High-Resolution Regional Climate Projections for Ontario and the Canadian Great Lakes Basins

The IPCC-endorsed multiple model/scenario approach and a state-of-the-science combined downscaling methodology were applied to project the future climate changes over Ontario and the Canadian Great Lakes basins. Significant warming is expected across the province under all RCPs. Relative to 1986–2005 averages, the highest temperature rise is projected to occur in Ontario’s Far North, 7.3°C warmer by the 2080s. The temperature over the Great Lakes Basin is projected to increase by 1.3–5.7°C. Ontario’s annual total precipitation is projected to increase 86.9 mm (11%) by the 2080s under RCP 8.5, while summer precipitation is projected to decrease by 32.9 mm (12%) and winter precipitation to increase by 52.4 mm (48%). In the Great Lakes Basin, the greatest increase in annual average temperature (1.7–5.3°C) is projected to occur in the Lake Superior sub-basin by the 2080s. Winter warming is projected to exceed summer warming in all sub-basins. Annual total precipitation is projected to increase in all five sub-basins, with the largest increase in the Lake Superior sub-basin. Summer (winter) is projected to be drier (wetter) across the entire Great Lakes Basin. These projected changes could have implications on future water levels in the Great Lakes and many aspects over the study area