We’re still not entirely sure how precipitation will change in the future; different models produce slightly different scenarios. It is important to incorporate this uncertainty into analyses of species richness and predictions of species distributions.
Data source: Current precipitation data from Robert J. Hijmans, Susan Cameron, and Juan Parra, WorldClim-Global Climate Data, University of Berkeley, USA, retrieved from WorldClim.org. NSF-DOE-NCAR layer from Community Earth System Model ver. 1.0 (CESM1-CAM5-1-FV2).