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letter, about your special case, to:
Greenland Home Rule Authority, Dept. of Fisheries, Hunting and Agriculture, P. O. Box 269, DK-3900
Nuuk, Greenland.
Danish Polar Center
IPY Service Manual for Kangerlussuaq 2008
version 1 June 2008
Compiled and written by Henning Thing (het@fi.dk)
Danish Polar Center Danish Agency for Science, Technology and Innovation
page 27 of 60
Ice Sheet
The Greenland Ice Sheet is a vast body of ice covering roughly 80% of the surface of Greenland. It is the
second largest ice body in the world, after the Antarctic Ice Sheet. The Ice Sheet is almost 2,400 km long in
a north-south direction, and its greatest east-west extend is 1,100 km at latitude of 77° N, near its northern
margin. The mean altitude of the ice is 2,135 metres above sea level. The ice sheet covers 1.71 million km2,
or roughly 80 % of the surface of Greenland. The thickness is generally more than 2 km and over 3 km (i.e.
3,250 m a.s.l.) at its thickest point. It is not the only ice mass of Greenland - isolated glaciers and small ice
caps cover between 76,000 and 100,000 km2 around the periphery. If the entire 2.85 million km3 Ice Sheet
were to melt, it would lead to a global sea level rise of 7.2 m. This would inundate most coastal cities in the
world and remove several small island countries from the face of Earth, since island nations such as Tuvalu
and Maldives have a maximum altitude below or just above this number.
The Ice Sheet is also sometimes referred to under the term Inland Ice , its Danish equivalent Indlandsis or
Ice Cap . However, ice sheet is considered the more correct term as ice cap generally refers to less extensive
ice masses.
The ice of the Ice Sheet is as old as 120,000 years. However, it is generally thought that the Greenland Ice
Sheet formed in the late Pliocene or early Pleistocene by coalescence of ice caps and glaciers. It did not
develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation.
The massive weight of the ice has depressed the central part of Greenland; the bedrock surface is near sea
level over most of the interior of Greenland, but mountains occur around the periphery, confining the sheet
along its margins. If the ice would disappear, Greenland would most probably appear as an archipelago.
The ice surface reaches its greatest altitude on two north-south elongated domes, or ridges. The southern
dome reaches almost 3,000 m at latitudes 63° - 65°N; the northern dome reaches about 3,290 m at about
latitude 72° N. The crests of both domes are displaced east of the centre line of Greenland. The unconfined
ice sheet does not reach the sea along a broad front anywhere in Greenland so that no large ice shelves
occur (the closest ice shelf is at the north coast of Ellesmere Island, Canada). The ice margin just reaches
the sea, however, in a region of irregular topography of Melville Bay southeast of Kap York and Savissivik.
Large outlet glaciers, which are restricted tongues of the ice sheet, move through bordering valleys around
the periphery of Greenland to calve off into the ocean, producing numerous icebergs. The best known of
these outlet glaciers is the Jakobshavn Isbræ, which, at its terminus, flows at speeds of 20 to 22 metres per
day. However, the most productive is Petermann Glacier at the north-western border of the National Park in
North and East Greenland.
On the Ice Sheet, temperatures are generally substantially lower than elsewhere in Greenland. The lowest
mean annual temperatures, about -31°C, occur on the north-central part of the north dome, and mean temperatures
at the crest of the south dome are about -20°C.
The Greenland Ice Sheet has experienced record melting in recent years and is likely to contribute substantially
to sea level rise as well as to possible changes in ocean circulation in the future. In 2006, estimated
monthly changes in the mass of the Ice Sheet suggest that it is melting at a rate of about 239 km3 per year.
Recently, fears have grown that continued global warming will make the Greenland Ice Sheet cross a
threshold where long-term melting of the ice sheet is inevitable. Climate models project that local warming
in Greenland will exceed 3°C during this century. Ice sheet models project that such a warming might initiate
the long-term melting of the ice sheet, eventually leading to a complete melting of the ice sheet. How
fast the melt would eventually occur is a matter of discussion.
The following factors determine the net rate of growth or decline of the Greenland Ice Sheet.
accumulation of snow in the central parts, which adds mass and lowers sea level
Danish Polar Center
IPY Service Manual for Kangerlussuaq 2008
　
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