March 16, 2007 — There may be an unexpected sooty surcharge on all those cheap Chinese imports, say atmospheric scientists. The carbon soot from China is warming and polluting the atmosphere over the Pacific Ocean and all the way to North America, according to a new study.
The effect on the Pacific Ocean, the largest and most influential ocean on the planet, could have global climate implications, the study's authors conclude.
The airborne soot dims sunlight reaching the surface, causing cooling there, but it also heats the air higher where it resides, resulting in an overall heat gain for the climate.
The effect on the North Pacific is that the dimming could be lowering the amount of evaporation, and therefore rain and snowfall, while adding to greenhouse effect.
"It affects the hydrological cycle," said atmospheric researcher V. Ramanathan of the Scripps Institution of Oceanography at the University of California, San Diego. Ramanathan has examined similar effects in the Indian Ocean, where dimming caused by soot has cooled waters and now lessens or blocks the annual Indian Monsoon — with devastating economic and ecological consequences for India and neighboring nations.
"I'm getting concerned what's happening closer to home," Ramanathan told Discovery News, regarding the new study published in the Journal of Geophysical Research.
In that study he, Odelle Hadley and their colleagues used data on soot gathered at air stations in North America, as well as from aircraft, to get a better idea how much soot, also called black carbon, is making it across the ocean.
The researchers used that information in a simulation to calculate the amounts of energy, and therefore heat, being blocked or added at the surface level and at about 7,000 feet above sea level, in March and April.
Over the Pacific it appears that soot allows higher air to absorb 2 to 2.5 watts more sunshine per square meter, the team reported.
Down at the ocean surface, the dimming effect reduces solar heating by almost 1.5 watts per square meter. That means the soot creates a net heat gain to the atmosphere of about 0.5 to 1 watt per square meter.
Soot is a small but critical part of the pollution that blows off of eastern Asia. The sources of the soot include diesel exhaust, agricultural burning and cooking fires.
