Climate Change Mitigation: Assessing Strategies that Offer Potential Human Health Benefits

Climate change mitigation strategies, including efforts to reduce greenhouse gas emissions, are not specifically designed to improve human health but could potentially do so anyway. A review in this issue of EHP critically examines different models for estimating these so-called co-benefits and highlights improvements that could help assess which mitigation strategies are the most promising for both climate and human health. 1 Mitigation strategies to reduce greenhouse gas emissions include shifting from fossil fuels to renewable energy sources, reducing energy use and waste, and improving transportation options. 3 These strategies may also reduce air pollution, improve water quality, and promote physical activity. Characterizing the potential scope and scale of these health co-benefits can help policy makers prioritize mitigation actions against a backdrop of finite time and resources. In constructing models to estimate co-benefits, experts must consider which health factors to include and how sensitive they are to mitigation actions. They must also consider key methodological issues such as sources of uncertainty and the possibility that some mitigation actions may be accompanied by low-probability events with highly adverse health impacts (e.g., a nuclear power plant disaster). These hypotheticals are challenging to characterize and quantify. Modelers also must interpret the results, for example, by using discount rates—complex calculations that convert anticipated future intervention costs, impacts on the climate, adverse health effects, and health cost savings, to their present-day value. " Discount rates are central to all decisions with long-term implications, and the co-benefits of mitigation activities have multiple costs and benefits distributed over time, " says lead author Justin Remais, an associate professor in environmental health at Emory University. " We need to consistently account for the relative value of near-term versus long-term benefits and costs. " But choosing an appropriate discount rate is challenging because it is based on a number of unknowns, including future generations' wealth. The rate must also accommodate the social values of the current generation—for instance, how much people are willing to sacrifice their own comfort for an uncertain benefit to their descendents. Discount rates currently are not applied consistently across co-benefit models, something the authors recommend changing. They also suggest that policy makers be involved from the outset in developing models. Finally, they recommend that co-benefits modelers evaluate mitigation strategies on the basis of many criteria simultaneously , including not just health and climate impacts but also economic growth and political acceptability. " [This review] is …