The Impact of CO₂-Driven Vegetation Changes on the Future of Flash Drought

Le résumé fourni par la source

Vegetation plays a crucial role in soil moisture regulation and the development of rapid-onset droughts known as flash droughts. We use climate model experiments with the Community Earth System Model (CESM2) to examine how vegetation responses to rising CO2 impact projections of future flash drought in the Northern Hemisphere mid-latitudes. By isolating the influences of CO2 fertilization and CO2 stomatal conductance effects from CO2 radiative forcing, we find that 1) CO2-induced changes to plant characteristics are of sufficient magnitude to modify flash drought characteristics, 2) CO2 fertilization effects counteract the CO2 stomatal conductance effects on projected flash drought occurrence, and 3) the combined influence of vegetation’s response to rising CO2 can either amplify or counteract CO2 radiative-driven flash drought changes depending on location. In water-limited regions such as the western U.S., the Mediterranean Basin, the Middle East, and west/central Asia where CO2 fertilization dominates and surface vegetation strongly controls water availability, elevated leaf area offsets reductions in stomatal conductance and transpiration, increasing the likelihood of future flash droughts. Vegetation-driven increases in flash drought in these areas are generally aligned in sign with projected increases due to radiative forcing. Conversely, in more energy-limited regions like western Canada, East Asia, and parts of Europe, preserved soil moisture from reduced stomatal conductance and transpiration suppresses flash droughts despite increase in leaf area from CO2 fertilization. These reductions in flash drought from vegetation counteract radiative-driven increases. This study elucidates the physical processes behind projected flash drought development, improving predictive capabilities and mitigation strategies.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.