The new American standard: a degree warmer than two decades ago
Scientists have long talked about climate change – warmer temperatures, changes in rain and snow, and more extreme weather – being the “new normal”. Data released Tuesday by the National Oceanic and Atmospheric Administration put concrete numbers on the picture.
The new normal in the United States is not only warmer, but more humid in the east and center of the country and considerably drier in the West than a decade earlier.
Meteorologists calculate climate normals based on 30 years of data to limit random fluctuations in daily weather. It is a standard set by the World Meteorological Organization. Every 10 years, NOAA updates the standard for the country as a whole, states, and cities – by year, month, and season.
For the whole country, the normal annual temperature is now 53.3 degrees (11.8 degrees Celsius) based on weather station data from 1991 to 2020, almost half a degree higher than ten years ago. Twenty years ago, the normal was 52.3 degrees (11.3 degrees Celsius) based on data from 1971 to 2000. The average temperature in the United States for the 20th century was 52 degrees (11.1 degrees Celsius).
The new annual normal temperature in the United States is 1.7 degrees (0.9 Celsius) warmer than the first normal calculated for 1901 to 1930.
“Almost every location in the United States has gone from normal from 1981 to 2010 to normal from 1991 to 2020,” said Michael Palecki, NOAA’s standards project manager.
Fargo, North Dakota, where the new normal is a tenth of a degree cooler than the old one, is an exception, but over 90% of the United States has warmer normal temperatures than 10 years ago , Palecki said.
In Chicago and Asheville, North Carolina, the new normal annual temperature has jumped 1.5 degrees in a decade. Seattle, Atlanta, Boston, and Phoenix have experienced a normal annual increase in temperature of at least half a degree over the past decade.
Charlottesville, Virginia experienced the largest increase in normal temperatures among 739 major weather stations. Other significant changes have taken place in California, Texas, Virginia, Indiana, Arizona, Oregon, Arkansas, Maryland, Florida, North Carolina and Alaska.
The normal news is warmer because the burning of fossil fuels has made the past decade “a much hotter period for much of the globe than previous decades,” said Natalie Mahowald, climatologist at Cornell University.
For Phoenix, the biggest change from normal came in precipitation. Normal annual precipitation for Phoenix has dropped 10% to 7.2 inches (18.2 centimeters). Rainfall in Los Angeles fell 4.6%.
At the same time, Asheville experienced an almost 9% increase in precipitation, while precipitation in New York City increased by 6%. Seattle normal is 5% wetter than before.
Climatologists are divided on the usefulness or confusion of the new calculated normals.
Mahowald and University of Oklahoma meteorology professor Jason Furtado said updating normal calculations helps city planners and area planners prepare for floods and drought, farmers decide what and when to plant, energy companies to meet changing demand and doctors to tackle climate-related public health issues. change.
But Pennsylvania State University climate scientist Michael Mann said he prefers a constant baseline such as 1951 to 1980, which NASA uses. Adjusting normal every 10 years “perverts the meaning of ‘normal’ and ‘normalizes’ climate change,” he said in an email.
North Carolina state climatologist Kathie Dello said: “It seems strange to still call them normal because 1991-2020 was anything but climate-normal.”
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