The U.S. National Oceanic and Atmospheric Administration (NOAA) revealed new standards on Tuesday, May 4, 2021 for what an average or “normal” U.S. climate looks like, showing average temperatures in the U.S. rising significantly.
Shifting the baseline for normal temperatures highlights just how quickly climate crisis is affecting conditions on Earth.
Updating these standards is important for helping shape government policies and what local weather forecaster says the “average” high temperature is on a given date.
NOAA releases climate averages for the preceding 30-year period every 10 years. The “climate normals” cover 1991-2020 and indicate that the U.S. climate has warmed, and also become wetter over time.
NOAA noted that parts of the U.S. may also get drier, due to climate change.
“The influence of long-term global warming is obvious,” per a press release.
The new normals may shift how the climate is described for particular parts of the U.S.
(Source: U.S.NCEI)
With the changes, Fairbanks, Alaska is no longer considered a sub-Arctic climate, but is now termed a “warm summer continental” climate.
The new normals show how the U.S. is getting warmer and, overall, wetter as climate change continues. There are some exceptions to the rule, though, with warming especially pronounced in the Northeast and West, and rainfall coming in shorter, heavier bursts. The West has become drier with time, too.
U.S.’s new normal temperature is a degree hotter than it was just two decades ago.
Data released by the NOAA put hard figures on the cliché.
For the entire U.S., the yearly normal temperature is now 53.3 degrees (11.8 degrees Celsius) based on weather station data from 1991 to 2020, nearly half a degree warmer than a decade ago. Twenty years ago, normal was 52.3 degrees (11.3 degrees Celsius) based on data from 1971 to 2000. The average U.S. temperature for the 20th century was 52 degrees (11.1 degrees Celsius).
The new normal annual U.S. temperature is 1.7 degrees (0.9 Celsius) hotter than the first normal calculated for 1901 to 1930.
“Almost every place in the U.S. has warmed from the 1981 to 2010 normal to the 1991 to 2020 normal,” said Michael Palecki, NOAA’s normals project manager.
Fargo, North Dakota, where the new normal is a tenth of a degree cooler than the old one, is an exception, but more than 90% of the U.S. has warmer normal temperatures now than 10 years ago, Palecki said.
In Chicago and Asheville, North Carolina, the new yearly normal temperature jumped 1.5 degrees in a decade. Seattle, Atlanta, Boston and Phoenix had their normal annual temperature rise by at least half a degree in the last decade.
Charlottesville, Virginia, saw the biggest jump in normal temperatures among 739 major weather stations. Other large changes were in California, Texas, Virginia, Indiana, Arizona, Oregon, Arkansas, Maryland, Florida, North Carolina and Alaska.
New normals are warmer because the burning of fossil fuels is making the last decade “a much hotter time period for much of the globe than the decades” before, said Cornell University climate scientist Natalie Mahowald.
For Phoenix, the biggest change in normal came in precipitation. The normal annual rainfall for Phoenix dropped 10% down to 7.2 inches (18.2 centimeters). Rainfall in Los Angeles dropped 4.6%.
At the same time, Asheville saw a nearly 9% increase in rainfall, while New York City’s rainfall rose 6%. Seattle’s normal is 5% wetter than it used to be.
Climate scientists are split about how useful or misleading newly calculated normals are.
Mahowald and University of Oklahoma meteorology professor Jason Furtado said updating normal calculations helps city and regional planners to prepare for flooding and drought, farmers to decide what and when to plant, energy companies to meet changing demands and doctors to tackle public health issues arising from climate change.
But Pennsylvania State University climate scientist Michael Mann said he prefers a constant baseline such as 1951 to 1980, which is what NASA uses. Adjusting normal every 10 years “perverts the meaning of ‘normal’ and ‘normalizes’ away climate change,” he said in an email.
North Carolina’s state climatologist Kathie Dello said, “It seems odd to still call them normals because 1991-2020 was anything but normal climate-wise.”
(Source: U.S.NCEI)
Precipitation – regardless of human-caused climate change – varies a lot from place to place across the U.S., NOAA said.
As noted by the Capital Weather Gang, there are signs that a multi-decade megadrought may have already set in over the southwest U.S.
The first time normals were calculated was for the period covering 1901-1930, and at that time it was measured by the World Meteorological Organization. The U.S. eventually adopted the same 30-year system.
The normals for the past decade, with data spanning from 1991 to 2020, were released by the NOAA’s National Climatic Data Center (NCDC). The last report that was released measured normals from the 1981 to 2010 period. While it is referred to as a report, it is actually a data set that people can refer back to when needed, although the NOAA also has created some explanatory web pages to help people navigate the data.
“As the Southwest gets even drier, there is less moisture to evaporate, which allows more of the sun’s energy to go directly into heating the surface, which also helps to explain the rapid warming in this region,” AccuWeather Senior Meteorologist Brett Anderson wrote in a recent blog post on the topic.
“Tracking weather normals allows meteorologists to put today’s (or this year’s) weather into context versus recent history, to detect trends and rate the rarity of current weather events versus history,” AccuWeather Senior Weather Editor Jesse Ferrell said.
In addition to the weather community, many other industries that are not directly tied to meteorology look to weather normals as well.
According to the NCEI, (National Centers for Environmental Information) April is the most “dynamic” core month, core months being those in the middle of a season (January, April, July and October).
Changes in temperature normals were as much as 2 degrees Fahrenheit lower in the Dakotas in April when compared to the prior decade, while regions both west and east of the Mississippi Valley continued to see a warming trend.
The transportation sector is currently the largest source of emissions, and large-scale electric transportation could be a solution to cut those down in the nation. The energy sector is the second-biggest source of emissions in the U.S., and things like wind and solar-powered energy can help to curb those emissions too.
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