Climate disruption adds wallop to Nemo

Intro

New England is preparing for what is anticipated to be up to 30 inches of snow from nor’easter Nemo, which will also bring hurricane force winds and coastal flooding from storm surges.  Abnormally warm offshore waters are adding to the strength of Nemo, increasing the amount of precipitation it carries. Sea levels, elevated by climate change, may increase the reach of Nemo’s storm surge.  Following the severe storms of 2012, a blizzard like Nemo is now part of a pattern of extreme weather driven by climate disruption.

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RT @tcktcktck As a huge winter storm bears down on Boston and NYC@ClimateCentral breaks down what to expect http://ht.ly/hwldW#climate#nemo

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Key Points

  • Warmer sea surface temperatures, caused by both climate change and natural variability, are increasing the precipitation carried by storms like Nemo. Water temperatures off the northeast coast are currently higher than normal, feeding the storm with additional moisture and increasing the potential for heavy precipitation inland.  Current computer-model simulations show Nemo will produce upwards of 30 inches of snow in the Boston area, which would be a new record for the city.
  • As with Hurricane Sandy, sea level rise can contribute significantly to the intense nature of a storm like Nemo by increasing the height of storm surges.  Sea level rise, which is strongly linked to climate change, gives storm surges a higher launching pad and increases the likelihood of destructive coastal flooding. This is especially true on the Northeast coast of the U.S., where sea levels are rising faster than the global average.  According to the draft National Climate Assessment report, even without any changes in the intensity of storms, by 2100 sea level rise will triple the likelihood of coastal flood events.  This means that flood events which previously occurred once every ten years will instead happen every once every three years.
  • Nemo is the latest example of a pattern of more frequent extreme rain and snowfall events driven by climate change. The last century has witnessed a 20% increase in the amount of precipitation falling in the heaviest rain and snow events, a pattern that is directly tied to climate disruption. The Northeast has been particularly vulnerable, experiencing a dramatic increase in one-day precipitation extremes during the October to March cold season.

Background

Though climate skeptics will likely herald the blizzard brought by Nemo as ‘cold’ proof that global warming is false, Nemo is part of a larger pattern of storms with greater precipitation due to the influence of climate change.  This extreme nor’easter, anticipated to bring what could be record-breaking snowfall to Boston and Providence, comes after a year of unprecedented weather events that included heat waves, wildfires, droughts, and violent storms.

When it comes to storms like Superstorm Sandy and Nemo, climate change is said to stack the deck unfavorably so that these storms are likely to be more intense. First, warmer waters offshore allow storms to hold more moisture, increasing the amount of rain that can be carried by a storm. Secondly, rising sea levels, caused by arctic ice melt and the expansion of warm water, increase the height of waves and storm surges.

Given the pattern of extreme storms seen in the past 12 months, bold climate action is needed now.  The draft National Climate Assessment, released in January 2013, delineates potential impacts in both high and low emissions scenarios. The dramatic range of impacts is these scenarios makes one thing clear: action to reduce emissions to mitigate impacts is needed immediately, and Americans must invest in measures to prepare for and adapt to the consequences of this ‘new normal.’

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Quotes

  • “Climate change amps up… basic factors that contribute to big storms… The oceans have warmed, providing more energy for storms, and the Earth’s atmosphere has warmed, so it retains more moisture which is drawn into storms, and is then dumped on us.” Mark Fischetti, Senior Editor of Scientific American
  • “This is just the beginning. I’m not saying there’s going to be a Sandy every weekend or every year, but every decade we can expect more and more stronger storms.” Bill Nye the Science Guy

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