Dirty snow - as bad as CO2?
Scientists at the University of California in Irvine (UCI) have discovered that dirty snow is likely to have caused nearly 19% of the total global warming experienced (0.8 degrees Celsius) over the last 200 years. Throughout that same period, the Arctic warmed by approximately 1.6 degrees, with some estimates showing dirty snow contributing as much as 1.5 degrees (or up to 94% of the observed increase).
Dirty snow arises from the soot that escapes from exhaust pipes, smoke stacks and forest fires to enter the atmosphere and then falls to the ground. While clean, white snow tends to reflect back heat into space and cause cooling, the dark surface of dirty snow causes it to absorb sunlight and thus results in warming.
“When we inject dirty particles into the atmosphere and they fall onto snow, the net effect is we warm the polar latitudes,” Charlie Zender, an associate professor of Earth system science at UCI, said. “Dark soot can heat up quickly. It’s like placing tiny toaster ovens into the snow pack.”
In some polar areas, dirty snow has caused enough melting to expose the underlying sea ice or soil that is much darker and thus more apt to absorb sunlight. This has resulted in polar temperatures rising by as much as 3 degrees Celsius during certain seasons.
Zender thinks policymakers should approach this problem by focusing on reducing industrial soot emissions and switching over to cleaner fuels. Making new snow purer by cutting out impurities would cause an immediate cooling in temperatures.
In the automotive world, diesel engines are by far the biggest emitters of soot - let’s hope more automakers start including particulate filters in their diesels ASAP.
Source: Treehugger
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