Evidence of Long-Term Warming in the USA


A compilation of daily record temperatures from nearly 2000 weather stations in the continental U.S. shows that daily record high temperatures occurred twice as often as record lows over the last decade. This is evidence of the average warming shifting the odds towards a greater chance of setting a record high than a record low. Climate model projections show that this ratio continues to grow with further warming. For example, in one future scenario, record highs outnumber record lows 20 to 1 by mid-century, and 50 to 1 by end of century. Even in a much warmer future climate, extreme cold with record-setting minimum temperatures still occurs, but are greatly outnumbered by record high temperatures. This study, led by Dr. Jerry Meehl, was co-sponsored by the Department of Energy and the National Science Foundation.


Meehl, G.A., et al. 2009. “The Relative Increase of Record High Maximum Temperatures Compared to Record Low Minimum Temperatures in the U.S.,” Geophysical Research Letters 36, L23701, doi:10.1029/2009GL040736.