Wednesday, August 1, 2018
Research Summary: Valuing the Global Mortality Consequences of Climate Change Accounting for Adaptation Costs and Benefits
- The cost of climate-driven changes in global mortality risk alone are as large as previous estimates of the economy-wide toll of climate change, according to an analysis of mortality data from 56% of the world’s population. In the first global, empirical study of mortality risk to capture both the costs and benefits of climate adaptation, researchers at the Climate Impact Lab find the increased global mortality burden from climate change to be 3.7% of global GDP by the end of century if past emissions trends continue.
- Utilizing a unique, big data approach to generate global information, the Climate Impact Lab finds that a metric ton of CO2 emitted today generates a median mortality risk of roughly $39 in a high emissions scenario. This value represents a “partial” social cost of carbon (SCC) that accounts for the value of lost life, as well as the net costs of adaptation to withstand temperature extremes, but excludes all other climate impacts. As a basis of comparison, a leading model that had not relied on similar data-driven approaches estimated the total mortality impacts of climate change at less than $1.50 per metric ton (Diaz 2014).
- The analysis is conducted with the most comprehensive data set ever compiled on mortality, historical temperature, income, and climate simulations. For example, it is derived from data covering 399 million deaths all over the world over the last several decades—accounting for different incomes, climates, and varying levels of development — and modeling future population and income growth.
- This research demonstrates the importance of updating estimates of the SCC used in policymaking to incorporate empirically-derived damage estimates. For comparison, the Obama administration’s most recent estimate of the economy-wide cost of climate change was roughly $41 per ton. In 2017, the National Academies of Science recommended ways in which the U.S. government should update this estimate to incorporate the most recent scientific and economic research. The Climate Impact Lab’s work shows that updating the mortality cost estimates alone would significantly alter any economy-wide number.
- Even after accounting for adaptation, an additional 1.5 million people die per year from climate change by 2100 if past emissions trends continue. For comparison, road injuries killed roughly 1.4 million people worldwide in 2016, and diabetes, ranked as the seventh leading cause of death worldwide, killed 1.6 million people in 2016. These projections include net gains in many regions of the world where lives will be saved from fewer cold days.
- Extreme heat is measurably deadlier for the poorest third of the world, and the decline in cold-related deaths does not offset the harm caused by temperature rise. Higher incomes make societies more resilient to extreme heat, allowing people to make a range of protective investments, including in air conditioning and better building insulation. But for the most vulnerable developing countries, even optimistic economic growth projections do not provide complete protection. The findings show warming caused by an additional ton of CO2 harms 72 percent of the global population, while the rest benefit on net, primarily due to a decrease in cold days.
Climate Impact Lab