The cryosphere - past, present, and future: a review of the frozen water resources of the world

摘要

The paper addresses the frozen water resources of the world based on a literature review. The components of the global cryosphere are first summarized. Then the accessible frozen water resources of the world are examined-seasonal snow cover and its regional variations-freshwater ice, and mountain glaciers. Mountains play a dominant role in discharge by virtue of their seasonal snow cover. Current trends in seasonal snow cover and mountain glacier ice volume are discussed. Earlier snowmelt has led to advances in the timing of peak runoff. Due to warming trends, the proportion of precipitation falling as snow is decreasing at lower elevations. Model predictions for this century indicate that the greatest changes will occur in snow-dominated basins in mid- to high-latitudes. Future water resources from glaciers, associated with glacier retreat, are projected to lead to increased river runoff in the near term and then significant reductions with a shift in the timing of peak flow. The long-term changes associated with ice sheet mass loss will lead to sea level rise of between 0.9 and 1.6 m by 2100.