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The Arctic is warming at more than twice the rate of the earth as a whole. Since 1979, Arctic warming has reduced summer sea ice by more than 40 percent, and many climate models now predict that all sea ice will disappear by 2030 or sooner. To put this in perspective, the amount of sea ice lost from 1980 to 2007 would cover half of the European Union.

Loss of sea ice increases Arctic warming as the increasing exposure of dark surfaces absorbs more heat. The related warming of Greenland poses a global climate "tipping point" - that point where one change (e.g. an increase in temperature) could launch a series of cascading events that drastically alter the earth's ecological balance.

The tipping point could include setting the stage for irreversible melting of a large part of the Greenland ice sheet in coming decades and centuries. In fact, according to recent satellite data, Greenland itself is already starting to lose a significant amount of ice, making a contribution to global sea-level rise every year. The complete loss of Greenland would raise world sea levels by seven meters, inundating the world's densely populated coastal areas.

The tipping point could also trigger a rapid and uncontrollable release of carbon and methane stored in Arctic permafrost, enormously increasing the concentration of CO2 and methane in the atmosphere and therefore adding to the warming of the planet. At present, discussions of steps to slow this warming have focused mainly on reducing CO2 emissions. For the long-term stability of the Arctic as well as the rest of the globe, CO2 reductions must take place as soon as possible. Once emitted into the atmosphere, CO2 remains for centuries. We thus already have a large "bank" of CO2 in the atmosphere that ensures continued warming, and melting, in the Arctic for many decades to come.

So have we already lost the Arctic? Many climate experts concede that its survival - with its unique flora, fauna and cultures - has begun to seem unlikely.

There is reason still for hope, however. CO2 is not the only contributor to Arctic warming. Research shows that several short-term pollutants - specifically black carbon, tropospheric ozone (near the earth's surface) and methane - collectively have nearly the same temperature impact on the Arctic as CO2.

Black carbon or "soot" particles emitted from diesel engines, agricultural burning, and factories cause warming in the Arctic by turning ice and snow darker so that it melts more quickly. Ozone smog originating from cars, trucks, and power plants traps heat in the Arctic, especially in winter and early spring. Methane from landfills, coal mines and agriculture, has an indirect effect on the Arctic by contributing to the formation of ground ozone. Methane is well understood as a greenhouse gas that is mixed in the global atmosphere and directly contributes to atmospheric warming. Methane (and carbon dioxide) add to the warming of the Arctic because heat is naturally transported pole ward.

Why is there hope? Because these three pollutants have relatively short life-times (days, months, and a decade, respectively). A focused effort to reduce them in the next decade, along with CO2, could deliver a swift Arctic-climate response, potentially enough to save the region closer to its current form than the outcome foreseeable with present trends - provided we act quickly.

There is also good news in the fact that controlling these emissions is relatively straightforward, mostly involving "end of the pipe" technologies that could be rapidly implemented on a wider scale than at present. For black carbon especially, the most potent sources lie in the northern latitudes, generally speaking above the latitude of 40 degrees north (i.e., the area north of an imaginary line running roughly from San Francisco through Chicago to Rome). The prevailing winds then deposit the soot further north. This means that much of the remedial action lies with the nations of North America and Europe.

Governments should control these pollutants because they also damage human health. Europe for example already does so under the NEC (National Emissions Controls) process; this process is currently under revision, and NEC reductions could be accelerated as part of a concerted Arctic climate strategy.

The stark reality: curbing short-lived climate-forcing agents is a promising strategy for slowing Arctic warming before it is too late. Will we Arctic nations and Europe act in time?

Rafe Pomerance is President of Clean Air Cool Planet and former U.S. Deputy Assistant Secretary of State for Environment and Development.

Armond Cohen is President of the Clean Air Task Force.