Urban Heat May Warm Faraway Places – National Geographic


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Urban Heat May Warm Faraway Places – National Geographic

  1. 1. Urban Heat May Warm Faraway Places – NationalGeographicThe massive amounts of heat produced by cities may be heating up rural areas 1,000miles (1,600 kilometers) away, atmospheric researchers have found in a new modelingstudy.Scientists have long invoked the “urban island heat effect” to explain why cities are generallyhotter than suburban and rural areas. More people, as well as more cars, houses, and pavedsurfaces, turn energy into heat, which is radiated into the atmosphere.But new modeling research from the Scripps Institution of Oceanography at the University ofCalifornia, San Diego, suggests that cities in the Northern Hemisphere can also increase theheat of faraway rural places up to 1.8ºF (1°C)—a substantial aggregate increase.The reason comes down to global air flow.Heat produced by cars and people travels about 2,500 feet (4,023 kilometers) into theatmosphere, where it disturbs part of the jet stream that continually circulates a belt of cool airaround the top of the planet. When hot air intercepts the jet stream, it pushes the belt upward,allowing warmer air from the Equator to come farther north, warming parts of northern Europeand North America that normally would have been cooler.Over the Northern Hemisphere, 86 major metropolitan areas cover only 1.27 percent of theEarth’s surface. But those areas consume 6.7 terawatts of energy annually—representing 42percent of annual global consumption.Those cities’ influence on global climate is therefore magnified, according to the study,published Sunday in the journal Nature Climate Change.Until now, climate researchers have mostly pointed to greenhouse gasses as the sole cause ofclimate change. But the planet has been warming in some areas faster than models havepredicted.The impacts of urban heat produced by energy consumption may account for some of that extrawarming, said Guang Zhang, a meteorologist at Scripps who conducted the study: “Essentially,we are now able to account for a missing part of the warming.”Zhang found that the areas most significantly impacted by this urban heat effect were Siberiaand northern Canada, which can see temperatures rise 1.4º to 1.8°F (0.8° to 1°C) due tourban heat in faraway cities like New York or San Francisco.Further south, areas like Minnesota and Michigan might see a 0.5°F (0.3°C) increase. Themodeling was conducted with data from the National Center for Atmospheric Research, aleading source of global climate data. 1/2
  2. 2. While it’s true that the Earth’s aggregate climate affects every spot on the planet, the impacts of city heat were most pronounced in the Northern Hemisphere, where nearly 90 percent of the global population lives. And the most dramatic cool usually comes in the fall, the researchers said, for reasons that can’t yet be fully explained. Source Article from http://news.nationalgeographic.com/news/2013/130128-climate-cities-urban-heat-island-atmosp here-science/ Waddywood.com Urban Heat May Warm Faraway Places – National Geographic 2/2Powered by TCPDF (www.tcpdf.org)