Hot history: Tree rings show that last northern summer was the warmest since year 1

The broiling summer of 2023 was the hottest in the Northern Hemisphere in more than 2,000 years, a new study found. 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. 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. “The global temperature records set last summer were so gobsmacking — shattering the prior record by 0.5C in September and 0.4C in October — that it’s not surprising they would be clearly be the warmest in the past 2,000 years,” said Berkeley Earth climate scientist Zeke Hausfather, who wasn’t part of the study. “It’s likely the warmest summer in 120,000 years, though we cannot be absolutely sure,” he said, because data precise to a year doesn’t go back that far.