The Arctic at Risk:
A Circumpolar Atlas of Environmental Concerns

by Stephanie Pfirman, Kathleen Crane, Kim Kane, and Tania Simoncelli

Review Draft: Not for Citation

Environmental Setting

Atmosphere

Deposition from the atmosphere to the land, water, or ice surface occurs as wet or dry deposition, and in some cases by gas exchange across the air-water interface. Wet deposition is material deposited from the atmosphere in rain or snow. Dry deposition is material that deposits from the atmosphere when it is not raining or snowing. Dry deposition may occur not only for particles large enough to settle gravitationally from the atmosphere (Galloway et al., 1982), but also for submicron particles which are circulated near surfaces which they attach to by micrometeorological processes. The latter may be particularly important in the Arctic where wet deposition is low.

Since the 1970's, investigators have noticed elevated concentrations of carbon particles, sulfur dioxide, sulfate, and heavy metals in the winter and spring Arctic atmosphere; these concentrations produce air pollution known as Arctic haze. This haze, which fills the Arctic air mass, covering a region the size of Africa, is attributed to industrial pollution emanating primarily from Eurasia (Barrie and Bottenheim, 1991; Shaw, 1991; Sturges, 1991; Cheng et al., 1993). Many of Eurasia's industrialized sites lie under air pathways that transport local pollution to the central Arctic. Burning coal and oil and industrial processing such as smelting are key sources of the air pollution. Air pollution in the fall, winter, and spring in the Arctic extends in a plume over the North Pole from Eurasia to Svalbard, parts of Greenland, Alaska, and Canada. Much of the air pollution emanating from North America is transported to the northern Atlantic Ocean, Greenland, and Canada.

Arctic haze is at its worst in the winter and spring, because atmospheric circulation then is very different from the circulation in summer. In winter, the Arctic air mass, bounded by the atmospheric polar front, extends far down into Asia and North America, encompassing many industrial regions (Barrie and Hoff, 1984). Air flows northeast from Eurasia into the central Arctic and then out over North America or toward the Aleutians (Raatz, 1991; Barrie et al., 1992). The flow from western Siberia to northern Canada and Alaska, known as the Siberian Express, transports pollutants across the North Pole.

Because of the extremely cold temperatures, there is hardly any precipitation to wash the pollutants from the atmosphere. They stay airborne for weeks to months, and are transported larger distances than in summer. Typical atmospheric transit times across the Arctic are one to two weeks. However, some deposition of pollutants does occur during transport across the pole, following the main atmospheric pathways. In summer, Arctic haze reduces as the winds weaken, precipitation increases, and the Arctic air mass shrinks back to the north of major pollution sources in North America and Eurasia.

Sulfur Dioxide Air Pollution Sulfur dioxide (SO2) is released into the atmosphere from the combustion of sulfur-containing fuels, many industrial processes, and combustion such as incineration. Sulfur dioxide may be inhaled as a gas or converted to atmospheric particles called sulfates. Sulfur dioxide and other air pollutants can directly affect animals and plants (as well as structures) through direct contact. About 60% of the acid comprising acid rain is formed by acidic sulfurous and sulfuric acid, both products of sulfur dioxide (Gardner and Gardner, 1994). The deposition of acid rain, snow, and fog causes environmental degradation by acidifying sensitive lakes, streams, and soils; mobilizing acid-soluble metals; and, in some cases, damaging foliage.

A quantitative assessment of the sources of sulfur to the Arctic region for the period July 1979 to June 1980 estimated that of the anthropogenic sulfur entering the Arctic, about 25% was from western Europe, 27% from eastern Europe, 42% from the FSU, and 4% from North America (Barrie and Bottenheim, 1991). The low value for North America is due to the fact that emissions are swept eastward over the North Atlantic, where removal from the atmosphere in wet deposition is high (Barrie and Bottenheim, 1991). Since the 1950's, winter acidity of the Arctic snowpack has increased due to increased air pollution (Barrie et al., 1985; Lockhart et al., 1992). However, in the past few years, pollution of the Arctic atmosphere has decreased, at least in part in response to decreased industrial activity in Russia and eastern Europe.

Ozone Depletion

The ozone layer, located high up in the stratosphere (between 15 and 50 km above the earth's surface), protects the earth from the sun's ultraviolet rays. This stratospheric layer is now being depleted in the Antarctic, forming the "ozone hole," due to the action of chlorofluorocarbons (CFCs) and other halocarbons. We use halocarbons for refrigerants, such as coolants in air conditioners and refrigerators, and in other industrial activities. Chlorine and bromine from halocarbons combined with icy clouds formed at low temperatures (less than -85deg.C) facilitate chemical interactions that destroy ozone. Although ozone loss is most dramatic over the South Pole, ozone depletion has also occurred in the winter in the Arctic. Warmer temperatures in the Arctic stratosphere have kept the depletion from progressing as far as in the Antarctic. In the Antarctic, total ozone decreases by over 60% in springtime, followed by recover before summer begins.

Exposure to additional ultraviolet rays could lead to increased incidence of skin cancer, and eye cataracts, and losses in ocean productivity in Arctic waters. However, ozone depletion is expected to peak around year 2000 due to reductions in halocarbon production mandates under the Montreal Protocol.

Climate

Winter in the Arctic is characterized by long, cold periods with frequent storms. The coldest regions are in Alaska, Siberia, eastern Canada, and Greenland. Snowfall decreases toward the north.

Summertime temperatures are more uniform, ranging from about 10deg.C along the southern margin to about 0deg.C over sea and glacier ice. During the summer, extensive fogs and low clouds make the Arctic one of the cloudiest regions of the world (Encyclopedia Britannica, 1990).

While the air over the North Atlantic Ocean has cooled, much of the Arctic land surface has warmed significantly over the past several decades (Chapman and Walsh, 1992). Continued warming is expected in these regions due to the enhanced greenhouse effect, which causes global warming. Some computer models predict extreme warming over most of the circumpolar land area, with the exception of the North Atlantic, which is predicted to not change as much. If warming proceeds as predicted, sea ice could thin and become less extensive on the shelves, with profound effects on biologic activity and planetary heat balances. Several species of marine mammals are dependent on ice for their survival. For example, ringed seals use the ice to breed. Polar bears need the ice to move to regions rich in seals. Whales such as bowheads, narwhals, and belugas shelter in heavy pack ice for a substantial part of the year.

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