Mapping climate-resilient tea zones in India under climate change: regional suitability projections for the northeast and Western Ghats using ensemble modelling

Tea cultivation is highly climate sensitive. Yet fine-scale projections of future climatic suitability across major tea landscapes of India remain limited. Here, we developed parallel regional ensemble species distribution models for Camellia sinensis across northeast India (including North Bengal hill districts) and southwest India (part of the Western Ghats) to evaluate baseline (1970–2000) and future climatic suitability under three Shared Socioeconomic Pathway scenarios using two General Circulation Models. Presence locations were compiled from field observations, digitized tea-estate points, biodiversity databases, and literature, and were spatially rarefied to reduce sampling bias. Nineteen bioclimatic variables were screened for multicollinearity, retaining five predictors per region. Ensemble projections were developed in R using eight algorithms with repeated resampling and evaluated using AUC and TSS. Future suitability was projected using two CMIP6 GCMs (HadGEM3–GC31-LL and IPSL-CM6A-LR) under SSP1-2.6, SSP2-4.5, and SSP5-8.5 for mid-century (2041–2060) and end-century (2070–2100). Models showed strong discrimination (AUC 0.98–0.99; TSS 0.85–0.97), and mean temperature of the wettest quarter emerged as the dominant predictor in both regions. Baseline conditions indicated a higher proportion of very high suitability in the northeast (31.09%) than in the southwest (5.58%), where very low suitability predominated (80.55%). Future projections indicated a redistribution of suitability, with displacement and fragmentation of high-suitability zones alongside declines in very high suitability and a net contraction of suitable areas. The resulting suitability-change surfaces provide a useful first-pass screening layer for climate-risk zoning and for identifying relatively resilient, climate-stressed, and transition zones to support climate-resilient tea planning in India.