Maps Show Low-Income Neighborhoods Especially Vulnerable to Heat Waves
When people refer to "heat maps," they can be referring to spectrum-colored maps of values (e.g., maps that show red, yellow, green, etc., based on a range of values), or actual maps of the weather (such as on the back page of USA Today :). In this post, we'll be examining both: heat maps of heat, so to speak.
Researchers at Arizona State University (Ruddell, Grossman-Clarke) recently announced findings showing that low-income neighborhoods tend to be hotter than their wealthier counterparts during the summer. This can be attributed to several factors, especially in the desert of Phoenix, but one of the main environmental factors is that low-income neighborhoods tend to have more pavement and less substantial vegetation. Both of these issues contribute to the so-called "heat island" effect where cities become giant heat sinks and radiators during the summer.
While not situated in the desert, Chicago can experience incredible heat waves, which are then amplified by the heat island effect. The City has tried to mitigate the heat island effect with various initiatives, including the "green roofs" rooftop garden program. Chicago's Department of the Environment released an (undated, unattributed) map displaying heat islands throughout the city. While the most obvious danger spot is in the Northwest Industrial Corridor (very little vegetation, large expanses of asphalt, concrete, and tar-roof buildings), there are numerous heat islands located throughout the south and west sides, especially when compared to neighborhoods like Lincoln Park or North Center.
Although 2009 was one of the coolest summers on record in Chicago, many of us remember the Great Heat Wave of 1995, which killed over 700 people (twice as many as the Great Fire of 1871). Author Eric Klinenberg performed a "social autopsy" of the event in his book "Heat Wave," trying to determine why the elderly and people in low-income neighborhoods were most vulnerable. In addition to the environmental factors mentioned above, residents of low-income neighborhoods are less likely than their high-income counterparts to have air conditioning sufficient to counteract a major heat wave. In addition, some people had air conditioning but wouldn't use it because of the additional cost (many people in the city, however, lost power for days, so this wouldn't have even been an option for many residents). Finally, the elderly residents in low-income areas who made up the majority of victims were less likely to leave their windows open due to concern about crime.
This map from Klinenberg's book (highly recommended) powerfully illustrates the correlation between low-income communities and deaths from the Great Heat Wave:
One interesting thing about the Arizona research is that (as far as I understand it) they didn't measure specific temperature differences over an entire summer in various neighborhoods. Instead, they used weather service models applied to the specific topography/environment of the Phoenix metro area to derive their data, then verified it against a small set of actual records. I'd be interested to see what variations the Chicago area experiences during a heat wave - what is the difference caused strictly by geography and the structural/environmental factors?
These maps and facts make me wonder what role that GIS and mapping tools will play in a future heat wave response: combining heat island pattern data, meteorological data, and data from the social service agencies (such as the Department of Aging and related organizations) could lead to maps of "target areas" where the elderly poor are most likely to suffer. A public participation GIS web app could match elderly "at-risk" populations with nearby volunteer or NPO-based "heat monitors" to check on them during the heat wave. Maps depicting which areas were worst affected would allow the city to target those areas with temporary cooling stations (such as empty school classrooms and pre-positioning spare city buses to use as mobile cooling centers).