March weather, 2012 and 2013

 

March 2012 was unusually warm, and March 2013 unusually cold. The short-term explanation appears to lie in the Arctic Oscillation, as described in the NOAA video above. The cold March came at the tail end of a cold winter.

But there seems to be a longer-term possible explanation appearing as well. Remember climate and weather are two different things, and this video describes the weather. But yes, the climate is changing. And one of the effects appears to be on sudden stratospheric warming events like the one that occurred last January.

Sudden stratospheric warming events take place in about half of all Northern Hemisphere winters, and they have been occurring with increasing frequency during the past decade, possibly related to the loss of Arctic sea ice due to global warming. Arctic sea ice declined to its smallest extent on record in September 2012.

And yes, sudden stratospheric warming events can affect the Arctic Oscillation. You can read more about them here. As they say, you can expect the climate; the weather is what you get.  

Update, May 6: There's an interesting interview with meteorologist Paul Huttner here. He talks about the unusual weather events we've been seeing, like last week's late snowstorm. And how that's a weather event, but there are lots of signs of regional climate change around the world.