The weather normals are out, and it’s no surprise that Athens is warming up. What’s surprising is the acceleration – how quickly the city and state are heating up.
Every 10 years, the National Oceanic and Atmospheric Administration recalculates a new set of these normals for nation, state, and individual weather stations across the United States, including the official Athens recording station at the Athens Ben-Epps Airport. Normals are a 30-year average – from 1991 to 2020 in the latest round of 2020 – of measurements such as daily maximum, minimum, and overall average temperatures by day, month, and year. The normals also include the averages for rain and snow.
Now, the “normal” average annual temperature in Athens is 62.6 degrees, according to a database built by the High Plains Regional Climate Center at the University of Nebraska. This is almost a degree warmer than the 2010 normal in Athens and 1.4 degrees warmer than the 1990 normal.
After rising sharply during the first decades of the 20th century, average temperatures actually declined in Athens, Georgia, and the United States in the mid-20th century. We do not know why. The trough was once thought to be the effect of mid-century reforestation, as millions of acres of depleted farmland and exploited mountainsides and swamps regenerated as best they could. Calculations do not support this theory, however, according to University of Georgia engineering professor David Stooksbury, the former Georgia state climatologist.
Since that brief cooling, however, temperatures have risen at an accelerating rate in Athens, as in the rest of the world. The mean normal temperature for 2000 (years 1971-2000) was 0.3 degrees higher than the 1990 normal. In 2010, the normal increased another 0.3 degrees to 61.8, according to the database. Nebraska. The latest 30-year normal once again pushes the annual mean almost a full degree to 62.6, and most of that increase has only occurred in the last decade. The average annual temperature in Athens rose slightly by 0.1 degrees in the 1990s, jumped a further 0.6 degrees in the 2000s, and then climbed 1.4 degrees to 63.7 in the 2010s. thermometer at the airport topped 90 for a record 54 consecutive days in 2016, the hottest year on record for Athens.
Climatologists are also seeing an alarming acceleration in other measures of induced climate change, such as the constant shrinking of the Arctic sea ice. The pace of climate change that’s happening now looks a lot like what climate change scientists projected as the worst-case scenarios not too long ago. “It’s like that,” said Pam Knox, UGA agricultural climatologist, when asked if climate change is accelerating.
Athens is far from the only one experiencing a rapid rise in temperatures. “In Florida, the last decade just hit the charts,” Knox said.
Atlanta and other cities in Georgia are also getting warmer, in similar patterns to Athens. Atlanta’s new normal average temperature is now 63.7 degrees, up 1.8 degrees from 1990 normal. The 2010s in Hotlanta were 2.6 degrees warmer than the 1990 normal average.
Savannah, which also faces accelerating sea level rise due to global warming, has been 2.7 degrees warmer in the past decade than 1990 normal, according to base figures High Plains data. Models predict that sea level will rise 10 feet or more, even if carbon emissions stop immediately. The scientific debate is now more about whether this will happen in the next decades or in the next two centuries.
In Athens and other cities, winter temperatures have changed the most. The normal January temperature in Athens is now 2.7 degrees warmer than in 1990, and February is up 2.5 degrees. Over the past decade, Athens has averaged 49.1 degrees in December, almost 5 degrees higher than the December 1990 normal.
It’s not just the numbers that are changing now, but the very meaning of climate normals, said Knox, a former Wisconsin state climatologist and deputy state climatologist in Georgia. “The normals were designed in the hope that the climate would be stable,” she said. But with the rapid increase in warming, these normals are no longer the reliable tool they were for farmers and others when the first norms were released in 1931.
The average precipitation of Athens changed only slightly in the news normal; 48.95 inches per year, up from the 2010 normal of 46.33 inches. In recent decades, precipitation has increased significantly in the northeast and decreased sharply in the west, but averaged about the same in the southeast. But there is growing evidence that precipitation patterns, if not the averages, change as people pump more carbon into the atmosphere, Stooksbury said. The rain comes in more intense gusts, with longer dry spells in between, like last month in Athens. Athens received 3.86 inches of rain over four days in early May, followed by 15 days with no rain at all. Georgia and the Southeast also tend to be drier in the fall, according to NOAA statistics.
Meanwhile, the rising temperature trend continues. So far this year, Athens has been almost 2 degrees above normal, which is 2 degrees above the new normal.
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