Nested within the global warming problem that has resulted from greenhouse gas emissions and atmospheric accumulation, the urban heat island (UHI) is a specifically local warming problem that is becoming critical in most metropolitan areas of the world, due to urbanization, construction, and the conversion of green spaces into impervious surfaces. The UHI aggravates heat stress health effects, increases ozone surface concentrations, and leads to higher electricity consumption, with resulting pollution emissions from the burning of fossil fuels. I will first provide illustrations of the UHI and its local factors, and discuss the possible strategies to mitigate it. Next, using Columbus as a case study, I will report results from recent research with graduate students, including the construction of a virtual three-dimensional (3D) city, the use of satellite remote-sensing imagery, the generation of land-use maps, and the application of statistical methods to capture the relationship between observed land surface temperatures and measures of greenery, water, impervious surfaces, solar radiation, and 3D measures of the canyon structure of the urban core. I will illustrate how expanding greenery at both ground level and on building roofs can reduce temperatures. I will also show how the UHI varies across seasons, and the dual beneficial role of vegetation, reducing temperatures in the summer, but increasing them in winter.