Mapping Climate Change Vulnerability

mapPhD candidate Colleen Reid and researchers at the University of Michigan and Harvard University had previously developed a Heat Vulnerability Index (HVI) to identify communities in the United States that are most susceptible to global warming. Recently, Reid teamed up with scientists at UC Berkeley and public health professionals who are part of the CDC’s Environmental Public Health Tracking Network to evaluate the HVI.

The study team focused on five states with health and population data from the Network. In all five states they found higher hospitalization and mortality rates on extremely hot days.1 Areas with higher vulnerability, as identified by the HVI, also showed higher rates of acute renal failure, electrolyte imbalance and nephritis in California, heat-related illness in Washington, all-cause mortality in New Mexico and respiratory hospitalizations in Massachusetts on extremely hot days.

Cities in North America will experience more extreme heat due to climate change, according to the fourth Intergovernmental Panel on Climate Change report. Its authors predict heat waves will increase in frequency and severity, leading to more illness and death, particularly among the young and elderly. In addition, respiratory disorders may worsen with changes in air quality.2

“The Heat Vulnerable Index shows a spatial pattern of health disparities,” says Reid, a doctoral candidate in Environmental Health Sciences at UC Berkeley. “Using the index, you could zoom in on areas in the United States that have higher expected vulnerability for adverse health effects from heat,” she notes. “There have been a couple of studies attempting to map heat vulnerability at the local level, but none of national scale.”

In a previous study published in Environmental Health Perspectives, Reid conducted a comprehensive literature review to identify 10 demographic and social variables that largely explain climate change vulnerability in the United States. She combined these ten factors into four statistically independent factors that represented different facets of heat vulnerability: socioeconomic and environmental vulnerability, social isolation, air conditioning prevalence and the portion of the population that is elderly or has diabetes.3 Next, she calculated the four values and combined them for each U.S. census tract, then mapped her results to show how heat vulnerability varies nationally.

“When our paper came out, lots of people contacted us wanting to use the index, but we were hesitant until we could validate our study,” said Reid. “We decided to validate the HVI with data from the Tracking Network and teamed up with states that had the information we needed.”

Reid’s COEH co-investigators include Director John Balmes, who was also the Principal Investigator of the Environmental Public Health Tracking (EPHT) grant from the CDC that funded the study. “When I first read Colleen’s HVI paper, I thought that validation of the tool for planning public health responses to heat waves could be done through the EPHT network,” said Balmes.

Research scientist Jennifer Mann and MPH student Kathleen Navarro participated from the UC Berkeley School of Public Health. Other co-investigators include Helene Margolis from the School of Medicine at UC Davis and Paul English from the California Environmental Health Tracking Program at the California Department of Public Health.

The studies were funded by the Centers for Disease Control and Prevention through the Berkeley Center for Environmental Public Health Tracking and the U.S. Environmental Protection Agency.

1Reid CE, Mann J, Alfasso R, English PB, King GC, Lincoln RA, Margolis HG, Rubado DJ, Sabato JE, West NL, Woods B, Navarro KM, Balmes JR. Evaluation of a heat vulnerability Index on abnormally hot days: an Environmental Public Health Tracking study.


3Reid CE,O’Neill MS, Gronlund CJ, Brines SJ, Brown DG, Diez-Roux AV, Schwartz J. Mapping Community Determinants of Heat Vulnerability. Environ Health Perspect. 2009 Nov.;117(11):1730-36.

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