What are polar ice caps?

What exactly is an ice-sheet?

Together, the Greenland and Antarctic Ice Sheets contain sigbificantly more than 99 % of freshwater ice in the world. Credit: NSIDC

an ice-sheet is a mass of glacial land ice extending more than 50, 000 square kilometers (20, 000 square miles). The two ice sheets on the planet today cover nearly all of Greenland and Antarctica. Over the last ice age, ice sheets in addition covered much of North America and Scandinavia.

Together, the Antarctic and Greenland ice sheets contain more than 99 % of this freshwater ice on the planet. The Antarctic ice-sheet expands nearly 14 million square kilometers (5.4 million square kilometers), around the area for the contiguous usa and Mexico blended. The Antarctic ice-sheet contains 30 million cubic kilometers (7.2 million cubic miles) of ice. The Greenland ice-sheet expands about 1.7 million square kilometers (656, 000 square miles), addressing the majority of the area of Greenland, 3 x the dimensions of Tx.

Just how can ice sheets form?

Ice sheets form in areas where snowfall that falls in winter season does not melt entirely on the summertime. Over thousands of years, the layers of snow pile up into dense masses of ice, developing thicker and denser once the fat of brand new snowfall and ice levels compresses the older levels.

Ice sheets are continuously in movement, gradually streaming downhill under their own body weight. Close to the shore, the majority of the ice techniques through reasonably fast-moving outlets labeled as ice channels, glaciers, and ice racks. Providing an ice sheet collects the same size of snowfall because it loses towards ocean, it stays steady.

The Antarctic Ice Sheet covers a location larger than the U.S. and Mexico combined. This photo shows Mt. Erebus rising over the ice-covered continent. Credit: Ted Scambos & Rob Bauer, NSIDC

Why are ice sheets crucial?

Ice sheets have huge degrees of frozen water. If Greenland ice-sheet melted, scientists estimate that sea level would rise about 6 yards (20 feet). In the event that Antarctic ice-sheet melted, sea-level would rise by about 60 meters (200 foot).

In addition, the layers of ice blanketing Greenland and Antarctica contain an original record of Earth's climate history.

Has actually climate change began to affect Earth's ice sheets?

The size of ice within the Greenland ice-sheet features started to decline. From 1979 to 2006, summertime melt on the ice sheet increased by 30 %, achieving a unique record in 2007. At greater elevations, a rise in cold temperatures snow buildup features partly counterbalance the melt. But the decline will continue to outpace buildup because warmer temperatures have actually generated increased melt and quicker glacier motion in the island's edges. To learn more about research on Greenland Ice Sheet, see previous CIRES Director Konrad Steffen's research web site.

Most of Antarctica features however to see dramatic warming. But the Antarctic Peninsula, which juts out into warmer waters north of Antarctica, features warmed 2.5 degrees Celsius (4.5 levels Fahrenheit) since 1950. A sizable part of the West Antarctic Ice Sheet can also be dropping size, probably because of warmer water deeply when you look at the sea nearby the Antarctic shore. In East Antarctica, no clear trend features emerged, though some programs appear to be cooling somewhat. Overall, experts think that Antarctica is beginning to lose ice, but up to now the process has not become as fast or since widespread as with Greenland.

For more information on how changes in the Antarctic ice-sheet could impact sea level, see State regarding the Cryosphere: Ice Sheets and State associated with the Cryosphere: sea-level. To see about an NSIDC scientific study regarding Antarctic ice-sheet, see Antarctic Megadunes.

So what can ice sheets reveal about world's environment record?

Experts extract ice cores from ice sheets and ice hats, studying them to know about previous changes in Earth's environment. Ice sheets are made of layers of snow and ice that obtained over countless years. Those layers have trapped fumes, dust, and liquid molecules that boffins may use to analyze previous climates.

How can I get the full story?

NSIDC Sources
State for the Cryosphere: Ice Sheets. Get a hold of current information about Greenland and Antarctic ice sheets.
State regarding the Cryosphere: Sea Level. Find current information on how ice sheets could impact sea-level.
Antarctic Megadunes Expedition. Read about a report of dune structures in the exact middle of the Antarctic Ice Sheet.

NSIDC Data
NSIDC distributes scientific data units pertaining to ice sheets. See Advanced Data Research to learn more about our information holdings.

Each summertime, researchers go to Swiss Camp regarding the Greenland Ice Sheet to research environment and ice-sheet characteristics. Credit: John Maurer, NSIDC