XKCD creator Randall Munroe has gotten it absolutely, hilariously right with his newest comic, addressing the polar vortex trolls who insist that cold weather somehow disproves climate change:
Climate Central, a crucial source of this sort of vital information, is naturally tickled to have been cited by the legendary web comic. The site's original analysis, while lacking the funny, dazzles with some very convincing data:
Climate Central calculated the number of nights below a specific temperature threshold for dozens of U.S. cities based on the local climatology and current weather conditions. The calculations encompass the entire winter season, and show that overall there is a downward trend in the number of extreme cold nights like we’re currently experiencing – although there are variations in a few cities. This trend is consistent with climate studies showing that overall, winters across the contiguous U.S. have warmed by .61°F per decade since 1970, and every region has warmed at least somewhat over that time.
...For example, in Minneapolis in the 1970s (1969-79), there were an average of 14.7 nights with temperatures below minus 10°F. But in the past decade (2002-2012), that number has fallen dramatically, to about 3.8. The calculations run from July through June of the following year, so that we wouldn't break up the winter season.
In Detroit in the 1970s, there were an average of 7.9 nights with temperatures below zero degrees. But now, that number is closer to 2 nights. And in Washington D.C., the number of nights with a low of 20 or below was 13.5 in the 1970s, but was closer to 8.3 in the past decade. The overnight low at Reagan National Airport on Jan. 7 was 6°F.
And in St. Louis, the 1970s featured an average of 3.8 nights with a low of 0°F or below, yet in the past decade, the average for such frigid nights fell to zero.