| Summary: | Snowmelt constitutes an important part of the surface energy and mass balance of the ice sheets of Greenland and Antarctica. In Greenland, the entire ice sheet experiences occasional melt, as indicated by thin, isolated ice lenses in firn cores drilled at the highest part of the ice sheet and supported by regional atmospheric climate models (Ettema et al., 2010). In Antarctica, melt is limited to the coastal areas, but is especially significant in the Antarctic Peninsula, where the melt season may last as long as three months (Tedesco and Monaghan, 2009). On both ice sheets, the largest fraction of the melt energy is invested in the melting of snow rather than ice. The reason is that the Greenland ablation zone is relatively narrow and constitutes less than 10% of the total surface area. In Antarctica, ablation areas form at locations where sublimation (not melt!) locally exceeds snowfall. These so-called blue ice areas constitute less than 1% of the total surface area and as a result, nearly all surface melt in Antarctica is due to snowmelt.
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