.
The year began very warm with the fourth mildest winter on record followed by a record-setting spring, more than five degrees above average.
The early warmth produced a “tremendous green-up” in corn and soybean growing areas of the Midwest and farmers planted their crops as early they could, Karl said.
But this backfired as temperatures continued to climb and rains diminished. July was the hottest month ever recorded in the U.S. and the summer overall ranked second warmest on record.
“An estimated 99.1 million people experienced 10 or more days of summer temperatures greater than 100°F, nearly one-third of the nation’s population,” NCDC said.
The combination of widespread blistering heat and a sustained period of below average precipitation led to disastrous drought conditions. NCDC provided this detail to put the drought in historic context:
The footprint of drought during 2012 roughly equaled the drought of the 1950s which peaked at approximately 60 percent. The size of the current drought and the drought of the 1950s are smaller than the drought episodes of the 1930s. The current drought has yet to reach the intensity or duration of the 1950s and 1930s national-scale droughts.
Karl stressed that the extreme daytime temperatures were a huge factor in the drought’s severity. In past years, Karl said, large parts of the Midwest had experienced unusually warm nighttime temperatures in recent years, but daytime heat had not been so extreme. But 2012 “reversed that trend” Karl said and as many records were set for daytime warmth as nighttime warmth.
“It’s detrimental for crops when the nighttime temperature doesn’t go below 75 -- and when the daytime temperature goes above upper 80s, ” Karl said.
The warm, dry conditions also stoked widespread, record-setting wildfire activity in the West. Overall, 9.2 million acres burned, third most on record. NCDC reports these details:
The Waldo Canyon fire near Colorado Springs, Colorado destroyed nearly 350 homes and was the most destructive fire on record for the state. The Whitewater-Baldy Complex fire charred nearly 300,000 acres and was the largest on record for New Mexico.
Once the summer season ended, temperatures compared to normal were not in record-setting territory but still above average and precipitation remained below average.
Each season of 2012 had below average precipitation and the year as a whole ranked 15th driest on record. As of January 1 (2013), 61 percent of the contiguous U.S. is experiencing at least moderate drought which, unless there is abundant winter and spring precipitation, could mean another very challenging summer ahead for agriculture in the Heartland.
The record-setting average temperatures in 2012 fit into a long-term pattern of warming temperatures in the U.S.
“We’ve entered a stage now, where [the warming trend] is going to be pretty obvious to the man on the street,” Karl said. “[This year’s warmth] doesn’t mean every season and every year will be this warm, but you’re going to see this with increasing frequency.”
Just as temperatures were warm in the U.S., they were also warm globally. Through November, global temperatures ranked 8th warmest on record in 2012. NCDC will release its year-end report for the globe next week.