The global warming debate has focused on carbon dioxide emissions, but scientists at UC Irvine have determined that a lesser-known mechanism – dirty snow – can explain one-third or more of the Arctic warming primarily attributed to greenhouse gases.
If this is true it suggests we can greatly reduce ice melting by cutting back on particulates pollution from burning coal and other fossil fuels. Cutting back on the particulates would also reduce health harm from particulates. One of my recurring arguments on energy and environmental policy is that we should cut back on conventional air pollutants as a higher priority than reduction of carbon dioxide emissions. Here's evidence that cleaner burning of fossil fuels will reduce temperatures in the Arctic.
Snow becomes dirty when soot from tailpipes, smoke stacks and forest fires enters the atmosphere and falls to the ground. Soot-infused snow is darker than natural snow. Dark surfaces absorb sunlight and cause warming, while bright surfaces reflect heat back into space and cause cooling.
“When we inject dirty particles into the atmosphere and they fall onto snow, the net effect is we warm the polar latitudes,” said Charlie Zender, associate professor of Earth system science at UCI and co-author of the study. “Dark soot can heat up quickly. It’s like placing tiny toaster ovens into the snow pack.”
The study appears this week in the Journal of Geophysical Research.
The rapid rate at which China is building coal-fired electric power plants (1-2 per week) suggests the snow is going to get even more soot-infused in coming years.
Our snow is too dirty.
In the past two centuries, the Arctic has warmed about 1.6 degrees. Dirty snow caused .5 to 1.5 degrees of warming, or up to 94 percent of the observed change, the scientists determined.
Forest fires also generate soot that lowers albedo and heats up snow in the Arctic.
The Chinese aren't going to shift away from coal toward cleaner energy sources until the alternatives drop in price. However, as their living standards increase we can expect they will try harder to reduce emissions from their coal burning industries as their higher affluence causes them to see cleaner air as a higher priority. But their living standards have a long way to rise before they'll want to treat emissions controls as a high priority.
|Share |||Randall Parker, 2007 June 09 11:12 PM Climate Trends|