I’ll take credit for this one. I casually noticed that the monthly average temperatures at National were departing from their 1981–2010 averages a couple of degrees relative to those at Dulles — in the warm direction.
Temperatures at National are almost always higher than those at Dulles, 19 miles away. That’s because of the well-known urban warming effect, as well as an elevation difference of 300 feet. But the weather systems that determine monthly average temperature are, in general, far too large for there to be any significant difference in the departure from average at two stations as close together as Reagan and Dulles. Monthly data from recent decades bear this out — until, all at once, in January 2014 and every month thereafter, the departure from average at National was greater than that at Dulles.
The average monthly difference for January 2014 through July 2015 is 2.1 degrees Fahrenheit, which is huge when talking about things like record temperatures. For example, National’s all-time record last May was only 0.2 degrees above the previous record.
Earlier this month, I sent my findings to Jason Samenow, a terrific forecaster who runs the Washington Post’s weather blog, Capital Weather Gang. He and his crew verified what I found and wrote up their version, giving due credit and adding other evidence that something was very wrong at National. And, in remarkably quick action for a government agency, the National Weather Service swapped out the sensor within a week and found that the old one was reading 1.7 degrees too high. Close enough to 2.1, the observed difference.
But the National Weather Service told the Capital Weather Gang that there will be no corrections, despite the fact that the disparity suddenly began 19 months ago and varied little once it began. It said correcting for the error wouldn’t be “scientifically defensible.” Therefore, people can and will cite the May record as evidence for dreaded global warming with impunity. Only a few weather nerds will know the truth. Over a third of this year’s 37 90-degree-plus days, which gives us a remote chance of breaking the all time record, should also be eliminated, putting this summer rightly back into normal territory.
It is really politically unwise not to do a simple adjustment on these obviously-too-hot data. With all of the claims that federal science is being biased in service of the president’s global-warming agenda, the agency should bend over backwards to expunge erroneous record-high readings.
In July, by contrast, NOAA had no problem adjusting the global temperature history. In that case, the method they used guaranteed that a growing warming trend would substitute for “the pause.” They reported in Science that they had replaced the pause (which shows up in every analysis of satellite and weather balloon data) with a significant warming trend.
Normative science says a trend is “statistically significant” if there’s less than a 5 percent probability that it would happen by chance. NOAA claimed significance at the 10 percent level, something no graduate student could ever get away with. There were several other major problems with the paper. As Judy Curry, a noted climate scientist at Georgia Tech, wrote, “color me ‘unconvinced.’ ”
Unfortunately, following this with the kerfuffle over the Reagan temperature records is only going to “convince” even more people that our government is blowing hot air on global warming.
