Summer of 2023 was the hottest in 2,000 years in some parts of the world, researchers say

Last summer's sweltering heat broke more than city or regional or even national records. In what they call an "alarming finding," scientists say that in the Northern Hemisphere, the summer of 2023 was the hottest in 2,000 years. 

Global data already showed that last summer was the hottest on record. Copernicus, the European Union's climate change observation organization, made that determination  But a new study, published in Nature on Tuesday, looked even further back using both observed and reconstructed temperatures from centuries past. 

They found the heat was "unparalleled," the researchers said.