Battling the Urban Heat Island Effect

As urban building sprawl increases, the sheer volume of concrete and asphalt surfaces is creating a situation known as the Urban Heat Island (UHI) effect—a development that is said to be causing temperatures to rise in cities all over the world. And while researchers and scientists continue to explore how to control or reduce the heat buildup, most American city dwellers don’t appear to give the concept of UHI much thought. And, says one report, they should be.

The report cites the city of Phoenix, Arizona as “a prime example of warming up with growth.” A graph illustrates the point as well as any thousand words: Referencing temperature measurements at two different locations – the city’s urban airport and the Casa Grande National Monument, an historic site of Desert People ruins located outside of the city – the graph shows that, as of 1950, an average daily low temperature of 55 degrees Fahrenheit (airport) and 50 degrees (monument).

By the mid-1970s, however, those lows have increased to about 62 (airport) and 52 (monument). Fast forward to 2006, and the figures now read 64 (airport) and 53 (monument). This suggests that, over the last 50 or so years, urban sprawl around the city’s airport has contributed to rising temperatures in that area, while temperatures at the monument have remained more stable. Since the population is likely to continue to grow, methods must be undertaken now to slow the UHI effect.

Those include: Greenbelts, urban tree canopies and sustainable parks, some of which take the form of golf courses and walking trails; porous asphalt surfaces for roads, parking lots and streets built over filtered underground spaces that can store storm water; and, reflective (usually white) roof surfaces that, in some cases, can wind up being as much as three times more effective than “green” roofs in combating climate change.

On an individual level, the UHI report suggests that people consider electing politicians who will advocate for sustainable urban living; spreading the word about the issue by talking with neighbors and sharing information; and, adapting personal living areas by planting more trees, upgrading insulation, installing sun-blocking shades on windows and going with a lighter color roof surface when it’s time for a replacement.