Abstract

We develop an integrated assessment model with endogenous population dynamics depending on the impact of global climate change on mortality. An age-dependent endogenous mortality rate, which depends linearly on global temperature increase, is introduced for five causes of death (heat-related, diarrhoeal disease, malaria, dengue and undernutrition). We calibrate this endogenous risk on data from World Health Organization (2014) and look at the impact of climate on population and the feedback effect on the economy in three scenarios: a business-as-usual (BAU) scenario, a 3◦C scenario and a 2◦C scenario. We obtain that climate-related deaths per annum ranges from 150,000 (in the near term) to more than 320,000 (at the end of the century) in the BAU, but are relatively constant (or slightly decreasing) around 150,000 in the 3◦C and 2◦C scenarios. Although these absolute values are large, they represent only a small fraction of total mortality so that total popula- tion is not much affected by the endogenous mortality risk in the next century. As a result, the feedback effect on the economy is negligible. Death is however concen- trated among the young and the old. We thus look at the number of years lost due to climate change in a given year and find figures ranging from 4 to 10 million. Interestingly, the number of years lost is constant (BAU) or decreasing (3◦C and 2◦C scenarios) through time due to changes in the age-composition of future populations. Population is ageing so that the additional mortality risk concerns more and more the elderly, hence reducing the number of years lost. Using standard levels of the value of a statistical life, we can estimate that climate change-related mortality is equivalent to a monetary loss around 0.2% to 0.5% of GDP

Co authors : Aurélie Méjean, Antonin Pottier et Marc Fleurbaey

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