Urban Heat Islands Change the Weather

Asphalt shingled roofs, black paved roads, and fewer shade trees all create heat islands. Heat islands drive up temperatures sending the average temperature 5 degrees higher in urban areas than it is in the surrounding suburbs. That, in turn translates into an extra $4 billion in cooling costs in the United States each year. Heat islands also add to air pollution since higher temperatures enhance the chemical reactions that create smog. This is very apparent in places such as Orange County, California where the average temperature over the last 50 years has risen 7 degrees, Not only has the population soared from 216,000 in 1949 to 3-million in 2002, but all the orange groves were cut down to make room for condos, houses, shopping malls, parking lots, and golf courses. The loss of all those trees has had a devastating effect because trees are natural cooling systems. In other parts of the United States such as Texas and Illinois, these urban heat islands are contributing to increased storm systems and deadly heat waves. One of the ways to counteract this effect would be to change the color of roofing materials to utilize reflective paints, or light colored asphalts that would cool interior spaces, thus reducing the need for extensive air-conditioning.