Accounting for adaptation when projecting climate change impacts on health: a review of methods

Abstract

Abstract Exposure to high and low temperatures can cause harm to health. Temperature related health effects are likely to increase in the future, due to global warming, unless populations can adapt to a warming environment. Adaptation occurs through multiple mechanisms, however, the amount that populations may adapt to rising temperatures is unclear. There are currently a variety of methods used to include adaptation in projections, but it is unclear how underlying assumptions are made and whether they are based on evidence. With increasing interest from decisionmakers around implementation of adaptation strategies, an important step in responding to climate change will be to understand how adaptation can statistically be incorporated when estimating future health burdens. A systematic scoping review was conducted to identify all quantitative methods to include adaptation in studies projecting future temperature-related health impacts under climate change. Approaches employed in studies were coded into methodological categories. Advantages and disadvantages of each method were also explored, along with the empirical basis for model assumptions. Eight methodological categories were identified from the included fifty-nine studies. More recent methods of including adaptation in projections use a combination of approaches or modelling adaptation based on specific adaptation strategies or socioeconomic conditions. The most used approaches in the literature to model adaptation are heat threshold shifts and reductions in the exposure-response slope. Just under 20% of studies were categorised as using an empirical basis for statistical assumptions. Including adaptation in projections considerably reduced the projected temperature-mortality burden in the future. Researchers should ensure that all future impact assessments include adaptation uncertainty in projections and assumptions are based on empirical evidence where possible. Key messages • Including adaptation in future projections considerably affects temperature-related mortality numbers. • All future impact assessments should include adaptation uncertainty and assumptions should be based on evidence where possible.