Several of my previous posts  have examined the remarkable weather of the past year, including the unusual U.S. East Coast snowstorms  this winter, the wide array of floods and heat waves  this summer, and how these can help us understand our vulnerabilities  to climate change. The average land surface temperature this summer (June-August) was the warmest on record globally  and the fourth warmest on record in the United States .
Now that northern summer has come to a close, we can take stock of just how warm it was. Christopher C. Burt —weather historian, extreme-weather guru, and author —takes a look at temperature records set in the U.S. and around the world this summer in his blog  at Weather Underground. Some of his findings include:
It’s important to put this single year into a broader perspective; if this warmth is just an aberration, then we might be wasting time talking about it. But it is clearly part of a much longer warming trend that has been going on for decades. A recent report  from the National Oceanographic and Atmospheric Administration announced that 2009 was one of the ten warmest years on record (since 1880) and that the 2000s was the warmest decade followed by the 1990s and then the 1980s. If the first 9 months of this year are an indication, the 2010s appear poised to continue this upward march in temperatures.
(Figure Source: NOAA’s State of the Climate in 2009 , Chapter 2)
Jay Gulledge is Senior Scientist and Director of the Science and Impacts Program