About Ice Sheets
Although the Earth has many locations with permanent ice and glaciers, there are only two ice masses that are large enough to be classified as ice sheets: the Greenland Ice Sheet and the Antarctic Ice Sheet. These ice sheets are composed of snow that has fallen, become buried due to additional snowfall over time, and eventually been compressed into very thick ice. The ice sheets are over 1 kilometer thick on average and are the largest reservoir of fresh water on the Earth. They have important effects on the Earth’s climate, and they are also affected by global climate change. The chemistry and physical properties of the snow and ice in Greenland and Antarctica serve as critical archives of past climates.
The Antarctic Ice Sheet started forming about 25 million years ago, and grew to cover most of Antarctica around 4 million years ago. It is over 4.5 km (~ 2.8 miles) deep in its deepest spot. Most (around 90%) of the fresh water on the surface of the earth, and 98% of the Earth's ice, exists as ice in Antarctica; if it all melted, it would raise sea level by approximately 60 meters. The Greenland Ice Sheet started forming around one million years ago, and in the center it is over three kilometers (~ two miles) deep. If the Greenland Ice Sheet melted, it would raise sea level by approximately 6 meters.
Read a comprehensive primer on ice sheets as a downloadable PDF.
For the Press
Quick Links about Ice Sheet Research in IPY for Press.
Information for teachers with educational flyers in many languages, a virtual balloon launch, a live web-conference to the Antarctic, and suggested activities for the classroom.
Launch a Virtual Balloon
Join schools, researchers and interested individuals to mark your participation in Ice Sheet Day on a collaborative map.
IPY Projects Studying Ice Sheets
Over 20 IPY projects studying some aspect of Ice Sheets. This includes expeditions across Antarctica and Greenland, remote sensing, sub-glacial lakes, and studies of how ice sheets calve into the ocean.
Several major traverses are occurring across Antarctica this season as shown in the following map. Here is more information about these expeditions.
You can follow daily updates from the Norwegian-US Scientific Traverse of Antarctica, the US International Trans-Antarctic Scientific Expedition and the Swedish-Japanese Traverse.
Subglacial Lakes and Water Flow Beneath the Ice
Subglacial water and fluxes of water beneath the ice affects ice sheet and ice stream dynamics. The connection between the location of subglacial lakes and ice domes is poorly understood and further study will test the association through observations and models. Important linkages between ice sheets and underlying subglacial environments will be assessed through:
- observations of the surface manifestation of hydrologic processes;
- borehole observations of basal water
- numerical modeling of ice sheet evolution.
For more information, please visit the page on ice sheets and subglacial lakes on the SALE web site.
Links and Resources
Global Outlook for Ice and Snow (United Nations Environment Programme) graphics, images, background information and an entire chapter on Ice Sheets.
CReSIS: Center for Remote Sensing of Ice Sheets
NASA: Impact of Climate Warming on Polar Ice Sheets
Subglacial Antarctic Lake Environments
Antarctic Photo Library (use the search function for Ice Sheets)
Crystal Ball: Scientists Race to Foretell West Antarctica's Unclear Future
Earlier this year, 30 leading polar experts from the U.S. and U.K. met at a workshop to discuss the fate of the West Antarctic Ice Sheet (WAIS). At one time considered to be relatively immune to a warming atmosphere, it’s now clear that the WAIS is thinning and sliding into the sea more rapidly. Uncertainty about the fate of the ice sheet led IPCC authors to largely leave it out of projections of future sea level rise. A new hypothesis developed at the workshop to explain the observations suggests sea level could rise much higher than the IPCC projections.
Larsen B collapse
-Animated GIF of the Larsen B ice shelf collapse
-Animation of Larsen B collapse in Google Earth; see "Breakup of the Larsen B ice shelf"
-NSIDC Lead Scientist Ted Scambos and an international team of scientists are studying ice shelf breakup using Antarctic icebergs as a proxy. The " followed the scientists during their long expedition to Antarctica, and the site is full of incredible photography and descriptions of their adventures.
-Google Earth file showing IceTrek iceberg drift information; see "IceTrek iceberg tracks".
Second print run of our IPY poster is now available. The poster was created with educators and students in mind.
About International Polar Days
In response to journalists and educators wanting an ‘angle’ on the extremely broad International Polar Year, quarterly International Polar Days are being planned that focus on a particular aspect of polar research. These days will include press releases, background information, access to experts, links to images and video, educational and community activities, and connection to researchers in the field.
International Polar Days occur approximately around the solstices and equinoxes to mark the changing solar cycle, experienced in the extreme at the polar regions. In the summer, the polar regions experience 24 hours of sunlight, in winter, the sun is continually below the horizon, and at the equinoxes the sun is above the horizon for 12 hours all over the world. More information can be found here: Solstices, Equinoxes, and the Polar regions
Image credit: SSGT/Lee Harshman, Bill Meurer, National Science Foundation