The latest calculations from several science agencies showing Earth obliterated global heat records last year may seem scary. But scientists worry that what’s behind those numbers could be even worse.
The Associated Press asked more than three dozen scientists in interviews and emails what the smashed records mean. Most said they fear acceleration of climate change that is already right at the edge of the 1.5 degrees Celsius (2.7 Fahrenheit) increase since pre-industrial times that nations had hoped to stay within.
“The heat over the last calendar year was a dramatic message from Mother Nature,” said University of Arizona climate scientist Katharine Jacobs. Scientists say warming air and water is making deadly and costly heat waves, floods, droughts, storms and wildfires more intense and more likely.
This last year was a doozy.
Average global temperatures broke the previous record by 0.15 degrees Celsius, a big margin, according to calculations Friday from two top American science agencies, the British meteorological service and a private group founded by a climate skeptic.
Several of the scientists who made the calculations said the climate behaved in strange ways in 2023. They wonder whether human-caused climate change and a natural El Nino were augmented by a freak blip or whether “there’s something more systematic afoot,” as NASA climate scientist Gavin Schmidt put it — including a much-debated acceleration of warming.
A partial answer may not come until late spring or early summer. That’s when a strong El Nino — the cyclical warming of Pacific Ocean waters that affects global weather patterns — is expected to fade away. If ocean temperatures, including deep waters, keep setting records well into the summer, like in 2023, that would be an ominous clue, they say.
Nearly every scientist who responded to AP’s questions blamed greenhouse gases from the burning of fossil fuels as the overwhelmingly largest reason the world hit temperatures that human civilization has not likely seen before. El Nino, which is bordering on “very strong,” is the second-biggest factor, with other conditions far behind, they said.
The trouble with 2023, NASA’s Schmidt said, is “it was a very strange year … The more you dig into it, the less clear it seems.”
One part of that is the timing for when 2023’s big burst of heat began, according to Schmidt and Samantha Burgess, deputy director of Europe’s Copernicus Climate Service, which earlier this week put warming at 1.48 degrees Celsius above pre-industrial times.
Temperatures are typically highest above normal in late winter and spring, they said. But 2023’s highest heat kicked in around June and lingered at record levels for months.
Former NASA climate scientist James Hansen, often considered the godfather of global warming science, theorized last year that warming was accelerating. While many of the scientists contacted by AP said they suspect it is happening, others were adamant that evidence so far supports only a steady and long-predicted increase.
“There is some evidence that the rate of warming over the past decade or so is slightly faster than the decade or so previous — which meets the mathematical definition of acceleration,” said UCLA climate scientist Daniel Swain. “However, this too is largely in line with predictions” that warming would accelerate at a certain point, especially when particle pollution in the air decreases.
The U.S. National Oceanic and Atmospheric Administration calculated that Earth in 2023 had an average temperature of 59.12 degrees (15.08 degrees Celsius). That’s 0.27 degrees (0.15 degrees Celsius) warmer than the previous record set in 2016 and 2.43 degrees (1.35 degrees Celsius) warmer than pre-industrial temperatures.
“It’s almost as if we popped ourselves off the staircase (of normal global warming temperature increases) onto a slightly warmer regime,” said Russ Vose, global monitoring chief for NOAA’s National Centers for Environmental Information. He said he sees acceleration of warming.
Many of the scientists saw little hope of stopping warming at the 1.5-degree goal called for in the 2015 Paris agreement that sought to avert the worst consequences of climate change.
“It is technically possible but politically impossible,” Woodwell Climate Research Center scientist Jennifer Francis wrote in an email.
