An uncertain future for the Greenland ice sheet
The future melt of the ice sheet is no longer in doubt. However, the extent of the damage this will cause remains to be determined. A great deal of uncertainty exists with regard to climatic scenarios and modeling which makes predictions precarious. The natural variability of the climate makes it impossible to predict atmospheric circulation in summer with any certainty knowing that it is this atmospheric circulation which is the main cause of the current records of melt. In order to model the different possible scenarios, Xavier Fettweis uses a fixed topography of the ice sheet. This does not take into account either the changes in altitude due to the melt of ice, nor ice dynamics, nor discharge from icebergs into the ocean. Knowledge about the ice sheet itself still remains very incomplete and new discoveries constantly change predictions. As proof of the uncertainty surrounding these results, a recent American publication in the journal Nature (Harper et al., 2012) adds another decade to most of the forecasts made by Xavier Fettweis. In their study, the American researchers show the importance of the “percolation zone”. According to them, the meltwater seeps into the empty pores of the snowpack and refreezes in winter without having a direct impact on ocean levels. “In my model, I consider that if the quantity of liquid water present into the snowpack is higher than 7 %, the meltwater flows into the ocean. However, the Americans show that certain zones of the ice sheet have a much higher storage capacity than my model consider. The water which, according to my model, flows into the ocean does not immediately do so”. |
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© 2007 ULi�ge
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