Urban Heat Has Large-scale Climate Effects

The heat generated by everyday activities in metropolitan areas has a significant enough warming effect to influence the character of the jet stream and other major atmospheric systems during winter months, according to a trio of climate researchers. Led by Guang Zhang, a research meteorologist at Scripps Institution of Oceanography, UC San Diego, the scientists report Climate Change that the extra heat given off by Northern Hemisphere urban areas causes as much as 1 degree C (1.8 degrees F) of warming in winter. They added that this effect helps explain the disparity between actual observed warming in the last half-century and the amount of warming that computer models have been able to account for. "What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions," said Zhang. "This is accomplished through atmospheric circulation change." The study, "Energy consumption and the unexplained winter warming over northern Asia and North America," appears in online editions of the journal Jan. The National Science Foundation, the U.S. Department of Energy, and NOAA supported the research. Zhang, along with Ming Cai of Florida State University and Aixue Hu of the National Center for Atmospheric Research in Boulder, Colo., considered the energy consumption - from heating buildings to powering vehicles - that generates waste heat release.