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The Arctic is an Ecosystem
by Bill Heal
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Snow, Ice And Water
  The three different phases of H2O are the major driving forces that form the landscape and determine the biology and human occupation. Over millenia, snowfall has accumulated and packed down to form the great ice caps and glaciers of the Arctic. The annual layers now form the 'frozen archive' that scientists are exploiting to chart the climate history, especially on the vast mass of the Greenland Icecap. This icecap is up to 3000m deep and virtually the largest freshwater reservoir in the North.
  Icecaps spill over to form the glaciers. These are pushed down slope by the pressure from above, moving by up to 30 metres a year, grinding away the rock surface, picking up debris and transporting it to the glacier tongue where it is deposited as lateral or terminal moraines, or transported away by melt water. The melt water forms the streams and rivers, deep and fast flowing where the terrain is steep, wider and slower on flatter landscapes where the water spreads over the floodplain. Over large areas, water from glaciers and snow melt contributes to the many thousands of ponds and lakes and the wetlands which are such a feature of much of the Arctic.
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But it is the permafrost - another water store - which prevents the water from draining into the deeper layers of soil and rock (see figure 9). So, even with the very low snowfall, less than 300mm in continental areas, the landscape is usually dominated by water. The exception is where stony ground provides drainage, drought conditions inhibit plant growth, and the polar deserts occur. One reason why the snowfall is so low is that cold air carries much less water than warm air. So, near the coast, warm air comes off the sea, it is cooled by the land, especially where it is forced to rise by mountains, and the moisture in clouds is deposited as rain or snow. Thus, whilst coastal areas may be warmer, they have precipitation of up to 3000mm. A consequence of the relationship between temperature and the water holding capacity of air is that climate warming is likely to be linked to increased snow and rain, especially near the coast.
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The Arctic is an Ecosystem, by Bill Heal.
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