The warm Christmas weather on the East Coast wasn’t an anomaly by historic standards, as shown by the professor. The National Weather Service backs up the professor’s claim by reporting that Christmas Eve temperatures in the District of Columbia were above 65 degrees in 1964, 1982, 1965, 1932, 1889, and 1893.
The warmest winters in American history occurred from 1950-1954, when nearly one out of four January days was over 60 degrees. Recent January averages show that only one out of every six days is over 60 degrees.
Bernie Sanders’s claim also ignores analysis by the National Oceanic and Atmospheric Administration (NOAA). When asked by National Public Radio if global warming was playing a role in recent warm winter temperatures, the deputy director of NOAA’s Climate Prediction Center Mike Halpert responded:
If it is, it’s probably fairly insignificant at this point. If it were to play a role, it would be more likely if, somehow, climate change is impacting either the Arctic oscillation or El Nino, and we’re not really aware that it is at this point. If you think about, maybe – the high temperature over the weekend was 70, so maybe without climate change, it would’ve been 69. I think it’s a fairly insignificant role, if any role at all.
Halpert says the unseasonably warm weather is due to an “arctic oscillation,” which traps cold air in the Artic. An unusually strong El Nino, a climate event which causes ocean temperatures to rise, is also responsible. Both weather events are not related to global warming.