Last summer was the hottest in the Northern Hemisphere in at least 2,000 years, according to information gleaned by ancient tree rings.
According to a new study published this week in Nature, summer 2023 was not only 0.15 degrees Celsius hotter than the summer of 2016—which was previously the record-holder—but it was also 0.5 degree C hotter than the warmest summer that occurred in CE 246, a time before humans began burning fossil fuels and raising the global temperature.
Tree that grow in temperate regions can produce this data because the amount their rings grow each year is related to the seasonal temperatures around them. However, the study did have limitations: First, tropical trees don’t experience winter, so they don’t show the same annual rings, and second, the records of tree rings from the southern hemisphere are lacking. Therefore, the study was restricted to looking at the temperatures of the Northern Hemisphere between 30 and 90 degrees north latitude.
Study co-author Jan Esper, a dendrochronologist and climate scientist at Johannes Gutenberg University Mainz in Germany, said that 2023’s temperatures doesn’t necessarily mark a major increase in global warming, but rather that “it’s just a continuation of a trend.”
