According to a new study, black carbon emissions—or 'soot'—generated from burning the world's forests, grasslands and diesel exhaust may have twice the impact on rising temperatures and global warming than previously thought.
And, given the amount of soot emitted each year globally, successful efforts to reduce such pollution could have widespread impact in terms of addressing the role it plays in climate change, say researchers.
Durwood Zaelke, president of the Institute for Governance and Sustainable Development, told the Washington Post that reducing soot emissions "could save lives" and produce impressive results in terms of "cooling" a warming planet.
The study (pdf), published in the Journal of Geophysical Research Atmospheres, suggests that pollution from soot could be even more harmful than methane, widely cited in scientific circles currently as the second-most impactful and most singularly potent of the greenhouse gasses.
According to the study's abstract, "We estimate that black carbon ... is the second most important human emission in terms of its climate-forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing."
Black carbon is a significant cause of the rapid warming in the Northern Hemisphere at mid to high latitudes, including the northern United States, Canada, northern Europe and northern Asia, the report finds, but impacts can also be felt farther south, inducing changes in rainfall patterns from the Asian Monsoon.
"There are exciting opportunities to cool climate by reducing soot emissions but it is not straightforward," said the report's co-author Professor Piers Forster of the University of Leeds' School of Earth and Environment.
The Guardian reports that about 7.5 million tons of man-made soot was released in 2000 alone, with a greenhouse effect two-thirds that of carbon dioxide, and greater than methane. The Guardian continues:
The biggest source of soot emissions is the burning of forest and savannah grasslands. But diesel engines account for about 70% of emissions from Europe, North America and Latin America.
In Asia and Africa, wood burning domestic fires make up 60% to 80% of soot emissions. Coal fires are also a significant source of soot in China, parts of Eastern Europe, and former Soviet bloc countries.
The four-year study, led by the International Global Atmospheric Chemistry Project, notes that emissions in some regions are probably even higher than estimates.
While mitigating black carbon will help curb short-term climate change, "to really solve the long-term climate problem, carbon dioxide emissions must also be reduced," co-lead author Tami Bond of the University of Illinois at Urbana-Champaign said.