What kind of glacier covers greenland

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The largest glaciers are continental ice sheets or icecaps, enormous masses greater than 50, square kilometers [12 million acres] of ice found only in Antarctica and Greenland. These sheets contain vast quantities of fresh water. If the Greenland ice sheet melted, it would cause sea levels to rise some 20 feet 6 meters all around the world. If the Antarctic ice sheet melted, sea levels would rise up to about feet 60 meters.

This meltwater lake was created by warm summer temperatures on the surface of the Greenland Ice Sheet. Above this line the ice is still mostly covered with snow from the previous winter.

The position of the equilibrium line changes from year to year as a function of the balance between snow accumulation in the winter, and snow and ice melt during the summer. If there is more winter snow and less summer melting, this favours the advance of the equilibrium line down the glacier and ultimately increases the size of the glacier. Cool summers promote an increase in glacier size, and thus lead to advance of the equilibrium line.

Warm summers promote melting, and retreat of the equilibrium line. Alpine glaciers move because they are heavy, and the force of gravity acts on the ice in the glacier to pull it down the slope of the mountains where they form. The movement of the glacier generates stress in the ice, which is proportional to the slope of the glaciers surface features of the underlying rock surface, and to the depth within the glacier. As shown in Figure Stresses are greater in areas where the ice surface is relatively steep.

Like rock, ice behaves in a brittle fashion under low pressure conditions shallow depths in the glacier , and plastically at higher pressures deeper in the glacier.

Stress also affects how ice deforms; at high stress ice will either break or deform plastically ductile deformation depending on the pressure conditions. Under brittle deformation conditions low pressures, shallow depths in the glacier , stress is released when the ice cracks, so does not build up to high values.

Within the upper 50 — m of ice above the dashed red line, in Figure Under ductile deformation conditions higher pressures deeper in the glacier , stress can accumulate, and the ice will flow plastically in response to that stress. Ice deforms plastically if deeper than about m in the glacier, and in this region stress levels can accumulate to high values kilopascals or greater, Figure When the lower ice of a glacier flows, it moves the upper ice along with it.

It may seem from the stress patterns red numbers and arrows in Figure The lower ice deforms flows and the upper part is carried along and deforms through brittle deformation if subjected to sufficient stress. The upper part of the glacier moves faster than the base of the glacier because there is friction between the base of the glacier and the surface beneath it that slows the movement of the ice at the base. The plastic lower ice of a glacier can flow over irregularities in the rocks under the glacier.

However, the upper rigid ice cannot flow in this way, and because it is being carried along by the lower ice, it tends to crack in locations when the lower ice flows over changes in the topography below the glacier. This leads to formation of crevasses in areas where the rate of flow of the deeper, plastic ice is changing. In the area shown in Figure Circulation relies on the relationship between water with different densities. Cold, saline water from polar regions gradually rises to the surface in the tropics.

Melting ice sheets would increase the amount of warm and freshwater in polar marine ecosystems. This would slow "deep water formation," the development of cold, saline, nutrient-rich water on which entire marine ecosystems depend. This may lead to a reduction in krill , the basis of the Antarctic marine food web. Animals from crustaceans to penguins will face much greater competition for fewer food resources. Greenland's Warming Period In the s, scientists drilled ice cores from the Greenland ice sheet and learned about a short warming period on the continent, called the Medieval Warming.

About 1, years ago, Vikings settled on an island that had green, coastal meadows. They named it Greenland. The Vikings cattle had plenty of green grass to eat and the colony thrived there for years.

There were eventually 3, people in the Viking settlement. Then, Greenland suddenly got colder, during a period called the Little Ice Age. Ice blocked the Vikings ships from sailing. The summers got shorter, producing less vegetation for the dairy cattle during the long, cold winters. Eventually, Vikings left their colony. Martian Ice Caps Ice sheets are sometimes called polar ice caps. The Martian ice caps are made of water and carbon dioxide about 3 kilometers 1. Also called a shooting star or falling star.

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Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. Freshwater is a precious resource on the Earth's surface. It is also home to many diverse fish, plant, and crustacean species.

The habitats that freshwater ecosystems provide consist of lakes, rivers, ponds, wetlands, streams, and springs. Use these classroom resources to help students explore and learn about these places. The cryosphere contains the frozen parts of the planet. They are fewer in number and are constrained to fjords [3].

Over the past few years, there has been an increase in the understanding on the topography beneath the ice sheet from the development of BedMachine v3 [4]. This was created using a series of remote sensing techniques and bathymetric data from the surrounding oceans. This dataset has now allowed the visualisation and quantification of the volume of ice present on the ice sheet, the bed topography, and the thickness of ice.

This understanding has enabled the calculation of the global sea level rise potential of the Greenland Ice Sheet. This is now calculated to be 7. This means that if all the ice in Greenland melted, global sea levels would rise by 7. Ice sheets play an integral role in the global climate system, thus it is important to understand how they have responded in the past. This better prepares us for future changes to both the climate, and global sea level rise [5,6]. During the Quaternary Period last 2.