The purpose of this study is to understand the dynamics of freshwater ecosystem services under future climate change scenarios. The InVEST Toolkit created by The Natural Capital Project was used to predict water yield and to assess potential areas of water risk in Canadian watersheds. To access the accuracy of the model, outputs from InVEST were validated against observed water yield for the baseline year of 2005. Additionally, using three climate change scenarios defined by the Intergovernmental Panel on Climate Change (IPCC) in its fifth Assessment Report, and results of the Canadian Global Coupled Model Version 4 (CGCM4) for key climatic variables, we have assessed the projected change in the chosen three ecosystems services for future timelines of 2025, 2050 and 2100. Future projections of water yield were compared to forty years of historic data for the given watershed to identify areas where future values varied significantly from the expected range.
When compared to observed data, the InVEST model systemically under predicts water yield in coastal watersheds and lowlands. However, with the exclusion of these areas, validation of InVEST with historic data shows an R²= 0.82 and RMSE= 97.45 mm. Across all time steps and climate models, spatial patterns show reoccurring trends of future drought prone areas in Central Canada and flooding in the Prairies and Arctic region. These future projections allow us to identify areas of significant projected declines of key freshwater ecosystem services, or conversely areas where provisioning of those services may increase. As such, our results can inform adaptation planning in watersheds across the country. Combined, these analyses create an important and novel way to communicate the current value of freshwater ecosystems in Canada, as well as the potential risk these ecosystems face in the future.