Urban Heat Island Effect

An urban heat island is a metropolitan community with higher temperatures than nearby less developed or rural areas.  The increased temperatures above urban areas are a consequence of heat-retaining materials such as asphalt, concrete, rooftops, and other land surfaces manipulated by people.  For example, in a study by Buyantuyev and Wu (2010), nighttime ground surface temperatures in Phoenix, Arizona were predominately driven by the percentage of pavement cover in an area.  In the same study, the percentage of vegetation cover in an area was the main factor that affected daytime surface temperatures.  These results could prove to be costly for other southwestern cities.  One such city is Albuquerque, New Mexico where Nowak and Greenfield (2012) estimated that impervious cover increased by 1.8% and tree and shrub cover diminished by 2.7% between 2006 and 2009.

Changes in land cover can affect surface and air temperatures (image courtesy of http://explow.com/urban_heat_island)

Negative consequences of urban heat islands include increased cost and pressures on resources for cooling, air pollution, heat-related illness and death, and impaired water quality.  In many moderate to low-income communities, conventional methods for addressing urban heat island effect are costly, inefficient, and often do not address the problem (e.g. air conditioning units).