'City heat affects temperatures 1,000 miles away'
The heat generated by cities could affect temperatures a thousand miles away, warming some areas and cooling others, says an American study.
The extra "waste heat" generated from buildings, cars, and other sources in major Northern Hemisphere urban areas causes winter warming across large areas of northern North American and northern Asia.
Temperatures in some remote areas increase by as much as one degree Celsius, according to scientists from the Scripps Institution of Oceanography, University of California-San Diego, Florida State University, and the National Centre for Atmospheric Research (NCAR), the journal Nature Climate Change reports.
At the same time, the changes to atmospheric circulation caused by the waste heat cool areas of Europe by as much as one degree, with much of the temperature decrease occurring in the fall, according to a Scripps statement.
The noticeable impact on regional temperatures may explain why some regions are experiencing more winter warming than projected by climate computer models, the researchers conclude.
"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," says study co-author Aixue Hu, NCAR scientist.
"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," adds Hu.
Hu, along with Guang Zhang of Scripps and Ming Cai of Florida State University, analysed the energy consumption - from heating buildings to powering vehicles - that generates waste heat release.
"The world's most populated and energy-intensive metropolitan areas are along the east and west coasts of the North American and Eurasian continents, underneath the most prominent atmospheric circulation troughs and ridges," Cai says.