Study: City heat can affect global climate

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BOULDER, Colo., Jan. 28 (UPI) -- Energy use in cities has global climate effects and urban heat can lead to continental-scale winter warming in high latitudes, U.S. researchers say.

Scientists at the National Center for Atmospheric Research in Boulder, Colo., and other research centers said heat generated by everyday energy consumption in metropolitan areas can influence the character of major atmospheric circulation systems, including the jet stream during winter months.

Waste heat released by major cities in the Northern Hemisphere can lead to as much as 1.8 degrees F of continental-scale winter warming in high latitudes of the North America and Eurasian continents, they said.

"The burning of fossil fuel not only emits greenhouse gases but also directly effects temperatures because of heat that escapes from sources like buildings and cars," NCAR researcher Aixue Hu said.

The influence of urban heat can widen the jet stream in areas outside the tropics, the researchers said.

"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 Guang Zhang, a research meteorologist at Scripps Institution of Oceanography at the University of California, San Diego.

The study has been published in the journal Nature Climate Change.