Evaluation for Future Fire Impacts on Ecosystem Resilience and Carbon Budgets

As wildfires increasingly intertwine with our changing climate, there is a growing demand for our models to provide information on fire’s changing influence on the world's ecosystems and their ability to uptake and hold carbon. However, to do this, we need to find ways to assess our simulations and build confidence in their projections. In response, we introduce a targeted benchmarking framework designed to evaluate models' abilities in simulating long-term fire trends and their broader impacts on carbon dynamics and vegetation cover. The framework comprises five tests, scrutinising spatial and temporal variations in burnt areas, fire emissions, tree cover, and vegetation carbon while integrating substantial observational uncertainty.

Using the JULES-ES-INFERNO coupled fire-vegetation model driven by ISIMIP2a bias-corrected GCM output, we demonstrate the applicability of this framework, seeking feedback on its comprehensibility and relevance. Building upon this evaluation, we delve into the ramifications of climate policy and ecosystem resilience. Amid efforts to limit global warming to 1.5℃, our analysis reveals that fire, a pivotal but often overlooked component in climate models, already exerts significant pressure on global carbon storage. We identify a critical threshold of 1.07℃ (uncertainty range 0.8-1.34℃) above pre-industrial levels at which fire significantly impacts carbon dynamics, diminishing the effectiveness of land carbon sinks.

By integrating these insights into climate mitigation strategies, policymakers can better navigate the complex interplay between climate change, fire dynamics, and ecosystem resilience, thus fostering more robust approaches towards climate adaptation and carbon management. And by extensive and targeted model evaluation and benchmarking, we can build much needed confidence in these projections.