The Particle-Emissions Dilemma
STOCKHOLM – Particle emissions into Earth’s atmosphere affect both human health and the climate. So we should limit them, right? For health reasons, yes, we should indeed do that; but, paradoxically, limiting such emissions would cause global warming to increase. Why?
The combustion of fossil fuels, wood, and other biomass increases the amount of airborne particles, which, in a somewhat simplified manner, we can describe as “white” or “black.” Both types can be found in varying amounts in all emissions. Most black particles stem from small-scale and inefficient burning of biofuels, and, in Asia and Africa, from the burning of agricultural waste. By contrast, white particles consist largely of sulfur from the burning of coal and oil.
Because black particles contain soot and absorb sunlight, they are believed to increase global warming. White particles, however, reflect some of the incoming sunlight back into space, producing a cooling effect on Earth’s climate.