Easily 40 percent of the observed atmospheric warming in the Pacific is due to the shroud of soot drifting eastward from Asia. Prof. V. Ramanathan and fellow researchers are reporting that soot's 2.5 W/cu.m. green house effect is partially offset by its surface dimming effect, such that its net effect is still 1 W/cu.m. With the vast Pacific covering 30 percent of the Earth's surface, aerosol soot - black carbon particulates - plays a significant factor in global warming, potentially 12 percent of all global warming.
This westerly mid-atmospheric haze of soot is eventually depleted as it falls on North America. Up to 75 percent of the soot hitting the Western USA is from China, potentially causing 30 percent of regional warming in the Western USA. It's also believed as sooty snowfall is deposited in the American Sierras and Rockies, the dirty snow actually causes earlier snow melts and glacier loss as a result of the increased heat absorption from soot-darkened snow and ice.
There's actually good news in all this: Unlike greenhouse gases which can persist for decades, soot disperses within a few months, if not weeks. With the research indicating that soot is responsible for up to 90 percent of the loss of Arctic sea ice & earlier tundra thaws - accounting for nearly 25 percent of all global warming - readily-implemented soot abatement technologies could go a long way in curbing global climate change.
The globe-spanning effects of soot in the vast Asian Brown Cloud might actually account for easily a third of all observed global warming. Were China to scrub soot from its smokestacks the world might be able to breath a sigh of relief as other emission-curbing technologies are phased in.