Heat released from modern day, energy-hungry metropolises is changing the weather thousands of miles away, scientists discovered in a new report, according to LiveScience.com.
The released heat is affecting temperatures in areas more than 1,000 miles away. Known as "waste heat," the released heat is warming parts of North America by roughly 1 degree Fahrenheit, and areas of northern Asia by as much as 1.8 degrees Fahrenheit, while its cooling parts of Europe by a similar amount, scientists reported in the journal Nature Climate Change.
The released heat is even apparently changing atmospheric circulation, including jet streams, which are strong narrow currents of wind blowing from west to east and north to south in the upper atmosphere.
Scientists believe the impact of "waste heat" on regional temperatures may help explain a question of global warming: Why do some areas have warmer winters than predicted by climate models? Researchers said the results suggest this phenomenon should be accounted for in future models forecasting global warming.
"There's a tendency in climate science to overlook the effects of cities," Brian Stone, a professor of city and regional planning at Georgia Tech, told LiveScience. "Cities occupy just a few percent of the global land surface, but the amount of energy released as waste heat is contributing downwind to pretty significant changes in climate. I hope this will encourage us to focus more on cities as important drivers of climate change," added Stone.
Scientists have known for years that cities are warmer than their surroundings due to what's called the "urban heat island effect" - buildings, pavement and other building materials retain heat, preventing it from reradiating into the sky.
For the new study, scientists looked at a different kind of "urban heat." This time researchers focused o the heat directly produced by transportation, heating and cooling units, and other energy-consuming activities.
"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," said study researcher Aixue Hu, of the National Center for Atmospheric Research (NCAR), in a statement. "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."
Hu and his team of researchers studied the energy with the widely used National Center for Atmospheric Research (NCAR) model, which takes into account the effects of greenhouse gases, topography, oceans, ice and global weather, according to LiveScience.
The team of scientists ran the model with and without the effect of human energy consumption to investigate if it could account for large-scale regional warming. When scientists included human-made energy in the model, the "heat waste" led to winter and fall temperature changes of up to 1.8 degrees F in mid- and high-latitude parts of North America and Eurasia.
"The energy consumption in highly populated areas can cause changes in wind patterns, and that causes climate change far away from the heating source," said meteorologist and study author Ming Cai of Florida State University.