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"Everywhere the presence of ice is felt. Sea ice is a filter, intervening between air and sea, land and ocean; a lever, amplifying small changes in environmental conditions into large effects." — Stephen J. Pyne, author
They are remote and appear barren, yet the Arctic and Antarctic environments drive the pulse of the planet. Global warming caused by distant industry, unregulated fishing by international fleets and pollution from tainted rivers are three major threats to the health of the polar seas. The affects may appear confined to the Arctic and Antarctic, but their reach actually extends around the globe.
The polar seas play vital roles in maintaining the Earth's climate. As chilled polar seawater sinks, it pushes up warm water, which transfers energy to the atmosphere and liberates nutrients in surface waters. Global warming affects this system by melting sea ice, which contains unsinkable freshwater. It forms a surface barrier that traps nutrients and heat below. The resulting local changes in food sources and climate will eventually affect the entire planet.
 | Striped Notothen. R. Mickens / AMNH |
In the Arctic, toxic chemicals known as PCBs flow into the polar habitat by way of rivers polluted by industrial waste. These contaminants enter the food chain and accumulate in fatty tissue. The result: the PCBs slowly poison predators such as polar bears that depend on high-fat diets.
Many polar species are unnecessary casualties of the fishing industry. Each year, for example, longlines snag thousands of albatrosses, which grab baited hooks before they sink. International regulations and long-term studies have led to some protection measures. Some key fishing fleets use less harmful techniques, such as setting lines at night when most albatrosses aren't searching for food.
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