icecap and icebergs

The Ice Cap and the first Icebergs

FACTS

Satellite image of Greenland. You clearly see the ice cap covering almost entire Greenland. Only in summer the coastal areas are free of snow.
Far left you can see Baffin Island.
(from: NASA)

The Greenland icecap contains 1/12th of the total global ice-mass. The total ice-mass on earth is 30 million. cubic km; Antarctica has 27 million.cubic km; Greenland 2.5 million. cubic km.
The mean height of the Greenland icecap: 2135 meters; 65% of the area lies above 2000 meters; That is why Greenland deserves the name most extreme highland in the world.
Lowest recorded temperature: -70° C (1953 station Northice). Mean annual temperature: -20°C and -30°C: So the Greenland icecap is without any doubt the coldest place in the northern hemisphere, colder than the north pole. Although lowest temperature ever recorded in the northern hemisphere is -78° C Oimekon, Siberia. The world record was gained in Antarctica Station Vostok -88° C.

Because the snow-surface reflects most of the sunlight, the temperature is lowest near the snow and increases in upper air levels to 2 km. This is an exceptional situation because usually temperature decreases in higher air levels. The dome structure of the icecap causes cold air to flow constantly to lower areas at the edges. So, crossing the icecap you will always experience head wind until the top of the icecap and then backwind.

Above the seas around Greenland the air is less cold and thus creates a substantial difference in temperature and air-pressure between the coast and the inland. This can cause terrible storms: the feared Piteraqs.

The Formation of the Greenland ice cap

icecap scheme

1. 50-10 million years ago. We see an ice-free highland, bordered by coast- mountains. The climate is warm

2. Three mil. years ago. The climate gets cooler. The first glaciers appear in the coast-mountains.

3. Two mil. years ago. The snowfields in the centre highland do not melt anymore in summer. A land glacier comes up.

4. This land glacier melts together with the glaciers in the coast mountains to make the icecap which also covers the coastal areas. By the increasing weight of the icemasses, the land beneath is pressed down.

5. After the last ice-age the icecap melts off a little bit, and the coast becomes icefree.

The Formation of the Greenland ice cap
	1. 50-10 million years ago. We see an ice-free highland, bordered by coast- mountains. The climate is warm
2. Three mil. years ago. The climate gets cooler. The first glaciers appear in the coast-mountains.
3. Two mil. years ago. The snowfields in the centre highland do not melt anymore in summer. A land glacier comes up.
4. This land glacier melts together with the glaciers in the coast mountains to make the icecap which also covers the coastal areas. By the increasing weight of the icemasses, the land beneath is pressed down.
5. After the last ice-age the icecap melts off a little bit, and the coast becomes icefree.

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At present the maximum thickness of the icecap is 3200 to 3400 meters. It contains around 2.5 million cubic km of ice. If the icecap should melt, the sea surface worldwide would rise with 6 to 7 meters! The glaciertongues come down from the inland-icecap and reach the sea. On the westcoast is the worldfamous Ilulissat (or; Jakobshavn) icefjord. .Here the glacier moves into the sea with an average speed of 20 to 30 meters a day (= 7 to 11 km. a year) Every day millions of tons of ice calves from the glacier in the form of icebergs. Seeing these icebergs was one of the most fascinating experiences I've ever met. Click on diagram on your right for more details about the formation of this impressive glacier

Is the icecap growing?

Yes, around 20 to 30 cm. a year. This is a sign for the global warming-up theory and the greenhouse-effect. When temperatures rise, more oceanwater evaporates and causes more precipitation. So in the first phase the amount of precipitation is higher than what the inlandice loses with melting and calving icebergs. But in the end the meltingproces will dominate. (The normal situation is a balance; losses and gains compensate each other). The melting of the ice and rising of the sealevel can have disastrous effects for the earth, especially for the densely populated areas!

Press here for more, detailed information about the icecore as a climate archive

If you click on the image above, you will find more information about the icebergs tracks click on the image for details about the seasonal ice growth around the Greenland seas
Click HERE for current ice concentration in the Arctic:

Hear the sound of cracking and thundering ice in Real Audio

ANATOMY OF AN ICEBERG
Usually 1/5th of an iceberg is above the waterline. That part consists of snow, which is not very compact. The ice in the cold core is very compact (and thus relatively heavy) and keeps 4/5th of the iceberg under water. The temperature in the core is constant: between -15 and -20 degr. Centigrade. An iceberg that has tumbled over several times, has lost is light snow layers and so the iceberg gets relatively heavier then before (with the snow) and because of the greater compactness, only 1/10th rises above the surface.

For detailed information about the destructive forces of icebergs press button
How can icebergs float?
Here is the answer

Finally we reached the inlandicecap. From afar we heard the banging of ice, because of the constant movement and temperaturedifferences of the glacier. On this pictures we are about 5 km. from the inland ice. It is a 20 km (rather easy) walk from the airport Søndre Strømfjord (Kangerlussuaq).

We celebrated the arrival with whiskey and inlandicecubes, which contains bubbles due to its age (some 10.000 years old). With a little luck you can see the walls breaking into giant pieces with tremendous noise.

A view over the Ilulissat-icefjord. Completely filled with icebergs, broken off from the icecap. Because of an undepth at the end of the fjord, the icebergs can not go over this threshold and must wait untill it is pressed over it. It is very difficult to estimate sizes, there is nothing to compare with. But the highest tops reaches at least 120 m. (so, 800 meters are below the surface!)

Myself looking over the icefjord

An iceberg floating north in the midnightsun

	Iceberg in the midnight sun (click to enlarge 12k)
	This is a "fresh calved" iceberg, considering the deep crevasses in the ice; after a while the iceberg will tumble over, because of the fact that the berg gets top heavy by rubbing water and waves. Exactly this unexpected tumbling-over makes icebergs so dangerous to ships

	Looking downwards into an iceberg (click to enlarge 18k)
	After sometime real lakes can be seen inside an iceberg. This image makes clear how crystal clear the water is and why icebergs look so blue. It's said the bluer the ice the "younger" it is. Although that is not always true


If you click on the image above, you will find more information about the icebergs tracks		click on the image for details about the seasonal ice growth around the Greenland seas Click HERE for current ice concentration in the Arctic: