## Structured Abstract

### INTRODUCTION

> Forests across the globe face increasing risks from natural disturbances such as wildfires, insect outbreaks, and windstorms. These disturbances are highly sensitive to changes in the climate system and have already increased in many parts of the globe recently. Changing disturbance regimes can substantially alter ecosystems, e.g., through changing their demography and habitat value as well as altering the ecosystem services they provide to society. Anticipating potential future disturbance change is thus crucial for forest policy and management. However, projecting future disturbance regimes remains challenging because there are intricate interactions between individual disturbance agents, and feedbacks between vegetation development and disturbance change could considerably dampen or amplify climate impacts.

### RATIONALE

> Here, we present a modeling framework to simulate future trajectories of forest disturbance at high spatial resolution (100 × 100 meters) and across a large spatial extent (187 million hectares of forests in Europe). We leveraged a deep learning–based simulation framework to integrate a large body of local projections made by process-based forest models with climate-sensitive disturbance modules for wildfire, windthrow, and bark beetle outbreaks. Our modeling framework is designed to capture crucial disturbance processes such as the spatial spread of fire and bark beetles across forest landscapes and incorporates disturbance interactions and vegetation feedbacks. Our specific objectives were to quantify potential changes in stand-replacing forest disturbances in Europe until the end of the 21st century under different scenarios of climate change and to assess impacts of disturbance change on Europe’s forest demography.

### RESULTS

> Forest disturbances in Europe are highly likely to increase in the coming decades. Simulated future levels of disturbance were higher than those observed for the period 1986 to 2020 under all climate scenarios. Under scenarios of unabated climate change, the simulated area disturbed more than doubled by the end of the century (+122%). In scenarios assuming effective emissions reduction, peak disturbance was reached by midcentury. Wildfire was the disturbance agent most sensitive to changes in the climate system, heavily affecting Mediterranean areas but also expanding into temperate and boreal regions. Vegetation feedbacks dampened climate-induced disturbance change but were not able to completely buffer from disturbance increases. We project profound implications of future disturbance change on Europe’s forest demography, with the share of young forests increasing by up to 14% and old forests decreasing by up to 3% relative to simulations without changing climate and disturbance regimes.

### CONCLUSION

> The large-scale changes in forest disturbance regimes projected for the coming decades have important implications for biodiversity and the ecosystem services provided by forests. They could, for instance, hamper policy goals of using nature-based solutions for climate change mitigation, further amplifying climate change. Consequently, forest policy and management need to plan for a future with more disturbance. Nonetheless, our results highlight that mitigating anthropogenic climate change remains a potent lever for limiting future disturbance risk and safeguarding forests and their services to society.

Climate change will increase forest disturbances in Europe throughout the 21st century