After an unusually early and warm spring, brutal summer and mild winter, the National Oceanic and Atmospheric Administration (NOAA) officially announced yesterday that 2012 was the warmest year on record for the contiguous 48 United States.
Typically records are broken by tenths of a degree but 2012 shot through the previous record set in 1998 by a full degree Fahrenheit reaching an average temperature of 55.3°F, a full 3.2°F above the 20th century average and shattering the 4.2 degree temperature "envelope" of the 117-year record. NOAA climate scientist Jake Crouch said 2012 was a year without close precedent:
"The heat was remarkable. said Crouch. “It was prolonged. That we beat the record by one degree is quite a big deal. We are well above the pack for all the years we have data for the United States." Though natural variability had its part to play in the oppressive drought and heat experienced last year "climate change has had a role in this," he said.
Every one of the 48 contiguous states experienced above average temperatures in 202012. Nineteen states had a record warm year with an additional 26 experiencing among the 10 warmest years in their states' history. July was the peak warm month within average temperature of 76.9°F, the hottest month ever recorded in the continental United States. Almost one-third of the country's population, about 99.1 million people, endured 10 or more days over the summer with temperatures exceeding 100°F.
July was also the peak month for drought with 61 percent of the country under moderate to severe drought conditions, a drought the continues into 2013.
Skewed ratio of record highs to record lows
According to meteorologist Guy Walton, 34,008 record highs were set in weather stations throughout the country in 2012 and only 6,664 record lows. The ratio of highs to lows was relatively balanced until the 1970's when it started to skew more heavily toward the highs. But that ratio was never as unbalanced as last year.
Warmer years to come - the new normal
Climate scientists see 2012 as a sign of more to come. The "unusually" warm years like 2012 will become much more "usual" - the new normal - in the coming years and decades.
"Going into the future, we would expect warmer years, or years with temperatures much above the 20th century average, to become more frequent," Crouch said. "2012 was an outlier in terms of looking at the past record for the contiguous United States, but as we move forward and the warming trend continues, we would expect to see more warmer-than-average years."
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Image credit: WxMom, courtesy flickr