The urban heat island (UHI) phenomenon has been the subject of intense study over the past several decades. Initial focus on the causes of the UHI has led to a basic understanding of the factors affecting heat island development and magnitude. Related research into the effects of elevated urban temperatures on air quality, energy consumption, and human health has provided motivation for reducing the magnitude of the UHI. The information resulting from this body of research  has paved the way for development of strategies to mitigate urban heat islands. These strategies generally fall into two categories – increasing urban albedo (reflectivity to solar radiation) and increasing evapotranspiration. Albedo increases are generally accomplished through high albedo roofing and paving technologies. Increase in evapotranspiration is accomplished through a combination of decreasing the fraction of impervious surfaces and planting vegetation in urban areas (shade trees, vegetated walls, and rooftop gardens/ecoroofs).

This paper provides a brief overview of the recent history of UHI research and discusses in detail recent efforts at UHI mitigation. These efforts range from the development of mitigation technologies to computer modeling of their impacts and in situ evaluation of their performance. This paper builds on past efforts to summarize heat island mitigation progress (Estes, 2000), but attempts to be more comprehensive and more up to date. The presentation will conclude with a look at what the future might hold for heat island mitigation.