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2010-02-11 11:51:02
By BRYAN WALSH Bryan Walsh Wed Feb 10, 3:50 pm ET
As the blizzard-bound residents of the mid-Atlantic region get ready to dig
themselves out of the third major storm of the season, they may stop to wonder
two things: Why haven't we bothered to invest in a snow blower, and what
happened to climate change? After all, it stands to reason that if the world is
getting warmer - and the past decade was the hottest on record - major
snowstorms should become a thing of the past, like PalmPilots and majority rule
in the Senate. Certainly that's what the Virginia state Republican Party
thinks: the GOP aired an ad last weekend that attacked two Democratic members
of Congress for supporting the 2009 carbon-cap-and-trade bill, using the recent
storms to cast doubt on global warming. (See pictures of the massive blizzard
in Washington, D.C.)
Brace yourselves now - this may be a case of politicians twisting the facts.
There is some evidence that climate change could in fact make such massive
snowstorms more common, even as the world continues to warm. As the
meteorologist Jeff Masters points out in his excellent blog at Weather
Underground, the two major storms that hit Philadelphia, Baltimore and
Washington, D.C., this winter - in December and during the first weekend of
February - are already among the 10 heaviest snowfalls those cities have ever
recorded. The chance of that happening in the same winter is incredibly
unlikely.
But there have been hints that it was coming. The 2009 U.S. Climate Impacts
Report found that large-scale cold-weather storm systems have gradually tracked
to the north in the U.S. over the past 50 years. While the frequency of storms
in the middle latitudes has decreased as the climate has warmed, the intensity
of those storms has increased. That's in part because of global warming -
hotter air can hold more moisture, so when a storm gathers it can unleash
massive amounts of snow. Colder air, by contrast, is drier; if we were in a
truly vicious cold snap, like the one that occurred over much of the East Coast
during parts of January, we would be unlikely to see heavy snowfall. (See
pictures of the effects of global warming.)
Climate models also suggest that while global warming may not make hurricanes
more common, it could well intensify the storms that do occur and make them
more destructive. (Comment on this story.)
But as far as winter storms go, shouldn't climate change make it too warm for
snow to fall? Eventually that is likely to happen - but probably not for a
while. In the meantime, warmer air could be supercharged with moisture and, as
long as the temperature remains below 32 F, it will result in blizzards rather
than drenching winter rainstorms. And while the mid-Atlantic has borne the
brunt of the snowfall so far this winter, areas near lakes may get hit even
worse. As global temperatures have risen, the winter ice cover over the Great
Lakes has shrunk, which has led to even more moisture in the atmosphere and
more snow in the already hard-hit Great Lakes region, according to a 2003 study
in the Journal of Climate. (Read "Climate Accord Suggests a Global Will, if Not
a Way.")
Ultimately, however, it's a mistake to use any one storm - or even a season's
worth of storms - to disprove climate change (or to prove it; some
environmentalists have wrongly tied the lack of snow in Vancouver, the site of
the Winter Olympic Games, which begin this week, to global warming). Weather is
what will happen next weekend; climate is what will happen over the next
decades and centuries. And while our ability to predict the former has become
reasonably reliable, scientists are still a long way from being able to make
accurate projections about the future of the global climate. Of course, that
doesn't help you much when you're trying to locate your car under a foot of
powder.