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U.S. scientists to study Arctic smog

Key question: Is air pollution from lower latitudes causing the region's recent warming?

By Peter N. SpottsStaff writer of The Christian Science Monitor / April 16, 2008

Despite its pristine image, the Arctic has a serious smog and soot problem.

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Scientists from three federal agencies are now engaged in the most ambitious effort yet to measure airborne pollutants in the Arctic and gauge their effect on the region's climate.

For three weeks this month, and another three weeks this summer, they are marshaling satellites, instrument-laden aircraft, oceanographic ships, and ground stations to study the gases, aerosols, and black-carbon soot that accumulate in the region from human activities and wildfires.

By some accounts, these pollutants – especially soot from inefficiently burned fossil fuels and from burning biomass – could be responsible for a significant portion of the region's recent warming.

That warming has outpaced projections from climate models. And it's led to a dramatic loss of summer sea ice in the Arctic Ocean. If current trends continue, some researchers say, the Arctic Ocean could be ice-free in the summer within the next 10 years – with ripple effects that would touch climate and weather patterns at lower latitudes.

Scientists have long observed that atmospheric circulations have carried pollutants into the skies above the Arctic, turning them into something of a dumpster for the Northern Hemisphere's air pollution. More recently, the vast northern forests in Russia, Canada, and Alaska have seen rising numbers of wildfires, adding their emissions to the mix.

"There is an urgent need to better understand changes going on in Arctic pollution" and its effects on the region's climate, says Harvard University's Daniel Jacob, who specializes in atmospheric chemistry and is chief scientist for ARCTAS, the National Aeronautics and Space Administration's contribution to the effort.

The two-phase study is part of a broader international effort – associated with the International Polar Year – to understand the sources and effects of airborne pollutants reaching the region.

The ambitious project follows on the heels of major field efforts in the late 1990s and last year looking at similar issues in the Indian Ocean and across the northern Pacific Ocean. Taken together they should provide a more detailed global picture of the impact air pollution can have on weather and climate and how those effects change with latitude, according to Veerabhadran Ramanathan, director of the Center for Clouds, Chemistry, and Climate at the Scripps Institution of Oceanography in La Jolla, Calif. He played a leading role in these earlier research projects.