Megacities Alter Weather Across Long Distances, Study Says

Heat generated in major metropolitan areas is altering the character of the jet stream and other atmospheric systems, at times affecting the weather thousands of miles away, a new study says. Writing in the journal Nature Climate Change, a team of scientists reports that so-called “waste heat” produced from buildings, cars, and other sources is altering weather patterns and increasing winter temperatures across large areas of North America and northern Asia by as much as 1 degree C (1.8 degrees F). In parts of Europe, however, the changes to atmospheric circulation are causing temperatures to fall by as much as 1 degree C., the study found. “Although much of this waste heat is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances,” said Aixue Hu, a scientist at the National Center for Atmospheric Research and one of the lead authors of the study. According to the study, this phenomenon is different than the so-called “heat island effect,” in which cities are warmer than surrounding areas as a result of heat collected and re-radiated by pavement, buildings, and other urban features.