Photo by Tim Boyle/Getty Images.
The average temperature in the contiguous United States over the past 12 months was the warmest ever recorded, the government announced Tuesday.
The National Oceanic and Atmospheric Administration report found that the average temperature in the lower 48 over the 12-month stretch ending in April was 55.7 degrees Fahrenheit, the warmest average since record-keeping began in 1895 and 2.8 degrees above the 20th century average.
The past 12 months included both the second hottest summer on record and the fourth warmest winter, along with the warmest ever March. All that was good enough for to eek out the top spot from the previous record holder, set in November 1999 to October 2000, by 0.1 degree.
Even more troubling for climate watchers: All 10 of the warmest 12-month periods on record have occurred in the past 15 years.
The Washington Post explains that scientists believe the culprit for the exceptional warmth this year are jet stream patterns that have created heat domes over the middle of the country. The paper says the persistence of such patterns in recent years is "very likely related" to human activity.
The NOAA’s Storm Prediction Center also noted in the report that there were 228 reported tornadoes in April, above average but still down sharply from last year’s historic spring, when 750 tornadoes were reported in April alone.