Abstract
Using climate scenarios from only 1 or a small number of global climate models (GCMs) in climate change impact studies may lead to biased assessment due to large uncertainty in climate projections. Ensemble means in impact projections derived from a multi-GCM ensemble are often used as best estimates to reduce bias. However, it is often time consuming to run process-based models (e.g. hydrological and crop models) in climate change impact studies using numerous climate scenarios. It would be interesting to investigate if using a reduced number of climate scenarios could lead to a reasonable estimate of the ensemble mean. In this study, we generated a single ensemble-mean climate scenario (En-WG scenario) using ensemble means of the change factors derived from 20 GCMs included in CMIP5 to perturb the parameters in a weather generator, LARS-WG, for selected locations across Canada. We used En-WG scenarios to drive crop growth models in DSSAT ver. 4.7 to simulate crop yields for canola and spring wheat under RCP4.5 and RCP8.5 emission scenarios. We evaluated the potential of using the En-WG scenarios to simulate crop yields by comparing them with crop yields simulated with the LARS-WG generated climate scenarios based on each of the 20 GCMs (WG scenarios). Our results showed that simulated crop yields using the En-WG scenarios were often close to the ensemble means of simulated crop yields using the 20 WG scenarios with a high probability of outperforming simulations based on a randomly selected GCM. Further studies are required, as the results of the proposed approach may be influenced by selected crop types, crop models, weather generators, and GCM ensembles.
Highlights
Climate change has significant impacts on various systems worldwide, including ecology, hydrology, and agriculture (IPCC 2014)
The long-term means of canola yields and spring wheat yields simulated using En-WG scenarios were compared with those using 20 WG scenarios for 2 future periods (2040−2069 and 2070−2099) under RCP4.5 and RCP8.5 in Figs. 2 & 3, respectively
Smaller ranges across the 20 WG scenarios at some locations may lead to a biased impression for the performance of the En-WG scenarios, as all individual members are relatively close to the ensemble means of the 20 WG scenarios when they are compared to locations with larger ranges
Summary
Climate change has significant impacts on various systems worldwide, including ecology, hydrology, and agriculture (IPCC 2014). Climate change impact assessments are essential to developing policies and strategies for climate change adaptation and mitigation. Climate change impact studies are often based on modelling results using future climate scenarios to drive impact models, such as hydrological models for water resources, crop growth models for crop produc-. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada. Authors and original publication must be credited
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