Quantifying the uncertainty introduced by internal climate variability in projections of Canadian crop production
Qian, B., Jing, Q., Smith, W., Grant, B., Cannon, A.J., Zhang, X. (2020). Quantifying the uncertainty introduced by internal climate variability in projections of Canadian crop production. Environmental Research Letters, [online] 15(7), http://dx.doi.org/10.1088/1748-9326/ab88fc
Plain language summary
Internal climate variability is one of the major sources of uncertainty in climate projections. Internal climate variability is typically referred to as the variations resulting from the chaotic nature of the climate system without external forcings. However, the uncertainty due to internal climate variability is seldom quantified for projections of crop production. In this study, we focuses on quantifying the uncertainty related to internal climate variability in projections of crop productions in Canada at the global warming levels of 1.5 °C, 2.0 °C, 2.5 °C and 3.0 °C. Crop simulation models were driven by climate scenarios from large ensembles of two Canadian climate models and a multi-model ensemble of 20 climate models from world’s leading climate modelling centres. Our results indicate a need to account for uncertainty related to internal climate variability in projections of Canadian crop production, especially at lower warming levels.
Internal climate variability (ICV) is one of the major sources of uncertainty in climate projections, yet it is seldom quantified for projections of crop production. Our study focuses on quantifying the uncertainty due to ICV in projections of crop productions in Canada. We utilize climate scenarios from two large ensembles (LEs, CanESM2-LE and CanRCM4-LE with 25 members each) as inputs to the crop models in the Decision Support System for Agrotechnology Transfer. We simulate crop yields for canola, maize and spring wheat under the future climates of four global warming levels. The coefficient of variation (CV) of the projected crop production across the LE members is used to quantify the uncertainty related to ICV and this is compared with the CVs generated using the 20 GCMs in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Crop production in Canada could increase with global warming, e.g. spring wheat production could increase by up to 21% at the warming level of 3.0 °C. The projections often produce larger uncertainty associated with the GCMs than from ICV at all warming levels above 2.0 °C. The results from an asymptotic test for the equality of CVs show a significant difference in CVs of projections of canola production between CanESM2-LE/CanRCM4-LE and CMIP5 for the warming level of 3.0 °C. However, the test results do not indicate a significant difference among the ensembles at all four warming levels for maize and spring wheat. The uncertainty due to ICV is often comparable to that associated with GCMs at the warming level of 1.5 °C, e.g. a CV of 6.0 and 6.4% for CanESM2-LE and CanRCM4-LE and 6.6% for CMIP5 in the projections of spring wheat production. We conclude there is a need to account for uncertainty related to ICV in projections of Canadian crop production, especially at lower warming levels.