Modelling biome shifts in the Indian subcontinent under scenarios of future climate change

The Indian subcontinent is expected to witness significant changes in climatic conditions in the future, but the implications of such changes for future spatial distribution of different biomes in the subcontinent are unclear. We sought to understand the potential shifts in the distribution of biomes in India by 2070 under different emission scenarios, identify biomes and regions of the country that are particularly at risk from future changes in climate, and quantify uncertainties associated with the predictions. We used an ensemble classifier (random forest) to model current and potential future distribution of biomes in India for different climate trajectories under the newly developed representative concentration pathway (RCP) scenarios. Climate projections from 19 and 17 different general circulation models (GCMs) were used to predict future biome distributions in India under the RCP 4.5 and RCP 8.5 scenarios respectively. For each scenario, model outputs from different GCM projections were combined using a simple majority voting criterion. Approximately 630,000 sq. km (18%) of the country is predicted to experience biome shifts under the RCP 8.5 scenario and 486,000 sq. km (14%) under the RCP 4.5 scenario by 2070. Drier tropical biomes are likely to be replaced by wetter biomes, while temperate biomes are predicted to be dominated by vegetation characteristic of a warmer climate in the future. There was a high to moderate level of agreement between predictions of different GCMs. Our results suggest that biome shifts will be largely concentrated in the east-central and northern parts of the country, with tropical and subtropical dry forests, savannas, grasslands and xeric habitats particularly at risk. Future studies should focus on elucidating the responses of different vegetation subformations within individual biomes in order to gain a finer-scale understanding of vegetation responses to future climate change in the Indian subcontinent.