The cryosphere is the part of the Earth system comprised of frozen water: ice sheets and glaciers, snow, permafrost and sea ice. As the climate warms, the inevitable response of the cryosphere is enhanced melting. This has had, and will continue to have, profound global consequences. The most pressing of these involve:
- thawing permafrost and the potential for enhanced natural emissions of carbon dioxide and methane to the atmosphere;
- shrinking of mountain glaciers and large ice sheets with consequent sea-level rise and impacts on water resources; and
- declining coverage of sea ice and snow, which will affect marine and ground transportation across the Arctic.
In order to make scientifically credible, quantitative projections of these critical changes, we must better understand the underlying processes and improve our capability to represent them in global earth system models.