Climate change impact to Mackenzie river Basin projected by a regional climate model

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A regional climate model, WRF (Weather Research and Forecasting model), was set-up and fine-tuned to simulate the possible impacts of climate change to the Mackenzie River Basin (MRB) of Canada from May to October. The baseline (1979–2005) regional climate of the MRB simulated by WRF agrees well with gridded observed climate data, ANUSPLIN of Environment Canada. Next, WRF projected the regional climate change of MRB for 2041–2100 by dynamic downscaling RCP4.5 and RCP8.5 climate scenarios of three global climate models (GCMs), ACCESS1–3, CCSM4, and CanESM2. Based on RCP4.5 and RCP8.5 climate scenarios downscaled by WRF, air temperature of MRB is projected to increase by 2.5–3.8 °C and 4.5–6.9 °C in the 2050 s and 2080 s, respectively. In general, the air temperature of MRB is projected to increase marginally higher in colder regions of higher latitude and elevation. In contrast, the seasonal precipitation of MRB is only projected to increase marginally in the 2080 s under the RCP4.5 and RCP8.5 scenarios, respectively. The projected extreme precipitation indices show that future precipitation events would become more intensive and of longer durations. Under both RCP4.5 and RCP8.5 climate scenarios, the annual counts of days with total precipitation exceeding 10 mm of MRB (R10mm) are projected to increase by 18% in 2041–2100; the maximum 5-day precipitation (Rx5day) could increase by 9.4%. More studies should be conducted to gain a better understanding of the potential impacts of global warming to MRB and possible adaptive measures to mitigate these impacts.