Last year was the warmest on record in the United States and the second most extreme for droughts, wildfires, hurricanes, and storms, according to a report from the National Oceanic and Atmospheric Administration.
A brutal combination of a widespread drought and a mostly absent winter pushed the average annual US temperature last year up to 55.32 degrees Fahrenheit. That’s a full degree warmer than the old record set in 1998.
Breaking temperature records by an entire degree is unprecedented, scientists say. Normally, records are broken by a tenth of a degree or so.
The news continues a dramatic warming trend in the mainland United States: Seven of the top 10 warmest years in the 48 states have occurred in the past 15 years, NOAA said. It comes as the earth continues to heat up from the release of carbon dioxide and other greenhouse gases from power plants, cars and factories.
New England reflected a similar trend: Boston, Hartford, Providence, Burlington, Vt., and other communities experienced record or near-record warming in 2012. Water temperatures off New England are also expected to top the record books once a final analysis is completed.
Scientists say they cannot attribute the warming air –- or water -- temperatures solely to global warming, but they note that global atmospheric and sea temperatures are steadily rising. The news comes as environmentalists begin to push President Obama more aggressively to deal with climate change in his second term.
“Our planet is warming, our oceans are rising, and our storms are strengthening. Congress can no longer afford to watch the devastation from an air conditioned perch,’’ said US Representative Edward Markey in a statement. “We must make 2013 a year for climate action. Waiting around for the next superstorm to flood Boston’s Faneuil Hall or the Boston Garden is not an option.”
To date, 2012 has seen 11 extreme weather disasters that have reached the $1 billion threshold in losses, including Sandy, Isaac, and tornado outbreaks experienced in the Great Plains, Texas and Southeast/Ohio Valley, the report notes.
‘‘These records do not occur like this in an unchanging climate,’’ said Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research in Boulder, Colo. ‘‘And they are costing many billions of dollars.’’
Last year was 3.2 degrees warmer than the average for the entire 20th century. Last July was the also the hottest month on record.
Nineteen states set yearly heat records in 2012. Alaska, however, was cooler than average.
US temperature records go back to 1895 and the yearly average is based on reports from more than 1,200 weather stations across the Lower 48 states.
The last time the country had a record cold month was December 1983.
‘‘A picture is emerging of a world with more extreme heat,’’ said Andrew Dessler, a Texas A&M University climate scientist. ‘‘Not every year will be hot, but when heat waves do occur, the heat will be more extreme. People need to begin to prepare for that future.’’