Heat-related mortality impacts attributed to climate change: a global study over historical period.

OPS 13: Heat, cold and mortality, Room 117, Floor 1, August 26, 2019, 1:30 PM - 3:00 PM

Background & Aim: While it is widely accepted that climate change will increase heat-related deaths in the future, limited quantitative evidence exists on current and past impacts already attributable to climate change. This large global study aims at estimating the proportion of excess heat-related mortality attributed to global warming experienced in recent decades across various regions of the world, by comparing impact estimates derived under actual trends and pre-industrial projection scenarios.

Methods: We studied 601 locations across 30 countries included in MCC database for which observed daily temperature-mortality data was available for at least 2 years between 1995 and 2005. Location-specific summer-only temperature-mortality associations were estimated through two-stage time-series analyses with quasi-Poisson regression with distributed lag non-linear models and multivariate meta-regression. Excess mortality attributable to climate change was calculated as the difference in heat-related excess deaths occurring above the city-specific minimum mortality temperature, estimated using modelled temperature series consistent with current actual emission trends (“warming”) and pre-industrial forcings (“non-warming”), respectively, obtained from the ISIMIP2b database.

Results: Overall excess heat-mortality fractions of 1.60% [95%CI: 0.30–2.76] and 1.03% [0.13–2.04] were estimated during summer under the “warming” and “non-warming” scenarios, respectively. This translates to 35% of historical heat-excess mortality attributed to climate change. Statistically significant differences between scenarios were observed in Central America (0.80 [0.16–1.63] vs.0.29 [-0.02–0.86]), North of Europe (0.86 [0.09–1.53] vs. 0.61 [0.03–1.18]), Central Europe (2.62 [1.52–3.67] vs.1.62 [0.49–2.64]), South of Europe (8.00 [5.15–10.88] vs. 5.32 [1.95–8.50]), and Australia (1.54 [0.15–2.82] vs. 0.98 [-0.02–2.12]), translating to 63%, 29%, 38%, 34% and 36% of the heat-excess mortality attributed to climate change, respectively.

Conclusions: Our preliminary findings suggest that climate change is already responsible for a considerable increase in heat-related mortality burden. These results stress the importance of strengthening current mitigation strategies to reduce further warming of the planet and related health impacts.