Science / Medicine : Pollutants May Have Masked Global Warming

Air pollutants belched out since the beginning of the Industrial Revolution may have offset much of the global warming caused by “greenhouse gases,” such as carbon dioxide, researchers said last week. A team headed by atmospheric scientist Robert Charlson of the University of Washington reported in the journal Science that sulfur dioxide and other sulfate pollutants can cause increased atmospheric haze that reflects sunlight back into space, thereby compensating for warming that would otherwise be caused by the greenhouse effect.

“This may mean that we already have a far worse problem with global warming than we realize, because the effects of greenhouse gases have been masked,” said co-author James Coakley of Oregon State University. Unfortunately, he added, the sulfates are themselves a problem, causing acid rain, which damages trees, crops, marine life and buildings. “If we take steps to remove these sulfates from our industrial processes, it could rapidly compound greenhouse warming,” he said.

“Some of these effects have been understood on a superficial level for decades,” Coakley said. “But until we really studied their impact, we didn’t realize what a large offset they would provide to greenhouse warming.”