SEASONAL CHANGES IN snow and ice cover on the Earth's surface result largely from the Earth's position relative to the sun. However, because ice systems also respond to climate on longer timescales, they are considered good indicators of the Earth's climate as a whole. In addition to being good climatic indicators, glaciers and ice sheets influence the Earth's climate in two important ways. The first is their potential impact on sea-level rise and global water resources under declining ice regimes. Glaciers and ice sheets account for two-thirds of the Earth's freshwater and would contribute approximately 229 ft. (70 m.) to sea-level rise if they were to melt completely.

The majority of this ice is located in the Earth's polar regions, largely in the Greenland and Antarctic ...