Ice wastage on the Kerguelen Islands (49°S, 69°E) between 1963 and 2006

Abstract

International audienceWe observed the wastage of ice masses on the Kerguelen Islands (Indian Ocean, 49°S, 69°E) using historical information and recent satellite data. Overall, the total ice-covered area on the islands declined from 703 to 552 km2 between 1963 and 2001, a reduction of 21%. The area of Cook ice cap (the main ice body) decreased asymmetrically from 501 to 403 km2. West-flowing glaciers lost 11% of their area while east-flowing glaciers lost 28%. After 1991, the retreat rate accelerated from 1.9 km2/yr (1963-1991) to 3.8 km2/yr (1991-2003). Between 1963 and 2000, the ice volume loss was 25-30 km3, equivalent to an area-average ice thinning rate of 1.4-1.7 m/yr. The glacial retreat took place in the climatic context of a relatively low level of precipitation (compared to the 1950s) and a ~1°C warming that occurred between 1964 and 1982. The acceleration of the ice losses since, at least, the 1990s indicates that the state of the ice bodies on the Kerguelen Islands is still far from balanced. Together with other studies in Patagonia, South Georgia and Heard Island, our analysis is consistent with a pattern of strong and accelerated wastage of ice masses influenced by the Southern Ocean

Changes in the southeast Vatnajökull ice cap, Iceland, between ~ 1890 and 2010

“…a −1 in 1993-1998 (Guðmundsson, 2000). Based on satellite imagery, in situ mass balance measurements and model simulations, the average ELA of southeast Vatnajökull has been estimated to be around 1100-1200 m (Björnsson, 1979;Aðalgeirsdóttir et al, 2005Aðalgeirsdóttir et al, , 2006Björnsson and Pálsson, 2008;Aðalgeirsdóttir et al, 2011). Interannual variability of approximately 200-300 m of the ELA was measured in the time period 1992-2007 (Björnsson and Pálsson, 2008).…”

“…The warming in Iceland since the 1990s has been 3-4 times higher than the average warming of the Northern Hemisphere during the same time interval (Jones et al, 2012;Björnsson et al, 2013), which may explain the high rates of mass loss in the first decade of the 21st century. In situ mass balance measurements of glaciers in Iceland and degree-day mass balance models of selected glaciers indicate that the mass balance is governed by variation in summer ablation (which is strongly correlated with temperature), rather than winter accumulation (Björnsson and Pálsson, 2008 , 2009Pálsson et al, 2012;Björnsson et al, 2013).…”

“…The basal topography of the outlets is known from radio echo sounding measurements (see Björnsson (2009) and Magnússon et al (2012) for details). The glaciers terminate in glacially eroded valleys and have carved into soft glacial and glacio-fluvial sediments.…”

“…The basal topography has been derived from radio echo sounding measurements, carried out in the last two decades (Björnsson andPálsson, 2004, 2008;Björnsson, 2009;Magnússon et al, 2007Magnússon et al, , 2012, and the data base of the Glaciology Group of the Institute of Earth Sciences, University of Iceland = GGIES). We calculate the total ice volume from the bed DEMs and the ice volume changes as a fraction of the total volume.…”

High-resolution dynamical downscaling of re-analysis data over the Kerguelen Islands using the WRF model

“…A better understanding of the current climate of the Kerguelen Islands and its variability is crucial for glacierrelated studies (e.g. Poggi 1977;Berthier et al 2009), to better understand projected future climate change and, given the existence of other islands at similar latitudes in the Southern Hemisphere, to have a general idea of their possible local climate conditions.…”