Warming soil temperature and increasing baseflow in response to recent
and potential future climate change across northern Manitoba, Canada
Abstract
This study investigates the impacts of climate change on the hydrology
and soil thermal regime of ten sub-arctic watersheds (northern Manitoba,
Canada) using the Variable Infiltration Capacity (VIC) model. We utilize
statistically downscaled and bias-corrected forcing datasets based on 17
general circulation model (GCM) - representative concentration pathways
(RCP) scenarios from phase 5 of the Coupled Model Intercomparison
Project (CMIP5) to run the VIC model for three 30-year periods: a
historical baseline (1981–2010), and future projections (2021–2050:
2030s and 2041–2070: 2050s), under representative concentration
pathways (RCPs) 4.5 and 8.5. The CMIP5 Multi-Model Ensemble (MME)
mean-based VIC simulations indicate a 15–20% increase and 10%
decrease in the projected annual precipitation and snowfall,
respectively over the southern portion of the basin and
>20% rainfall increase over the higher latitudes of the
domain by the 2050s. Snow accumulation is projected to decline across
all sub-basins, particularly in the lower latitudes. Projected
uncertainties in major water balance components (i.e.,
evapotranspiration, surface runoff, and streamflow) are more substantial
in the wetland and lake-dominated Grass and Gunisao watersheds than
their eight counterparts. Future warming increases soil temperatures
>2.5°C by the 2050s, resulting in 40–50% more baseflow.
Further analyses of soil temperature trends at three different depths
show the most pronounced warming in the top soil layer (1.6°C 30-year-1
in the 2050s), whereas baseflow increases substantially by 19.7% and
46.3% during the 2030s and 2050s, respectively. These results provide
crucial information on the potential future impacts of warming soil
temperatures on the hydrology of sub-arctic watersheds in north-central
Canada and similar hydro-climatic regimes.