How much heat do all the air conditioners pump into Chicago’s “heat island” and how does that affect our air temperature?
I can’t quantify it specifically, but make no mistake that air conditioners do contribute to the urban heat island effect. Years ago, University of Chicago tornado researcher Dr. Ted Fujita cited the vented heat from air conditioning as one of the factors that he believed produced the heating over cities which might weaken some tornadoes in the city by one Fujita-scale level. However, it is believed this applies mainly to weak tornadoes; stronger tornadoes would likely be unaffected.
Chicago’s heat island, strongest at night, results from several factors, including more concrete and asphalt, greater concentration of buildings, less cooling vegetation (especially trees) and more vehicles and industry.