That this has been a week of astonishing weather is pretty well documented on the news and in social media. I was away visiting family in a famously warmer part of the United States, where temperatures were about 80 degrees (and I brought along two sweaters for whatever reason). The trip back home was hard because winter weather forced me to fly into a different airport, then I faced a long drive back on messy roads going half the speed limit most of the way. Three days later the temperature had climbed to fifty degrees, and the masses of snow began to melt. Then on Monday I watched the temperature plummet in the afternoon to the coldest I have ever experienced (which is not saying much, having spent most of my life in warmer climes). Now my trip to the MLA convention has been delayed because the weather interrupted this week’s travel plans.
The cold weather predictably brought out the usual suspects of global warming denialists, trotting out arguments that are barely worth taking seriously save as case studies in irrational defense mechanisms. What’s interesting is that we living in the middle latitudes can expect more severe cold with global warming. If I may make an institutional plug, two Cornell professors, Charles Greene and Bruce Monger, published on this very phenomenon in 2012.
A warmer Earth increases the melting of sea ice during summer, exposing more dark ocean water to incoming sunlight. This causes increased absorption of solar radiation and excess summertime heating of the ocean — further accelerating the ice melt. The excess heat is released to the atmosphere, especially during the autumn, decreasing the temperature and atmospheric pressure gradients between the Arctic and middle latitudes.
A diminished latitudinal pressure gradient is linked to a weakening of the winds associated with the polar vortex and jet stream. Since the polar vortex normally retains the cold Arctic air masses up above the Arctic Circle, its weakening allows the cold air to invade lower latitudes.
On an only tangentially related note, I was sorting my digital photos from 2014 and came upon this one. Here I am during a camping trip on an island in the Adirondacks. I’ll offer it as a pleasant memory of the warmer months. What I have in my hand is the best cup of coffee I drank in all of 2013!