Climate-driven expansion and richness hotspots of forest insect pests revealed by stacked species distribution models

Climate change has significantly altered global temperature and precipitation patterns, reshaped the distribution of forest insect pests and posed challenges to forest ecosystems. While previous studies have focused on single-species responses, regions exposed to multiple pest threats and their potential shifts under climate change remain poorly understood. Here, we used the ensemble modeling framework to predict the occurrence probabilities of 22 major forest insect pests in the Northern Hemisphere under historical and future Coupled Model Intercomparison Project Phase 6 (CMIP6) climate scenarios. Stacking all species’ binary predictions revealed current hotspots with the highest pest richness in East Asia, coastal Southern Europe and eastern North America. Future warming will shift these hotspots northward and reduce their spatial clustering. The total area under pest threats will expand by 2.66%–5.17% during 2041–2070 and by 1.00%–7.36% during 2071–2100, while that of individual species will contract by an average of 9.13%–11.69% and 14.32%–38.72% across these respective periods, varying by emission pathways. Complementarily, to capture the detailed magnitude of climate impacts beyond spatial range changes, our analysis of continuous predictions showed that average pest occurrence probabilities are expected to increase by 18.66%–30.02% and 19.67%–48.77% during 2041–2070 and 2071–2100 respectively. These probability changes exhibit a distinct latitudinal pattern: probabilities rise north of 41°N while declining southward. Model projections varied significantly across emission pathways and General Circulation Models (GCMs). This study presents a comparative framework to assess the outbreak risk of multiple pests under a changing climate, providing spatially explicit guidance for cross-border pest control and climate-adaptive forest conservation strategies.