Smut is a bigger problem than greenhouse gases in polar meltdown
Belching from smokestacks, tailpipes and even forest fires, soot—or black carbon—can quickly sully any snow on which it happens to land. In the atmosphere, such aerosols can significantly cool the planet by scattering incoming radiation or helping form clouds that deflect incoming light. But on snow—even at concentrations below five parts per billion—such dark carbon triggers melting, and may be responsible for as much as 94 percent of Arctic warming.
"Impurities cause the snow to darken and absorb more sunlight," says Charlie Zender, a climate physicist at the University of California, Irvine. "A surprisingly large temperature response is caused by a surprisingly small amount of impurities in snow in polar regions."