Proxy versus Modelled Hydrology, Saskatchewan and Athabasca River Basins
In western Canada, internal natural variability is the dominant source of uncertainty for the climate model projection of precipitation and related variables. Tree-ring records capture this natural variability and also enable testing of the capacity of climate models to simulate significant modes of variability. We compare millennial tree-ring reconstructions of the weekly flows of the Athabasca and North Saskatchewan Rivers to weekly flows from a hydrological model forced with climatology from various runs of CMIP6 Earth System Models. Relative to the proxy streamflow time series, the climate / hydrological models have a high-frequency bias and underestimate decadal scale hydroclimatic variability. Inter-annual to decadal variability represent more of challenge for water resource management than incremental slow-onset changes in water yield resulting from the regional impacts of global climate change.