Quantitative risk assessment of the effects of climate change on selected causes of death, 2030s and 2050s

Future cause-specific mortality in 2030 and 2050 (in the absence of climate change) was estimated using regression methods for three development futures: base case, high growth and no growth scenarios. Global climate-health models were developed for a range of health outcomes known to be sensitive to climate change: heat-related mortality in elderly people, mortality associated with coastal flooding, mortality associated with diarrhoeal disease in children aged under 15 years, malaria population at risk and mortality, dengue population at risk and mortality, undernutrition (stunting) and associated mortality. Future climate change was characterized by a medium-high emissions scenario (A1b) run through three climate models. The counterfactual was a future world with population growth and economic development but with baseline (1961–1990) climate. The annual burden of mortality due to climate change was estimated for world regions. For most pathways considered, the results reflect both positive and negative impacts on health. Model uncertainty was assessed for each outcome, as far as technically possible.

Compared with a future without climate change, the following additional deaths are projected for the year 2030: 38 000 due to heat exposure in elderly people, 48 000 due to diarrhoea, 60 000 due to malaria, and 95 000 due to childhood undernutrition. The World Health Organization (WHO) projects a dramatic decline in child mortality, and this is reflected in declining climate change impacts from child malnutrition and diarrhoeal disease between 2030 and 2050. On the other hand, by the 2050s, deaths related to heat exposure (over 100 000 per year) are projected to increase. Impacts are greatest under a low economic growth scenario because of higher rates of mortality projected in low- and middle-income countries. By 2050, impacts of climate change on mortality are projected to be greatest in south Asia. These results indicate that climate change will have a significant impact on child health by the 2030s.

Under a base case socioeconomic scenario, it was estimated approximately 250 000 additional deaths due to climate change per year between 2030 and 2050. These numbers do not represent a prediction of the overall impacts of climate change on health, since it was not possible to quantify several important causal pathways.