An epic blizzard is bearing down on New England — fed in part by relatively warm coastal waters.
I asked Dr. Kevin Trenberth, former head of the Climate Analysis Section at the National Center for Atmospheric Research, to comment on the role climate change has on this storm. He explained:
- This is a perfect set up for a big storm, with the combination of two parts: a disturbance from the Gulf region with lots of moisture and a cold front from the west.
- Ingredients for a big snow storm include temperatures just below freezing. In the past temperatures at this time of year would have been a lot below freezing but the ability to hold moisture in the atmosphere goes down by 7% per degree C (4% per deg F), and so in the past we would have had a snow storm but not these amounts.
- The moisture flow into the storm is also important and that is enhanced by higher than normal sea surface temperatures (SSTs). These are higher by about 1 deg C [almost 2°F] than a normal (pre-1980) due to global warming and so that adds about 10% to the potential for a big snow.
Every storm and “event” is unique. It always has unique ingredients. So it is hard if not impossible to take apart, because any piece missing means the storm behaves differently. So event attribution is not well posed. Instead we look for the environment in which the storm is occurring and how that has changed to make conditions warmer and moister over the oceans.
Like a baseball player on steroids, our climate system is breaking records at an unnatural pace. And like a baseball player on steroids, it’s the wrong question to ask whether a given home run is “caused” by steroids. As Trenberth wrote in his must-read analaysis, “How To Relate Climate Extremes to Climate Change,” the “answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be.” ….(more).