Scientists explain why the record heat of 2023 has them nervous

The latest calculations from several scientific agencies showing that Earth obliterated global heat records last year may seem frightening. But scientists worry that what’s behind those numbers could be even worse.

The Associated Press news agency spoke to more than three dozen scientists about what the destroyed records mean. Most say they fear the acceleration of climate change, which is already just on the brink of the 1.5°C rise since pre-industrial times that nations hoped to stay within.

“The heat of the last calendar year was a dramatic message from Mother Nature,” says climatologist Katharine Jacobs of the University of Arizona. 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 especially bad.

The weather behaved strangely in 2023

Average global temperatures surpassed the previous record by just over 0.15°C, a huge margin, according to calculations released Friday by two major U.S. science agencies, the British weather service and a private group founded by a climate skeptic.

Several of the scientists who did the calculations said that the climate was behaving in strange ways in 2023. They wonder if man-made climate change and a natural El Niño phenomenon were exacerbated by a strange phenomenon or if “there is something more systematic going on,” 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. It was then that a strong the boy – the cyclical warming of Pacific Ocean waters that affects global weather patterns – is expected to disappear. If ocean temperatures, including deep water temperatures, continue to drop records Until well into the summer, like 2023, that would be an ominous clue, they say.

Nearly all scientists who responded to AP questions blamed greenhouse gases from burning fossil fuels as the overwhelmingly major reason why the world reached temperatures that human civilization had probably not seen before. El Niño, which borders on “very strong”, is the second most important factor, followed by other conditions, they say.

The problem with 2023, says NASA’s Schmidt, is that “it was a very strange year… The deeper you go into it, the less clear it seems.”

Part of that is the timing of the big heat explosion of 2023, according to Schmidt and Samantha Burgess, deputy director of Europe’s Copernicus Climate Service, which earlier this week estimated the warming at 1.48°C above pre-industrial times.

Temperatures are typically higher than normal in late winter and spring, they say. But the highest heat of 2023 came around June and remained at record levels for months.

Deep ocean heat, a major factor in global temperatures, behaved similarly, Burgess says.

A father tries to calm his daughter suffering from a heat-related illness at a hospital in Ballia, Uttar Pradesh state, India, June 2023.

A father tries to calm his daughter suffering from a heat-related illness at a hospital in Ballia, Uttar Pradesh state, India, June 2023. – AP Photo/Rajesh Kumar Singh, File

Is global warming accelerating faster than expected?

Former NASA climate scientist James Hansen, often considered the godfather of global warming science, theorized last year that heating I was accelerating. While many of the scientists contacted by the AP said they suspected this was happening, others insisted that the evidence so far only supports a long-predicted, steady rise.

“There is some evidence that the rate of warming over the last decade is slightly faster than the previous decade, which meets the mathematical definition of acceleration,” says UCLA climate scientist Daniel Swain. “However, this is also largely consistent with predictions” that warming speed up at a certain point, especially when airborne particle pollution decreases.

The United States National Oceanic and Atmospheric Administration (NOAA) estimated that the Earth in 2023 would have an average temperature of 15.08°C. That’s 0.15°C higher than the previous record set in 2016 and 1.35°C higher than pre-industrial temperatures.

“It’s almost like we jumped off the ladder. [of normal global warming temperature increases] toward a slightly warmer regime,” says Russ Vose, head of global monitoring at NOAA’s National Centers for Environmental Information. He says he sees an acceleration of warming.

NASA and the UK Met Office estimated the warming since the mid-19th century to be slightly greater, at 1.39°C and 1.46°C respectively. Records date back to 1850.

The World Meteorological Organization, combining measurements announced Friday with Japanese and European calculations released earlier this month, pegged 2023 at 1.45 degrees Celsius warmer than pre-industrial temperatures.

A woman protects herself from the sun with a hand-held fan in Madrid, Spain, on July 10, 2023.A woman protects herself from the sun with a hand-held fan in Madrid, Spain, on July 10, 2023.

A woman protects herself from the sun with a hand-held fan in Madrid, Spain, on July 10, 2023. – AP Photo/Manu Fernández, File

Is it still possible to reach a warming limit of 1.5°C?

Many climate scientists saw little hope of stopping warming in the future. 1.5 degree target required in the 2015 Paris agreement that sought to avoid the worst consequences of climate change.

“I do not consider it realistic that we can limit warming [averaged over several years] at 1.5°C,” says Jennifer Francis, a scientist at the Woodwell Climate Research Center. “It is technically possible but politically impossible.”

“The slowness of climate action and the continued misinformation that catalyzes it has never been due to a lack of science or even a lack of solutions: it has always been, and continues to be, due to a lack of information. political will” says Katharine Hayhoe, chief scientist at The Nature Conservancy.

Both NASA and NOAA said the last 10 years, from 2014 to 2023, have been the 10 hottest years they have measured. It is the third time in the last eight years that a global heat record has been set. Randall Cerveny, a scientist at Arizona State University who helps coordinate record-keeping for the WMO, says the big concern is not that a record was broken last year, but that they continue to be broken so frequently.

“For me, the most alarming thing is the rapidity of the continuous change,” Cerveny says.

Natalie Mahowald, a climate scientist at Cornell University, says: “This is just a taste of what we can expect in the future, especially if we continue not to reduce carbon dioxide fast enough.”

That’s why so many scientists contacted by The Associated Press are anxious.

“I’ve been worried since the early 1990s,” says Kim Cobb, a climate scientist at Brown University. “I am more worried than ever. “My concern grows with each passing year that global emissions are heading in the wrong direction.”

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