Heat generated through everyday activities in one urban setting can affect the jet stream and other atmospheric systems, according to a new study in which the National Center for Atmospheric Research was a participant.
Extra "waste heat," as it is termed in the study, generated by buildings, cars and other sources in major Northern Hemisphere urban centers can cause winter warming across large areas of North America and northern Asia, researchers found.
However, the study shows, changes to atmospheric circulation caused by waste heat also cools areas of Europe by as much as 1.8 degrees Fahrenheit, with much of that cooling coming in the fall.
The net effect on global mean temperatures is almost negligible, amounting to an average increase of just about 0.02 degrees Fahrenheit. That is because the total waste heat attributed to humans' activity represents only about 0.3 percent of the heat that is transported across high latitudes through oceanic and atmospheric circulations.
"The burning of fossil fuel not only emits greenhouse gases but also directly affects temperatures because of heat that escapes from sources like buildings and cars," NCAR scientist Aixue Hu, a co-author of the study, said in a news release. "Although much of this waste is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances."
The study, also including the work of scientists at the Scripps Institution of Oceanography, the University of California at San Diego, Florida State University, appears today in the journal Nature Climate Change. ___