More Frequent European Heat Waves Linked to Changes in Jet Stream

Heat waves over Europe have increased three to four times faster than in the rest of the northern mid-latitudes, including the United States and Canada. Why? In a new study, an international team of scientists has shown the increase is linked to changes in the jet stream, the fast air current that flows west to east about 10 kilometers above the surface of the Northern Hemisphere. Periods during which the jet stream is split into two branches—so called double jet states—have become longer. These double-jet states explain almost all of the upward trend in heat waves in western Europe, and around 30 percent over the larger European domain, say the authors. The study was just published in the journal Nature Communications.