Arctic Ice

Arctic ice is estimated to cover a  land volume of approximately 3.1 million cubic kilometers. If this all melted, it is thought that the sea level would increase a total of 8 meters, world wide. In looking at the Arctic ice total, Greenland holds the largest volume, called the Greenland Ice Sheet. This ice sheet covers more than four times the ice caps and glaciers located in Alaska, Iceland, the Canadian Arctic, northern Scandinavia, Svalbard, Franz Josef Land, Severnaya Zemlya and Novaya Zemlya. Due to location and elevation, more than half of the Greenland Ice Sheet remains frozen year round, unlike smaller glaciers and ice caps, which are more susceptible to climate fluctuations.

The Arctic ice caps and glaciers are distributed about in an irregular pattern.  Because of this, they fall into different climate areas. For example, the glaciers of Iceland and Alaska are in a maritime climate that experiences a fairly narrow temperature range, but they receive high levels of precipitation. If you then take a look at the ice in the Canadian Arctic, you find a continental climate, with a very wide temperature range throughout the year and a very low precipitation rate.

Arctic glaciers come in many forms. Some ice caps form large domes, from which outlet glaciers and lobes of ice flow. In others, large glaciers begin in large ice fields that fill areas between mountain ranges. Still others are individual valley glaciers.

The Arctic is home to many surging glaciers. Surging glaciers can advance several kilometers in only a few short years. This is followed by a long period where the ice builds up again, readying for another surge. Climate changes don't directly affect surges, but if the glacier experiences increased melting, it may take longer between surges.

Smaller glaciers and ice caps are affected more quickly by climate changes than large ice sheets. In fact, the large Greenland Ice Sheet is so slow to react to climate changes that it is still responding to changes made thousands of years ago.

Polar Bear In The Canadian Arctic

With all these differences, it is very hard to come up with a foolproof assessment of the rate of glacier melt and sea level changes. We take the information we have on only a few glaciers, and try to apply it to all the arctic glaciers. This gives us a guesstimate at what we think will happen under different climactic scenarios.

We know that glaciers gain mass from accumulated snowfall, and they lose mass by surface melting, runoff and iceberg calving. We assign a positive value to the mass accumulation zone and a negative value to the ablation zone. In between, we assign an equilibrium line.

It is difficult to estimate how much arctic ice is lost to iceberg calving and how much is lost to melting and runoff. For glaciers that lose more mass by calving, it has been discovered that they can undergo dramatic changes due to climactic change. Not all calving is due to climactic change, however. Sedimentary and erosive processes beneath the glacier seem to play an important role, as well as other internal mechanisms. Calving is therefore unpredictable.