Weather’s New Normal Reveals ‘Fingerprints of Climate Change’

Source: By Brian K Sullivan, Bloomberg • Posted: Wednesday, April 21, 2021

The U.S. is about to officially establish a new normal for its weather, and it has the “fingerprints of climate change” all over it.

Every decade, the U.S. reconfigures what’s considered to be normal temperatures and normal rain and snow across the country. As of May 4, the averages from 1991 to 2020 will replace the current set based on 1981 to 2010. When compared with the entire 20th century average, the results are stark: The U.S. is a warmer and wetter place than it was almost a century ago.

“Climate change is clearly seen in these new normals,” said Michael Palecki, normal project manager at the U.S. National Centers for Environmental Information. “We’re really seeing the fingerprints of climate change in the new normals.”

Aside from giving scientists measure of how much the U.S. is changing, the normals are commonly used by natural gas and commodity traders to bid on contracts for energy usage, as well as potential yields for a variety of crops including corn and soybeans.

The public most often encounters these values when a TV meteorologist explains how much warmer or cooler a particular day was. For instance, in a recent cold spell across Texas, temperatures in Dallas-Fort Worth had dropped 42 degrees Fahrenheit (23 Celsius) below normal on Feb. 16.

“What we are trying to do is put today’s weather in a proper context,” Palecki said. “To understand today’s climate, so people know what to expect.”

That includes rain and snow data compiled from 15,000 stations, while the temperature readings come from 7,300 locations across the U.S. The numbers are then checked to see if there were any changes in time of day or location.

While compared to the 20th century average there is a stark change, when 1991 to 2020 is compared with 1981 to 2010 there is actually a pocket in the northern Great Plains that has got cooler overall. For instance the average annual temperature in Fargo, North Dakota, has dropped 0.1 of a degree to 42.3 and the city now has more rain.

Data from around the world will also be updated. Earlier this month, the average number of named storms in the Atlantic was increased to 14 up from 12.