Is dirty air adding to climate change?

Bright white sea ice reflects light and keeps the Arctic cool. Soot darkens the ice surface and can speed melt. Credit: Andy Mahoney, NSIDC

Soot: it’s bad for human health, and bad for the health of the Earth, too. According to new research, it’s speeding up the loss of sea ice in the Arctic—ice that is vital to keeping the Earth cool. The Arctic’s summer covering of sea ice fell 30 percent over the last thirty years, and researchers expect that downward trend to continue. Scientists say that CO2 emissions account for much of the ice loss. But soot plays a role as well, and it might be easier to control.

How much is soot contributing to the problem? More than we thought, according to Mark Jacobson at Stanford University. It works like this: as sea ice melts, larger areas of open water absorb heat and add to ice melt. Soot falls on sea ice and amplifies that effect by making the ice surface darker and less reflective. “Black carbon over snow absorbs not only sunlight coming down but also sunlight reflected off of snow and ice coming back up,” Jacobson said. His study, published last summer in Journal of Geophysical Research, showed that soot particles are second only to greenhouse gases in the decline of Arctic sea ice. Continue reading