It's official: 2012 was the hottest year ever in the U.S.

Last year was pretty messed up as far as weather was concerned in the United States, and now we have the numbers to show why. According to the National Climatic Data Center in Asheville, N.C., the average temperature in 2012 was 55.3 degrees Fahrenheit (12.94 degrees Celcius) — an entire degree higher than the previous record. Moreover, there were 34,008 daily high records set at weather stations across the contiguous U.S., compared to only 6,664 record lows — a figure that, as early as the 1970s, was in relative balance.

Usually when records are set they are measured in fractions of a degree. But not last year. Unsurprisingly, meteorologists and climate scientists are treating it as a big deal. The New York Times reports:

Scientists said that natural variability almost certainly played a role in last year's extreme heat and drought. But many of them expressed doubt that such a striking new record would have been set without the backdrop of global warming caused by the human release of greenhouse gases. And they warned that 2012 was probably a foretaste of things to come, as continuing warming makes heat extremes more likely.

Globally, the year won't set a new standard, but it's expected to be the eigth- or ninth-warmest on record — meaning that the 10 warmest years on record have all fallen within the past 15 years. Again from the NYT:

Nobody who is under 28 has lived through a month of global temperatures that fell below the 20th-century average, because the last such month was February 1985.

Last year's weather in the United States began with an unusually warm winter, with relatively little snow across much of the country, followed by a March that was so hot that trees burst into bloom and swimming pools opened early. The soil dried out in the March heat, helping to set the stage for a drought that peaked during the warmest July on record.

The drought engulfed 61 percent of the nation, killed corn and soybean crops and sent prices spiraling.

And of course, there were several tornado outbreaks, Hurricane Isaac, and Superstorm Sandy. In fact, the year featured 11 disasters exceeding $1 billion in damages. And a third of the U.S. population experienced 10 or more days of summer temperatures exceeding 100 degrees Fahrenheit (37.7 degrees Celcius).

The NOAA's report opened with the following paragraph:

2012 marked the warmest year on record for the contiguous United States with the year consisting of a record warm spring, second warmest summer, fourth warmest winter and a warmer-than-average autumn. The average temperature for 2012 was 55.3°F, 3.2°F above the 20th century average, and 1.0°F above 1998, the previous warmest year.

More here and here.

Image via New York Times.