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2023 was the second-warmest year on record in St. Louis. Here’s what that means

Climate experts predict rising summer temperatures increasing, with a sharp spike around the middle of the century.
Yunyi Dai
Special to The Midwest Newsroom
Climate experts predict summer temperatures will increase, with a sharp spike around the middle of the century.

Updated at 10:50 a.m. Jan. 11 with Missouri's final ranking

St. Louis experienced its second-warmest year on record in 2023, according to the National Weather Service. While the city didn’t quite break the record set in 2012, worldwide temperatures did.

Last year was also hot statewide in both Missouri and Illinois. Missouri tied for the third-warmest year on record, while Illinois had its fifth-warmest year. Both outpaced what state climatologists expected thanks to an unusually warm December. In fact, Illinois State Climatologist Trent Ford said warmer winters drove the record-setting heat, rather than heat in the summer.


“The largest departure from normal temperatures in 2023 was actually the coldest months,” Ford said. “So January, February and December were all at least 5 degrees above normal.”

Local temperatures are an important measure of how individuals experience a changing climate, but the global broken record is especially significant. Last year was the hottest in records that go back about 150 years, but it was also likely the hottest in more than 100,000 years, said Michael Wysession, a professor of Geophysics in the Department of Earth, Environmental and Planetary Sciences at Washington University.

There were multiple factors that led to the record-breaking year, Wysession said. The El Niño weather pattern is especially instrumental in bringing warm temperatures, as well as solar cycles and even an underwater volcano eruption in the Pacific Ocean. But humanity’s carbon emissions are creating a rising baseline of heat.

“Before there were humans, there's weather and climate, there were warm years and cold years, there were ocean currents, and the sun was hot and cold,” Wysession said. “We're still going to see these fluctuations. That's now on top of an increasing rate of fossil fuel carbon dioxide gas released.”

The worldwide average temperature was 1.48 degrees Celsius above pre-industrial levels, according to Copernicus. That’s close to the 1.5-degree limit set out in the Paris Climate Agreement. Wysession said while there’s nothing magic about that number, it does mean the world is approaching the danger zone for potential climate “tipping points,” including ice sheet collapse and permafrost thaw. But there is still room for hope.

“We can take action, and the greenhouse gas levels will drop, and we can cause this increase in temperature to reverse,” Wysession said. "We had the technology to make this happen in the first place, we have the technologies to reverse it. It's a political challenge, not a technological one.”

Kate Grumke covers the environment, climate and agriculture for St. Louis Public Radio and Harvest Public Media.