Sunday, April 15, 2012

Viz: Yikes! I thought march was warm. Warmest in 200 years

Frequent outliers aren't outliers. 

Ars Technica

As record temperatures swept through the Midwest and trees bloomed early across the Northeast, lots of talk focused on what an unusually warm start spring was having. The folks at the National Oceanic and Atmospheric Administration have now crunched the numbers, and found that it wasn't just unusually warm—March was bizarrely hot. With 15,000 record high temperatures set in the US, it was far and away the warmest March in the nation's history, and only a single month—January of 2006—was as far off from the monthly average.

Only one of the 48 contiguous states (Washington) was below normal, and a huge slice down the center of the country was bathed in bright red in NOAA's map, indicative of record high temperatures. The heatwave was partly responsible for moving the first quarter of the year into the top slot of the US record books. The high temperatures also kicked off an unusually early spring cluster of tornadoes in the Midwest.

Neither NASA nor NOAA have managed to do the global monthly averages yet, so it's not clear if our experience was shared by much of the rest of the planet (the US occupies a relatively small fraction of its surface). So far this year, the global means have been pretty mundane. They're above last century's average, but not by a lot, and every month has been above that average since early 1994.

NOAA indicates that it was a specific weather pattern that pushed heat into the central US. One of the key drivers of global temperature, the tropical Pacific's surface temperatures, remain in a cooler, La Niña state, so it's unlikely the rest of the world shared in our warmth.