by Carla White

Created on: December 05, 2009   Last Updated: December 06, 2009

What do glaciers and ice do for us?

1. Food production

Glaciers hold about 75% of the worlds freshwater. Meltwater from glaciers supply major rivers that are used to irrigate the world's food supply. In the U.S., glaciers provide nearly 500 billion gallons of water every summer to Washington state alone (National Snow and Ice Data Center).

The Himalayan and Tibetan Plateau glaciers feed the Ganges, Indus, Yellow and Yangtze rivers during the dry months. As the top two wheat producers in the world, India and China depend on these rivers for year round crop production. Food shortages in these two countries would obviously have massive global ramifications.

A top glaciologist in China, Yao Tandong, has warned that two-thirds of China's glaciers could be gone by 2050. An enlightening discussion on why losing China's and Tibet's glaciers is not just "their problem" appeared in the Washington Post in September 2009.

2. Albedo

Being bright white, ice has a high albedo, reflecting most of the sun's radiation as light, rather than absorbing it as heat. As the world's ice surface shrinks, more surfaces with low albedo - land, water - become exposed, absorbing more heat, thus creating the "ice-albedo feedback" believed to be responsible for much of the apparent rapid warming of the Arctic (Pew Center on Global Climate Change).

While it is not certain what percentage of warming this feedback is responsible for, it is clear that as ice is lost, warming accelerates due to increased absorption of heat by the planet.

3. Sea levels - not just the the stuff of movies

According to the U.S. Geological Survey, "The Earth's climate has warmed about 1C (1.8F) during the last 100 years. As the climate has warmed following the end of a recent cold period known as the "Little Ice Age" in the 19th century, sea levels have been rising about 1 to 2 millimeters per year due to the reduction in volume of ice caps, ice fields, and mountain glaciers in addition to the thermal expansion of ocean water.

If present trends continue, including an increase in global temperatures caused by increased greenhouse-gas emissions, many of the world's mountain glaciers will disappear. For example, at the current rate of melting, all glaciers will be gone from Glacier National Park, Montana, by the middle of the next century.

In Iceland, about 11 percent of the island is covered by glaciers (mostly ice caps). If warming continues, Iceland's glaciers will decrease by 40 percent by 2100 and virtually disappear

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