Researchers already knew that 2023 was one for the books, with average temperatures soaring past anything recorded since 1850. But there are no measurements stretching further back than that date, and even the available data is patchy, according to a study published Tuesday in the journal Nature. So, to determine whether 2023 was an exceptionally hot year relative to the millennia that preceded it, the study authors turned to records kept by nature.
Temperatures recorded during the summer of 2023 exceeded those of the coldest summer in the past 2,000 years, in A.D. 536, by 7 degrees Fahrenheit . That relatively cool summer followed a volcanic eruption that dumped huge amounts of sunlight-blocking sulfur particles into the stratosphere, which triggered global cooling, according to the study.
Sign up for the Live Science daily newsletter nowGet the world’s most fascinating discoveries delivered straight to your inbox. "It's true that the climate is always changing, but the warming in 2023, caused by greenhouse gases, is additionally amplified by El Niño conditions," lead author Jan Esper, a professor of climate geography at the Johannes Gutenberg University Mainz in Germany, said in the statement.