Although meteorologists have long known that cities are warmer than rural areas because of all the people, buildings, cars and asphalt, etc., they are first realizing that the urban heat island (as it is called) created in metropolitan areas like New York, Tokyo and London may actually be working to warm up winters as far away as Alaska, Canada and Siberia.
“Unlike man-made greenhouse gases which cause global warming, however, the energy changes from urban heat is redistributing some of the warmth around the world,” explained study co-authors Guang Zhang of the Scripps Institute of Oceanography in La Jolla, CA, and Aixue Hu at the National Center for Atmospheric Research in Boulder, Co.
The pair came to their conclusion after examining computer models which showed that the heat from the cities appeared to be rising approximately a half mile up into the atmosphere, where it affected high altitude currents that dictate prevailing weather patterns.
In fact, the models have shown that parts of western Canada, as well as Siberia may actually be seeing a rise of 1.4-1.8 degrees Fahrenheit, compared to a half degree warmer temps in Minnesota and North Dakota. Oddly, the same effect seems to be cooling down autumns in the western United States, as well as Eastern Europe and the Meditteranean, as well as winters in other parts of Europe and the Pacific Northwest during the winter as “the jet stream is altered and weakened, keeping the cold air closer to the Arctic Circle and from dipping down,” explained Hu.
He also added that the “changes seem to vary with the seasons and by region because of the way air currents flow at different times of the year.