Recent glacier decline in the Kerguelen Islands (49°S, 69°E) derived from modeling, field observations, and satellite data

Abstract

Cap were compared to data from the early 1970s, providing a 40 year view of the differences in the spatial distribution of surface mass balance (SMB). To obtain additional regional data for the validation of our models, we analyzed MODIS images (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) to determine if our model was capable of reproducing variations in the transient snow line. The PDD model correctly simulated the variations in the snow line, the spatial variations in the SMB, and its trend with elevation. Yet current SMB values diverge from their classic linear representation with elevation, and stake data at high altitudes now display more negative SMB values than expected. By analyzing MODIS albedo, we observed that these values are caused by the disappearance of snow and associated feedback on melt rates. In addition, certain parts of Ampere Glacier could not be reproduced by the surface energy balance model because of overaccumulation due to wind deposition. Finally, the MODIS data, field data, and our models suggest that the acceleration of glacier wastage in Kerguelen is due to reduced net accumulation and an associated rise in the snow line since the 1970s.

Atmospheric drying as the main driver of dramatic glacier wastage in the southern Indian Ocean

“…a −1 less negative glacier-wide mass balance between 2000 and 2009 (assuming extents and elevations from the year 2009). A threshold of 1 °C led to a better agreement with remotely sensed mass balance estimates (Table 1) and with ELA estimates from MODIS images56. Mass balance modeling with the regional circulation model MAR (Modèle Atmosphérique Régional)58 for 2011 also suggests that Tsnow/rain = 1.0 °C is suitable for the PDD at Kerguelen.…”

“…As a consequence, they fail to reproduce the accelerating trend of glacier mass losses. An in depth analysis of precipitation events in models showed that (1) the distributions of precipitation intensity in the models differ significantly from observations, and, (2) even the MRI-ESM1 and MRI-CGCM3 models, which are considered the most comprehensive models in the Kerguelen region, do not reproduce the reduction in precipitation frequency and intensity observed in field data56. Finally, a distinct careful model selection was performed according to ref.…”

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

“…The focus is on the precipitation given its recent decline and major role in the glacier wastage reported at the Cook Ice Cap (Verfaillie et al 2015;Favier et al 2016).…”

“…The Kerguelen Islands feature the Cook Ice Cap, a glacier located at a relatively low altitude and then directly influenced by changes in the oceanic and atmospheric circulations (Vallon 1987;Verfaillie et al 2015). Recently, Favier et al (2016) has shown that the glacier wastage in the Kerguelen Islands during the 2000s was among the most dramatic on Earth.…”

Late Holocene glacier reconstruction reveals retreat behind present limits and two‐stage Little Ice Age on subantarctic South Georgia

“…Geological records of past alpine glacier variations may help close this data gap. Alpine glaciers, found on many Southern Ocean islands, are sensitive to ongoing climate change as demonstrated by their recent rapid retreat (Cook et al, 2005;Gordon et al, 2008;Glasser et al, 2011;Purdie et al, 2014;Verfaillie et al, 2015). This response is driven by changes in temperature and precipitation, which together determine surface mass balance and govern glacial erosion rates (Oerlemans, 2005;Herman et al, 2015).…”