U.S. Smashes Previous Lower-48 Heat Record in 2012Brian K. Sullivan
Last year was the warmest on records going back to 1895 for the 48 contiguous U.S. states and the second-worst for weather extremes including drought, hurricanes and wildfires, according to a U.S. report.
The average temperature in the region in 2012 was 55.3 degrees Fahrenheit (12.9 Celsius), 3.2 degrees higher than the average for the 20th century, the National Oceanic and Atmospheric Administration’s Climatic Data Center said today in an analysis of the year.
U.S. Climate Extremes Index, which takes into account temperatures as well as tropical storms and drought, showed 2012 followed 1998 into the record books for extreme weather with almost twice the average value, the center said. Eleven disasters caused at least $1 billion in damage, including hurricanes Isaac in August and Sandy in October.
“The heat we saw in the U.S. is consistent with what we expect in a warming world,” Deke Arndt, chief of the climate monitoring branch at the center, said on a conference call. “It’s a huge exclamation point on the end of several decades.”
The 2012 heat surpassed 1998’s record by 1 degree, a significant amount considering that only 4.2 degrees separate 1998 from the coldest year on record, 1917, said Jake Crouch, a climate scientist at the center in Asheville, North Carolina. The warmth is a reflection of natural variability as well as the impact of climate change, he said.
“I’m afraid it’s just the new normal,” said Robert Marshall, founder of Earth Networks in Germantown, Maryland. “At the end of the day, the trend is pretty clear.”
Each of the lower 48 states had an annual temperature that was higher than average, the center said. Nineteen set records.
Last summer had the third-highest population-weighted cooling demand since 1950, Mark Russo, a meteorologist for Chesapeake Energy Corp., said during a presentation today at the annual meeting of the American Meteorological Society.
The 30-year average for cooling-degree days for the months of June, July and August is 1,156, while the 10-year average is 1,208 and the five year average is 1,246, a trend that indicates summers have been getting warmer, Russo said. Cooling-degree days are an indication of weather-related demand for electricity.
Last year fit a pattern of heat events lasting longer and becoming more extreme, as might be expected with climate change, Arndt said.
The high temperatures also added to the drought that choked shipping on the Mississippi, Missouri and Ohio rivers as channels got shallower, limiting loads.
The year was the 15th driest on record, the worst since 1988, with total precipitation of 26.6 inches (67.6 centimeters), 2.6 inches below average. For Nebraska and Wyoming, 2012 was the driest year ever.
The extent of last year’s drought was “roughly equal” to that of the 1950s, although both were smaller than the Dust Bowl of the 1930s, according to the center.
“The current drought has yet to reach the intensity or duration of the 1950s and 1930s national-scale droughts,” the center said.
More than 9 million acres were consumed by wildfires in 2012, placing the year third in records going back 13 years. Tornado activity was lower than the average for 1991-2010 and the year may have had the fewest twisters since 2002 with a final count lower than 1,000, the center said.