Study reveals north–south differences in water isotopes across North America during the last deglaciation

The last deglaciation (between 11,000 and 20,000 years ago) was a period of dramatic natural warming on Earth. During this time, North America experienced the most extensive ice-sheet melting on the planet, which profoundly reshaped its climate and water cycle. But when scientists look at oxygen isotopes in stalagmites—a key tool for reconstructing past climate—the signals from North America have been hard to interpret. A new study now provides a physical explanation for those puzzling patterns.