A look at weather extremes and the big-picture climate connections.

October Snowstorm Adds to 2011’s Billion Dollar Weather Disasters

Insurance company tally puts losses above $3 billion

The massive snowstorm that dumped more than two feet of snow on southern New England last week, making it the heaviest early season snowfall to hit the Northeast and Mid-Atlantic since before the Civil War, may have caused more than $3 billion in damage, according to Aon Benfield, a reinsurance company that provides forecasts about the total losses from extreme weather events and other disasters.

The storm, which hit so early in the season that many trees had not yet lost their leaves, caused branches to snap from the weight of the snow and toppled trees onto power lines, homes, and cars. The result: widespread power outages that left thousands in the dark for days. Connecticut was hit with its the biggest blackout in state history. The snowstorm occurred just two months after the event that previously held that title, Tropical Storm Irene.

This image from NASA's MODIS imager shows the widespread snowcover (in white) left by the "Snowtober" storm.

In fact, the storm caused more extensive tree damage in parts of New York, Connecticut, and Massachusetts than Irene did (luckily the "Snowtober" storm spared Vermont, which suffered severe flooding from Irene). It was also more damaging, in terms of costs, than the infamous "Snowmageddon" that hit the Mid-Atlantic and Northeast in 2010.

According to Aon Benfield: "Additional damage was reported to the transportation infrastructure from Maryland to Maine. At the height of the event, more than three million power outages were recorded."

If the Aon Benfield analysis is correct, then the snowstorm would become the 11th billion-dollar extreme weather event in 2011, a new record for the United States. In fact, as Jeff Masters noted at Wunderground, Aon Benfield's figures show that there have been 14 billion-dollar disasters in 2011. Masters wrote:

Flood damage from the remnants of Tropical Storm Lee in the Northeast on September 8 is now estimated at more than $1 billion, and two outbreaks of severe thunderstorms and tornadoes -- one in April and one in June -- now have damage estimates exceeding $1 billion... Tornadoes, hurricanes, and floods in these fourteen disasters killed over 600 people, putting 2011 into fourth place since 1940 for most deaths by severe storms. 

NOAA maintains the official list of billion dollar natural disasters, and its preliminary list currently shows only 10 such events so far this year. There is one other snowstorm already on NOAA's list, the "Groundhog Day Blizzard" that paralyzed Chicago in February, which caused more than $1.8 billion in damage. 

Climate change studies show that manmade global warming is increasing the likelihood of certain types of extreme events, including heavy precipitation events such as heavy snowstorms, and is making these events more severe as well. On november 18, the U.N. Intergovernmental Panel on Climate Change will release a new report detailing the science of extreme events and global climate change, as well as strategies to adapt to them.

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