Temperature-Related Mortality Impacts under Climate Change Scenarios Consistent with the Paris Agreement: A Multi-Country Analysis

Abstract

Background/Aim: The recent international agreement reached in Paris aims at keeping the increase in global mean temperature (GMT) below 2°C, and it pursues efforts to limit it below 1.5°C. Here we provide evidence on temperature-related direct mortality impacts under these and more extreme climate change scenarios, using a worldwide multi-country dataset. Methods: Two-stage time series analysis using distributed lag non-linear models and multivariate meta-analysis to estimate temperature-mortality relationships for 412 locations within 20 countries in 1985-2012. Future impacts, quantified as attributable risks for non-optimal temperature and for cold and heat separately, were computed under scenarios consistent with 1.5°C, 2°C, 3°C, and 4°C increase in GMT, defined by corresponding 20-year windows identified in temperature series projected along the 21st century using four global climate models. Results: Across different regions of the world, a rise from 1.5°C to 2°C in GMT would generate 0.20%-1.40% increases in heat-related and 0.30%-0.67% decreases in cold-related mortality. Mild temperate areas such as North Europe and Australia would experience a small but significant net decrease (0.28% and 0.47%, respectively), while hotter places such as South Europe and South-East Asia would face a larger significant net increase (0.61% and 0.73%). Changes are close to null in areas characterized by diverse climatic conditions, such as North and South America and East Asia. More extreme scenarios with GMT rising to 3°C-4°C would present more dramatic heat-related impacts, especially in hotter places, with net increases up to 7.10% in some tropical areas. Conclusions: This large worldwide assessment provides evidence of potential health benefits of enforcing mitigation strategies to reduce global warming. Compliance with the limits set by the Paris Agreement (2°C) would prevent dramatic increases in mortality projected in many regions, while more ambitious targets (1.5°C) would be beneficial for hotter tropical areas where a large proportion of world population lives.