Islands in the Sun:
Redesigning Cities to Mitigate the Urban Heat Island Effect
Islands in the Sun is a four-year research project funded by the University of Minnesota’s Institute on the Environment and the College of Food, Agricultural, and Natural Resource Sciences to monitor the urban heat island of the Twin Cities Metropolitan Area (TCMA). Profs. Peter Snyder and Tracy Twine, atmospheric scientists in the Department of Soil, Water, and Climate on the Saint Paul campus, are coordinating the project. The goal of this project is to better understand the mechanisms contributing to urban heat islands with a goal of finding ways to lessen their effects through landscape design. Given that more than half the global population lives in cities, there is urgent need to understand and mitigate urban heat island effects, especially during heat wave events when the risk of heat-related illness and mortality can increase dramatically.
Urban heat islands are regions of strong warming that are localized around the core downtown region of a city with progressively lower temperatures as one travels away from the central region of warming – hence the name “heat island”.
Urban heat islands exist because of large differences in land use, building materials, and vegetation between cities and their rural surroundings. This difference can be in excess of 1-10°F during the daytime and as much as 12-20°F at night. In addition, the localized warming has the potential to alter patterns of precipitation in metropolitan regions and the surrounding countryside and perhaps even influence the frequency and severity of severe weather.
The economic, environmental, and human toll of urban heat islands is far-reaching and significant:
- The additional energy necessary to cool buildings burdened by urban heat islands amounts to billions of dollars annually in the U.S. alone.
- Ground-level ozone, exacerbated by the additional warming of urban heat islands, directly harms the cardiovascular health of urban and suburban residents and the productivity of croplands downwind of urban areas.
- Rainwater, warmed by buildings and roads in urban areas, flows into lakes and streams where it alters the aquatic biology.
The data that is collected in and around the TCMA will be used to comprehensively map and understand the annual, seasonal, and daily behavior of our urban heat island. The data will also be used in conjunction with numerical models to explore how changes to the urban landscape could contribute to mitigating the deleterious effects of urban warming. Additionally, we will be evaluating the effectiveness of different engineering and building design practices that can reduce energy consumption and reduce urban warming.