The scorching summer of 2023 was the hottest in the Northern Hemisphere in more than 2,000 years, according to a new study.
When temperatures soared last year, multiple weather agencies said it was the hottest month, summer and year on record. But these records date back to 1850 at best because they are based on thermometers. Now scientists can go back to the 1st year of the modern western calendar that the Bible says. Jesus Christ We’ve traveled around the world, but we’ve never encountered a warmer northern summer than last year’s.
A study published Tuesday in the journal Nature uses a well-established method and records of more than 10,000 tree rings to calculate summer temperatures for every year since Year 1. No year has come close to last summer’s high temperature, said lead author Jan Esper, a climate geographer at the Gutenberg Research College in Germany.
Esper said the hottest year before humans started pumping heat-trapping gases into the atmosphere by burning coal, oil and natural gas was 246. This was the beginning of the period of medieval history in which the Roman Emperor Philip the Arab fought the Germans along the Danube.
Esper’s paper showed that the summer of 2023 in the Northern Hemisphere is 2.1 degrees Fahrenheit (1.2 degrees Celsius) warmer than the summer of 246. In fact, 25 of the last 28 years have been hotter than the summer of the early Middle Ages. Check out co-author Max Torbenson.
“This gives us a good idea of how extreme a year 2023 is going to be,” Esper told The Associated Press.
Esper said the team used thousands of trees in 15 different locations north of the tropics in the Northern Hemisphere, where there was enough data to get a good number by year 1. He said there wasn’t enough tree data to be published in the Southern Hemisphere, but sparse data showed something similar.
Scientists look at annual tree growth rings and “we can match them up almost like a retroactive puzzle, so we can assign annual dates to each ring,” Torbenson said.
Why stop looking at year 1 when other temperature reconstructions go back more than 20,000 years, asked University of Pennsylvania climate scientist Michael Mann, who was not part of the study but published the famous hockey stick chart more than a quarter-century ago? It shows rising temperatures since the Industrial Age. Relying solely on tree rings is “significantly less reliable” than looking at any kind of representative data, including ice cores, corals and more, he said.
Esper said his new study used only tree data because that data is precise enough to give temperature estimates from summer to summer, something that can’t be done with corals, ice cores and other proxy objects. He said tree rings have higher resolution.
“Global temperature records set last summer were so jaw-dropping that they shattered previous records of 0.5°C in September and 0.4°C in October, clearly the warmest in 2000 years,” said Berkeley Earth climate scientist. “It’s not surprising,” he said. Zeke Hausfather, who was not part of the research. “It’s probably the hottest summer in the last 120,000 years, but we can’t be exactly sure,” he said, because precise data for a year doesn’t go back that far.
Because high-resolution annual data don’t go back that far, Esper said scientists and the media were wrong to call this the hottest event in 120,000 years. “Two thousand years is enough,” he said.
Esper also said the pre-industrial period between 1850 and 1900, which scientists, particularly the Intergovernmental Panel on Climate Change, use for the baseline period before warming, may have been slightly colder than instrumental records indicate. At that time, the tools were more in the hot sun rather than protected as they are now, and tree rings continue to show that the temperature was about 0.4 degrees (0.2 degrees Celsius) cooler than thermometers indicated.
This means that warming from human-caused climate change is slightly greater than most scientists calculate; This is a topic that researchers have been focusing on for the last few years.
Looking specifically at the temperature records of the last 150 years, Esper noticed that while it was increasing in general, this increase occurred first with slow increases and then with giant steps, just like last year. These steps are often associated with a natural El Niño that occurs in the central Pacific, changing weather around the world and adding even more heat to a changing climate, he said.
“I don’t know when the next step will be taken, but I wouldn’t be surprised by another big step in the next 10-15 years, that’s for sure,” Esper said at a news conference. “And that’s very worrying.”
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