Here we combine observed and reconstructed June–August surface air temperatures to show that 2023 was the warmest Northern Hemisphere extra-tropical summer over the past 2,000 years exceeding the 95% confidence range of natural climate variability by more than 0.5 °C. Comparison of the 2023 June–August warming against the coldest reconstructed summer in ce 536 shows a maximum range of pre-Anthropocene-to-2023 temperatures of 3.93 °C. Although 2023 is consistent with a greenhouse-gases-induced warming trend7 that is amplified by an unfolding El Niño event8, this extreme emphasizes the urgency to implement international agreements for carbon emission reduction.
Tree ring study proves current temps hottest in over 2000 years
The broiling summer of 2023 was the hottest in the Northern Hemisphere in more than 2,000 years, a new study found.
When the temperatures spiked last year, numerous weather agencies said it was the hottest month, summer and year on record. But those records only go back to 1850 at best because it’s based on thermometers. Now scientists can go back to the modern western calendar’s year 1, when the Bible says Jesus of Nazareth walked the Earth, but have found no hotter northern summer than last year’s.
A study Tuesday in the journal Nature uses a well-established method and record of more than 10,000 tree rings to calculate summertime temperatures for each year since the year 1. No year came even close to last summer’s high heat, said lead author Jan Esper, a climate geographer at the Gutenberg Research College in Germany.
Before humans started pumping heat-trapping gases into the atmosphere by burning coal, oil and natural gas, the hottest year was the year 246, Esper said. That was the beginning of the medieval period of history, when Roman Emperor Philip the Arab fought Germans along the Danube River.
Esper’s paper showed that in the Northern Hemisphere, the summer of 2023 was as much as 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 that early medieval summer, said study co-author Max Torbenson.
“That gives us a good idea of how extreme 2023 is,” Esper told The Associated Press.\
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