Estimation of the Sea Level Rise by 2100 Resulting from Changes in the Surface Mass Balance of the Greenland Ice Sheet

Abstract

The Surface Mass Balance (SMB) can be seen, in first approximation, as the water mass gained by the winter snowfall accumulation minus the mass lost by the meltwater run-off in summer. The mass gain from rainfall as well as the mass loss from erosion from the net water fluxes (the sum of the evaporation, sublimation, deposition and condensation) and from the wind (blowing snow) are negligible in the SMB equation of the Greenland Ice Sheet (GrIS) compared to the snowfall and the melt (Box et al., 2004). The ice sheet mass balance takes also into account the mass loss from iceberg calving. Consequences of a warmer climate on the Greenland ice sheet SMB will be a thickening inland, due to increased solid precipitation, and a thinning at the Greenland ice sheet periphery, due to an increasing surface melt. A climatic warming increases the snow and ice melting in summer but it enhances also evaporation above the ocean. This leads to higher moisture transport inland and, consequently, higher precipitation. The response of the iceberg calving to the climate change could be an acceleration of the glacier flow (Nick et al., 2009; Zwally et al., 2002) but these projections are very uncertain (Sundal et al., 2011) and a lot of developments are still needed in the glaciology models for improving our knowledge and modelling of the Greenland ice sheet dynamics. That is why we will focus our study only on the SMB of the Greenland ice sheet. The IPCC (Intergovernmental Panel on Climate Change) projects, in response to global warming induced by human activities, that the run-off increase will exceed the precipitation increase and therefore that the currently observed surface melting of the Greenland ice sheet (Fettweis et al., 2011b; Tedesco et al., 2011; Van den Broeke et al., 2009) will continue and intensify during the next decades (IPCC, 2007). An increasing freshwater flux from the Greenland ice sheet melting could perturb the thermohaline circulation (by reducing the density contrast driving this last one) in the North Atlantic including the drift which tempers the European climate. In addition, an enduring Greenland ice sheet melting, combined with the thermal expansion of the oceans and the melt of continental glaciers, will raise the sea level with well-known consequences for countries such as the Netherlands, Bangladesh,... The contribution of the Greenland ice sheet SMB decrease to the sea level rise is currently evaluated to be 5-10 cm by 2100 (Gregory and Huybrechts, 2006; Fettweis et al., Estimation of the Sea Level Rise by 2100 Resulting from Changes in the Surface Mass Balance of the Greenland Ice Sheet 25