The Health Costs of Wisconsin’s 2012 Heat Wave

Climate change poses multiple threats to human health, including the spread of vector-borne and waterborne disease, reduced air quality, and more frequent extreme weather events. However, the economic costs associated with these types of anticipated adverse health effects are neither adequately understood nor sufficiently considered in climate change mitigation and adaptation policy discussions. These costs could be particularly important in the United States, which has some of the highest health care costs in the world. We deploy a cost-of-illness methodological approach to estimating health costs through case studies from the past decade that exemplify the types of events strengthened by climate change. This approach draws on data collected by the Agency for Healthcare Research and Quality, specifically the Healthcare Cost and Utilization Project (HCUP) and the Medical Expenditure Panel Survey (MEPS), along with wage data reported by the Bureau of Labor Statistics and estimates of the Value of a Statistical Life (VSL), to supplement public health surveillance data.

In the midwestern United States, recent research suggests that emergency department visits for hyperthermia could triple by 2050 due to climate change, which is expected to increase the strength, duration, and frequency of heat waves. As a case study of heat-related health impacts, in July 2012 Wisconsin residents experienced record high temperatures over a span of one week, which caused elevated levels of heat stress, heat stroke, and heat exhaustion across the Upper Midwest. Several century-old daily record maximum temperatures were tied or broken during this heat wave, as well as new record high minimum temperatures. Using heat stress health outcome data collected by Wisconsin’s Environmental Public Health Tracking program and a combination of state- and national-level hospital cost data from HCUP and MEPS, we estimate the total health costs associated with this heat wave at $244 million statewide. This total includes $230 million in VSL for 25 heat-related premature deaths statewide and $14 million in morbidity costs stemming from hundreds of excess hospitalizations and emergency department visits, including bills for medical care, outpatient expenses, costs for prescribed medications, and lost wages during hospital stays.

This study builds upon prior climate change valuation research by integrating recent data from state and national health surveillance systems to consider morbidity and mortality costs in a consistent way. In doing so, we demonstrate a conceptual framework for the estimation of other health costs related to climate change in the United States using publicly available data sets and provide a methodology for quantifying the health costs of heat waves in other areas.

Beyond Wisconsin, summer 2012 temperatures ranked in the warmest 10% for 27 other states, and daily record high temperatures have lately been observed twice as often as record low temperatures in the US. According to the Third National Climate Assessment, by 2100, historical once-in-20-year extreme heat days could occur every two or three years over most of the US. Therefore, the single heat wave we examined in one state could signal hundreds of billions of future personal and societal costs for future heat waves nationwide. This research further illuminates the need for urgent action to respond to climate change and highlights the need for robust public health preparedness and surveillance efforts on climate-sensitive health conditions. Our findings demonstrate that a cleaner, low-carbon energy system could help the US to achieve billions of dollars in health cost savings, avoid thousands of heat-related deaths and other human pain and suffering, and enhance productivity, community security, and overall well-being.