Scientists say they've accumulated enough research to feel comfortable attributing much of the warming that has occurred globally since about 1950 to humans.
At about 1980, that warmth began accelerating.
The December temperature records for Omaha appear to bear that out.
Omaha hasn't seen a record cold December night in almost 20 years — since 1994.
Outbreaks of extreme cold occur less frequently as the planet warms. Also, warmer nights and warmer winters are markers of climate change, so it's not surprising to see a decline in record lows.
Before 1950, 11 years accounted for record low temperatures in December in Omaha. Since then, five years have accounted for record cold nights.
The main source of those records was December 1983, the coldest December on record in Omaha and in the nation.
The 1983 outbreak was unusual, not only for its intensity and duration, but also for occurring in the latter half of the last century, said Barbara Mayes, meteorologist with the National Weather Service in Valley.
Here is a summary of the years in which record lows were set in December in Omaha:
(Warming becomes more noticeable in climate records.)
Source: National Weather Service