- 2015 Elsevier Ltd. All rights reserved. Glaciers are distinct features of Earth's climate system and, combined with sea ice, form the cryosphere. Glaciers currently exist around the globe from the polar regions to tropical high altitudes. Although composed of ice, they are very dynamic and play an extremely important role in shaping the land surface in alpine regions as well as regulating regional climate. Glaciers also play a fundamental role in providing freshwater resources to a significant fraction of the world's population. Monitoring of glaciers is an important component in the effort to determine the effects and ramifications of climate change.