Greenland is the largest non-continental island in the world. The Greenland Ice Sheet holds about 2.85 million cubic kilometres of ice - 10% of the world’s ice mass. About 81% of the surface is covered by ice and helps to preserve the global energy balance. The ice sheets reflect incoming solar energy and, thus, influence Earth’s temperature.
Greenland is 341,701 sq km large. At the center,
the ice is anything up to 3 km high. The weight of the massive ice cap has depressed the central land area to form a basin lying more than 300 m below sea level. Highest point is Gunnbjørns Fjeld with 3,693 m.
The most productive glacier is Sermeq Kujalleq (Jakobshavn Glacier) near Ilulissat. It is the fastest glacier on Earth and produces about 10% of all the icebergs in Greenland. Several thousands icebergs are produced from Greenland every year. In 2004 NASA scientists used Radar and Landsat images taken from space and found that the Jakobshavn Glacier has doubled his speed from 1997 to 2003.
Warming increases the rate of ice flow off Greenland, because the meltwater penetrates the ice sheet and forms a thin film between the ice and bedrock, which causes the glaciers to slide off the continent faster. If the greenlandic ice sheet melts completely, it would raise the average sea level about 6.5 metres. To compare: Antarctica’s 30 million cubic kilometers ice volume would rise sea level up to 70 meters.
The seasons are causing different melting behaviour of Greenland’s ice caps. With microwave sensors it is possible to analyse the surface of the ice and to differ between dry snow or ice and melting wet snow. In 2002 the melt started unusually early and the coverage was with 686,350 square kilometers 16% higher than the maximum melt area measured in the past 24 years.
The movement of glaciers towards the coast is not a constant slow journey.
The speed of blocks of ice big like buildings can reach up to 10 meters per minute and generate seismic waves. Greenland is not a hotspot of seismic activity due to the constellation of the tectonic plates. Researches analyzed more than 100 seismic events between 1993 and 2005 and found one third happend in warm July and August and the amount of events doubled over the period.
NASA’s GRACE satellites measure directly the mass of the ice cap. According to a new analysis by researchers at the University of Arizona at Austin, the loss of ice from Greenlands southeastern region has sped up between 2002 and 2005.
Approximately 239 cubic kilometers is now lost each year and contribute add 0.56 millimeters annually to sea level, mostly from the eastern shorline. Too much fresh water from Greenland will change the circulation of water in the Atlantic Ocean and may alter the direction of the Norwegian Current which keeps Norway’s harbours ice free.
More facts: Basic facts about Greenland, Greenland in Figures 2005, Volume of Earth’s Polar Ice Caps, Impact of Climate Warming on Polar Ice Sheets Confirmed, Vanishing Ice, Earth Observatory Glacier Hazards From Space
Picture Credits: (1, JSC), (2, bigfoto.com) , (3, Larry Rodrigues), (4, Svante Bj