1950–2000 (Turner et al, 2005)
The −9 ◦C annual isotherm (Morris and Vaughan, 2003; Scambos et al, 2003) has moved southwards, resulting in 28 000 km2 being lost from Antarctic Peninsula ice shelves since 1960 (Cook and Vaughan, 2010)
On Trinity Peninsula, east-coast glaciers shrank at 0.35 % a−1 from 1988–2001, while west-coast glaciers shrank at 0.02 % a−1 and ice-shelf tributary glaciers at 2.69 % a−1

Summary

Introduction

The relatively small and dynamic northern Antarctic Peninsula Ice Sheet (Vaughan et al, 2003) is located in a region of rapid atmospheric warming, with mean air temperature increasing by 2.5 ◦C from 1950–2000 (Turner et al, 2005). The −9 ◦C annual isotherm (the thermal limit of ice shelves determined from observational data) (Morris and Vaughan, 2003; Scambos et al, 2003) has moved southwards, resulting in 28 000 km being lost from Antarctic Peninsula ice shelves since 1960 (Cook and Vaughan, 2010). Ice-shelf tributary glaciers accelerated and thinned following the disintegration of part of the Larsen Ice Shelf (De Angelis and Skvarca, 2003), with up to a six-fold increase in centreline speeds (Scambos et al, 2004). Other tidewater glaciers are accelerating, thinning and shrinking in response to increased atmospheric and sea surface temperatures (Pritchard and Vaughan, 2007). The present-day ice loss for the Antarctic Peninsula is −41.5 Gt yr−1 (Ivins et al , 2011), derived from Gravity Recovery and Climate Experiment (GRACE) measurements and GPS bedrock uplift data.

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Discussion

Conclusion