CHAMPAIGN, Ill. — Rising temperatures and longer and more intense heat waves affect the safety of people around the world, particularly those in urban areas. In Chicago, it has become more challenging to help those most vulnerable to extreme heat events, as those residents have become more dispersed throughout the city and suburbs.
Bev Wilson and Arnab Chakraborty, University of Illinois urban and regional planning professors, looked at where those vulnerable populations live and how their locations have changed over time. They wrote about their research in the Journal of Environmental Planning and Management. Wilson and Chakraborty found that the locations of those most vulnerable to extreme heat – the elderly, people living alone, those with few social connections or no access to transportation – had steadily decentralized in the Chicago region from 1990 to 2010.
“A more dispersed and decentralized target population during an extreme heat event can make it more difficult to quickly and efficiently deliver relief and medical attention when needed,” they wrote.
Heat waves are an understudied consequence of global climate change, Wilson and Chakraborty said. They believe urban planners must pay more attention to mitigating the effects of extreme heat events and consider how best to help the most vulnerable residents.
“In this country, people don’t look at heat as a major killer, but the facts show that it is,” Chakraborty said.
The National Weather Service estimates that extreme heat is the largest cause of U.S. weather fatalities in the last 30 years, with an average of 131 deaths per year attributable to heat, Wilson and Chakraborty wrote. In July 1995, the Chicago area experienced one of the worst weather-related disasters in the history of Illinois, when more than 700 people died in Cook County during a five-day heat wave.
The Centers for Disease Control and Prevention found that the victims tended to share certain characteristics, including living alone, not leaving their homes daily, lacking access to transportation, being sick or bedridden, not having social contacts nearby and not having access to air conditioning, the authors wrote.
Wilson and Chakraborty looked at census data for the Chicago metropolitan region for 1990, 2000 and 2010 in order to identify the most vulnerable populations to extreme heat. They found strong concentrations of vulnerability in the south and west sides of Chicago and the inner-ring suburbs.
However, the location of those residents steadily decentralized by 2010. Some of the factors shaping those changes include redeveloping high-rise public housing projects using a mixed-income, scattered-site approach; gentrification of some neighborhoods; and the growth in the suburban share of the overall percentage of people living in poverty.
Wilson’s and Chakraborty’s approach emphasizes looking not just at where the greatest exposure to extreme heat is, but also the social factors that make people more vulnerable to extreme heat and affect whether they are able to adapt to the conditions.
Those with a fear of crime may be reluctant to open windows or go outside to alleviate the effects of the heat, for example. Residents may lack access to transportation to get to a cooling center. Income affects whether they have air conditioning or can pay the electric bills associated with running it. A language barrier, illness or a lack of social or family support may also affect whether someone will leave home to find a cooler place.
The latest research by Wilson and Chakraborty grew out of a website they created that integrates data on the environmental and social aspects of heat vulnerability. They said attention to the social aspects of vulnerability is lacking in most data and literature on extreme heat events.
The two researchers are part of a public/private coalition studying issues related to planning and responses to extreme heat that includes the Chicago mayor’s office, the Chicago Department of Public Health, the Office of Emergency Management and Communications, and the utility provider ComEd.
The coalition seeks to better integrate the data collected by the various agencies for a more comprehensive response. UI Labs, Microsoft and NASA are also involved in developing data and software tools that other municipalities might use to prepare for and manage heat emergencies.
Wilson and Chakraborty are interested in determining which data sets can help answer questions about heat vulnerability. They are looking at data that is broadly available and accessible to organizations. They also want to gain access to individual-level data that would include 911 calls for service and hospital admission information to better answer the question of which data best predict the location of vulnerable residents.
“We need to better understand where the most vulnerable people are in order to get to them quickly and to reduce their vulnerability over time through planning,” Chakraborty said.
“You can’t know that unless you collect and look at data. If you don’t know where vulnerable populations are, you can’t answer the question of where to have cooling centers. Data are needed in order to make more informed planning decisions,” Wilson said.
Such information can help cities with long-term planning issues, including modifying the albedo – the amount of solar radiation that is either reflected back or absorbed – with roofs painted white or planted with vegetation; increasing green infrastructure; and other measures to mitigate the effect of urban heat islands.
“As climate changes, cities not accustomed to looking at heat vulnerability are going to be forced to,” Wilson said.