Soot ranks as the second-largest human contributor to climate change, according to a new analysis released Tuesday, exerting twice as much of an impact as previously thought.
The four-year, 232-page study of black carbon, published in the Journal of Geophysical Research: Atmospheres, shows that short-lived pollution known as soot, such as emissions from diesel engines and wood-fired stoves, has about two-thirds the climate impact of carbon dioxide. The analysis has pushed methane, which comes from landfills and other forces, to third place as a human contributor to global warming.
Black carbon, or soot, accelerates warming because the fine particles absorb heat when they are in the air and when they darken snow and ice. Although some lighter-colored fine particles can have a cooling effect because they block sunlight, other black carbon sources have a warming effect because they absorb it. They also accelerate glacier melting and can disrupt regional weather patterns.
The findings came out on the same day that the National Oceanic and Atmospheric Administration announced last year’s global average temperature ranked as the 10th-warmest on record, and NASA found it was the ninth-warmest. The two agencies analyze temperature data differently, but both found that with the exception of 1998, the nine warmest years since 1880 all have occurred since 2000.