Waste Heat from Large Cities Altering Temperature for Thousands of Miles: Study

Ever wondered what would be the effect of the everyday activities occurring in major cities? Do we ponder on the extra waste heat that we generate from cars, chimneys and other sources? Apart from producing carbon dioxide that is the primary greenhouse gas, this waste heat, which is emitted directly into the atmosphere, plays a very crucial role in influencing the temperatures thousands of miles away.

According to a recent study conducted by scientists at the Scripps Institution of Oceanography; University of California, San Diego; Florida State University; and the National Center for Atmospheric Research, the extra waste heat generated from major Northern Hemisphere urban areas alters the temperature thousands of miles away, causing temperatures to increase by 1 degree Celsius in some remote area. But in areas of Europe, the waste heat cools the area by 1 degree Celsius. Most of the temperature decreases during the fall.

"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 statement.

The net outcome on worldwide mean temperature is negligible. Worldwide there is an increase of 0.01 degrees Celsius, as the total heat waste emitted is just 0.3 percent of the heat that is being transported to higher latitudes by atmospheric and oceanic circulations.

According to scientists, the effect of waste heat from cities is different from that of urban heat island effect. This study shows the heat being produced is projected directly into the atmosphere.

The consumption of energy, from heating buildings to powering vehicles, was analyzed by Hu, along with lead author Guang Zhang of Scripps and Ming Cai of Florida State University. With the help of a computer model of the atmosphere, they noticed that the waste heat has the capacity to widen the jet streams.

The waste heat emitted from multiple urban areas together can warm the temperature thousands of miles away from the energy consumption area.

"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 said in a news release.

According to scientists, the normal atmospheric circulation systems above are being altered by the emission of the concentrated waste energy.  This alteration triggers the remote surface temperature to change that is miles away from the regions where waste heat is generated.

The study is published in Nature Climate Change.