A watershed-scale assessment of climate change impacts on crop yields in Atlantic Canada

Abstract

Agriculture in Atlantic Canada (AC) is dominated by a rain-fed potato production system, with potatoes typically rotating with cereal crops such as barley and oats. Under rain-fed conditions, crop yields are sensitive to weather and its variations and are thus affected by climate change. Previous research regarding climate change impacts on crop yields in AC has been limited to a regional-scale assessment, mostly focusing on climate without considering real-world field conditions (e.g., soil and topography). In this study, an enhanced Soil and Water Assessment Tool (SWAT) model was used to estimate crop yields at the watershed scale under climate change conditions projected for the period of 2020–2099 using global climate models with three different greenhouse gas (GHG) emission scenarios from the Representative Concentration Pathways (i.e., RCP2.6, 4.5, and 8.5). Results suggest that climate change will negatively impact potato and barley yields under all three RCP scenarios. In particular, under the RCP8.5 scenario, there will be significant reductions (13–23%) in crop yields between 2060 and 2099. The leading cause of crop yield reductions is attributed to the soil water stress resulting from increased temperature and evapotranspiration during the growing season due to climate change. Elevated carbon dioxide (CO2) concentrations could potentially increase crop yields due to the CO2 fertilization effect. However, it is not enough to offset the negative impacts of soil water stress. Our results suggest that on top of controlling GHG emissions to below the RCP4.5 level, it is critical to develop and adapt crop, soil, and water management practices such as new crop-rotation systems, early planting dates, and supplemental irrigation to maintain future crop yields in AC.