Disproportionate lifetime exposure of young people to extreme fire weather in Portugal and Europe

Climate change is driving increased fire weather across the world: hot, dry and windy conditions lead to higher danger of fire ignition and spread and make fire suppression more difficult. With further warming, fire weather is projected to increase across the world. This means today’s children and young people will be exposed to ever more fire weather during their lifetimes. In this study, we analyze projections of extreme fire weather over Portugal and Europe from an ensemble of CMIP6 global climate model simulations previously bias-adjusted and downscaled to a 0.1º spatial resolution using ERA5-Land. We define extreme fire weather as days that exceed the 95th percentile of local fire weather index (FWI) values calculated from a 1985-2014 reference period. We then apply a lifetime exposure methodology at national and sub-national (NUTS3) spatial scales, using spatially explicit data on population density and life expectancy to estimate the exposure of different generations to extreme fire weather under different warming pathways. We use a GMT-based remapping technique and a multi-model ensemble approach to emulate fire weather projections under policy-relevant warming pathways ranging from 1.5ºC to 3.5ºC of warming in 2100. 

We find that young people will be disproportionately exposed to extreme fire weather compared to older generations across all warming pathways, while also standing to benefit most from ambitious mitigation. In Portugal, lifetime exposure to extreme fire weather among the youngest cohorts is twice that of their counterparts born in 1950 under current policy projections but is substantially reduced under a 1.5 °C pathway. Similar intergenerational gradients emerge across Europe, with spatial heterogeneity at the national and sub-national level, and the greatest increases in exposure in Mediterranean and Southern Europe and parts of Eastern Europe. When using absolute fire danger thresholds (38 ≤FWI<50 and FWI≥50) instead of relative indicators, similar intergenerational patterns are observed, but with markedly higher exposure in southern European regions characterized by hotter and drier baseline climates. Together, these results demonstrate a pronounced intergenerational inequity in exposure to extreme fire weather, even under low-warming, ambitious mitigation scenarios. At the same time, our results underscore the urgency of ambitious mitigation to limit cumulative exposure for younger generations.

This study also presents a new Python module that can be used to estimate lifetime exposure to any climate hazard, dem4cli. We provide a community tool to flexibly develop lifetime exposure research, laying the basis for further work to evaluate the intergenerational implications of a range of warming pathways and climate-related hazards.