Fragile Arctic environment plays a major role in global environmental system

While the Arctic suffers special harms from ordinary pollutants, the ordinary conditions of the Arctic play a special role in maintaining the global environment.2' First,the cool water of the marine Arctic plays an important role in global oceanic heat exchange, helping to keep the temperature and salinity of the tropical seas constant;24 second, the Arctic ice reflects solar energy in the form of light, further helping to cool the planet;25 third, although the Arctic is not a significant carbon sink,26 perennial Arctic ice has nevertheless trapped significant amounts of methane and carbon dioxide over the past several hundred years.27 Changes in any of these three processes have potentially major global impacts above and beyond the temperature increases generated by the underlying green- house effect. Decreased Arctic ice will result in a slower hydrological cycle, trapping heat in the tropics and the Arctic, while simultaneously mitigating the temperature effects of climate change on the North Atlantic region.28 Moreover, slower currents are less effective at transporting the evaporated freshwater that would otherwise migrate north from the tropics, creating on the one hand more severe precipitation events in the low latitudes, while on the other hand prevent- ing water vapor from traveling across continental land masses (thus resulting in droughts).2 9 Another result of melting Arctic ice is an overall rise in the global mean sea level.3° Observed increases in sea level due to Arctic melt indicate that decreases in Arctic sea ice and the Greenland ice sheet alone have already contributed a .98 ± .29 millimeter rise to global sea levels.31 Were both the Arctic and Antarctic ice to melt completely-it is difficult to imagine one without the other-the total increase in sea levels would be between seventy-five and ninety meters.32