Projected changes in fire weather across South Asia using CMIP6 models under multiple emission scenarios

The frequency and severity of wildfires are increasing, with damaging effects on infrastructure, human populations and ecosystems. To inform risk mitigation planning, climate change projections are essential for assessing future trends in fire weather - meteorological conditions conducive to wildfire ignition and spread - and subsequently for identifying areas likely to face heightened wildfire risk in the future. This is particularly important in regions where wildfires are emerging as a notable threat in areas not historically considered fire-prone. One such example is South Asia, a region home to two billion people and already facing significant challenges associated with climate and environmental change. 

Here, we examine how fire weather is likely to respond to a changing climate in South Asia. We first evaluate the ability of 14 state-of-the-art Earth System Model (ESM) ensembles from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) to realistically represent observed mean, variance, and spatial variability statistics in the Fire Weather Index (FWI), using the ERA-driven global fire danger reanalysis as a reference. Those ESMs demonstrating an acceptable performance are used to quantify changes in the characteristics of a series of FWI-derived annual indicators throughout the 21st century under four emissions scenarios defined by the Shared Socioeconomic Pathways (SSPs). These projections are also analysed in relation to Land Use and Land Cover (LULC) classifications for each scenario. We find that seasonal means and annual maxima of FWI are projected to increase by up to 10% by the end of the century under the highest emissions scenario, while the incidence of extreme fire weather may rise by as much as 20 days per year under SSP5-8.5. Regarding projected changes across different LULC types, our results reveal significant positive trends in FWI metrics over forest and grassland areas under all SSP scenarios. 

Overall, our findings contribute to a better understanding of future fire weather in a region historically unprepared for wildfire threats. We conclude by discussing the implications of these results for a range of stakeholders and their potential to enhance planning and preparedness at national and regional scales across South Asia, supporting the development of long-term mitigation and adaptation strategies.