Antarctic Ice Sheet

The Antarctic ice sheet is the largest single mass of ice on Earth, covering about 14 million square kilometers and holding around 90 percent of the planet's ice. Its ice is on average about 2 kilometers thick and reaches nearly 5 kilometers in places, and it contains enough water to raise sea level by roughly 58 meters.

The Transantarctic Mountains divide the continent into the East Antarctic ice sheet, which is much larger and rests mostly on bedrock above sea level, and the West Antarctic ice sheet, much of which rests on bedrock below sea level. Floating ice shelves, such as the Ross and Ronne-Filchner shelves, fringe the coast and hold back the ice behind them. Where ice sits on ground that slopes down toward the interior, warm water reaching the grounding line can drive retreat that is hard to stop.

Ice cores from sites such as Vostok and EPICA Dome C reach back about 800,000 years and show that carbon dioxide and temperature moved together through the ice ages. In recent decades the West Antarctic ice sheet and the Antarctic Peninsula have been losing mass, notably in the Thwaites and Pine Island glacier basins, while East Antarctica has been close to balance or slightly gaining in places because of heavier snowfall.

Cold, salty water formed around Antarctica sinks to feed Antarctic Bottom Water, a major driver of the deep ocean circulation. Its bright surface reflects sunlight, shaping Earth's energy budget, and the continent's ice and surrounding sea ice are monitored closely as part of glaciology. Together with Greenland, it determines the long-term rise in sea level.