Jet Stream Affected By Big City Waste Heat
January 28, 2013

Big Cities Could Alter Weather Of Areas Over 1,000 Miles Away

redOrbit Staff & Wire Reports - Your Universe Online

Large metropolitan areas could be drastically impacting the weather where you live, even if they´re hundreds of miles away, researchers from the Scripps Institution of Oceanography (SIO); the University of California, San Diego (UCSD); Florida State University (FSU); and the National Center for Atmospheric Research (NCAR) claim in a new study.

The researchers, who report their findings in the journal Nature Climate Change, discovered that the heat generated by day-to-day human activities in large cities can affect the jet stream and other major atmospheric systems.

Furthermore, these affects can cause warming or cooling to occur in areas more than 1,000 miles away.

“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,” the NCAR explained Sunday in a statement.

The research organization added that temperatures in some areas could increase by as much as 1.8-degrees Fahrenheit, while in Europe, similar changes to atmospheric circulation caused by waste heat lead to a 1.8-degree Fahrenheit decrease in temperature, especially during the autumn months.

“The net effect on global mean temperatures is nearly negligible–an average increase worldwide of just 0.01 degrees C (about 0.02 degrees F). This is because the total human-produced waste heat is only about 0.3 percent of the heat transported across higher latitudes by atmospheric and oceanic circulations,” the NCAR said. “However, the noticeable impact on regional temperatures may explain why some regions are experiencing more winter warming than projected by climate computer models.”

"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," added Aixue Hu, co-author of the study and a researcher at the Boulder, Colorado-based research center. "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."

The researchers, whose work was funded by the National Science Foundation (NSF), the US Department of Energy, and the National Oceanic and Atmospheric Administration (NOAA), explain that the waste-heat effect discussed in their study is different than the phenomenon known as the urban heat island effect.

While the impact on islands is typically caused by heat that is “collected and re-radiated by pavement, buildings, and other urban features,” the heat discussed in the new study focuses on heat that is “produced directly through transportation, heating and cooling units, and other activities,” the NCAR statement explained. Their findings were based upon an analysis of energy consumption resulting in the release of waste heat.

“The world's total energy consumption in 2006 was equivalent to a constant-use rate of 16 terawatts (one terawatt, or TW, equals 1 trillion watts). Of that, an average rate of 6.7 TW was consumed in 86 metropolitan areas in the Northern Hemisphere,” the researchers said.

They discovered, through the use of computer-based atmospheric modeling, that this waste heat can actually cause the jet stream to become wider, altering circulation patterns and impacting places up to thousands of miles away from the region where the energy consumption actually takes place.

"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," FSU researcher Dr. Ming Cai said.

"The release of this concentrated waste energy causes the noticeable interruption to the normal atmospheric circulation systems above, leading to remote surface temperature changes far away from the regions where waste heat is generated,” he added.