Quantifying CO<sub>2</sub> forcing effects on lightning, wildfires, and climate interactions.

Verjans, Vincent; Franzke, Christian L E; Lee, Sun-Seon; Kim, In-Won; Tilmes, Simone; Lawrence, David M; Vitt, Francis; Li, Fang · Sci Adv · 2025

basic_science · Level V

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Abstract

Climate change affects lightning frequency and wildfire intensity globally. To date, model limitations have prevented quantifying climate-lightning-wildfire interactions comprehensively. We exploit advances in Earth System modeling to examine these three-way interactions and their sensitivities to idealized CO<sub>2</sub> forcing in 140-year simulations. Lightning sensitivity to global temperature change (+1.6 ± 0.1% per kelvin) is mitigated by compensating atmospheric effects. Global burned area sensitivity to temperature (+13.8 ± 0.3% per kelvin) is largely driven by intensified fire weather and increased biomass but marginally by lightning changes. We find a universal law characterizing regional-scale modeled fire activity and its CO<sub>2</sub> sensitivity, consistent with basic principles of statistical mechanics. Last, a negative climate feedback through intensified aerosol direct effect from fire emissions reaches an equivalent decrease of 0.91 ± 0.01% in CO<sub>2</sub> radiative forcing. However, this feedback contributes to polar amplification. Our analysis shows that climate-lightning-wildfire interactions involve multiple compensating and amplifying feedbacks, which are sensitive to anthropogenic CO<sub>2</sub> forcing.