Responses of extreme fire weather to CO₂ emission reductions and underlying mechanisms

While previous studies have reported an increase in future fire weather under global warming scenarios, there is still a limited understanding on how it may evolve under mitigation scenarios. Using idealized emission-driven climate simulations, this analysis examines changes in the extreme fire weather conditions under net-zero emission (ZeroE) and net-negative emission (NegE) scenarios. Compared to peak CO₂ levels, the NegE scenario achieves substantially greater fire danger mitigation, particularly in climatologically high-fire-danger regions, because of lower temperatures and increased relative humidity. In contrast, the ZeroE scenario leaves fire danger elevated globally, especially in Northern low-latitude regions. Regional responses are shaped by differences in atmospheric moisture supply, influenced by changes in the strength of the Atlantic meridional overturning circulation and the latitudinal position of the intertropical convergence zone. These findings highlight the crucial role of aggressive CO₂ removal strategies in mitigating fire weather dangers and underscore the limitations of ZeroEs alone in addressing global wildfire challenges.