The heat produced by in cities like New York and San Francisco may be contributing to warming in areas up to 1,000 miles away, according to National Geographic News.
Scientists have long been familiar with the “urban island heat effect,” which generally leads to higher temperatures in cities than in suburban and rural areas.
However, according to a new study from the Scripps Institution of Oceanography at the University of California, San Diego, the heat generated by cities in the Northern Hemisphere is altering the jet stream – a current of air high above the surface of the Earth – and other major atmospheric systems, resulting in an increase in winter temperatures of up to 1.8°F (1°C) in faraway rural areas.
According to the new models, air rising off of urban areas can interfere with the jet stream, allowing warmer air from the Equator to flow farther north, according to National Geographic News.
“The changed circulation is thought to have an opposite effect in Europe, causing a cooling effect that amounts to 1.8°F (1°C), experienced mostly in the fall,” NBC News reported.
The authors of the study, published in the journal Nature Climate Change, said that urban heat might be behind some parts of the planet warming faster than models have predicted, NBC News reported.
The researchers found that areas most significantly impacted by this urban heat effect were Siberia and northern Canada, which can see temperatures rise 1.4°F to 1.8°F (0.8°C to 1°C) due to urban heat from cities thousands of miles away affecting the jet stream.
The 86 major metropolitan areas of the Northern Hemisphere cover only 1.27 percent of the Earth’s surface. But those areas consume 6.7 terawatts (one terawatt equals 1 trillion watts) of energy annually – representing 41.8 percent of annual global energy consumption, National Geographic News reported.