Exploring water use pathways under deep decarbonization scenarios in Canada at subnational scales using GCAM-Canada

Canada is a water rich country with annual per capita freshwater withdrawals that rank among the highest in the developed world. As global and national decarbonization efforts progress, the implications of these energy and land system transitions for Canadian water resources remain underexplored. This study employs the integrated assessment model, GCAM-Canada, to project Canadian water use to 2050 in six sectors - municipal, manufacturing, irrigation, livestock, primary energy mining and, thermal power generation - across provinces and river basins under six combinations of socio-economic and climate mitigation scenarios. The resulting water use projections elucidate the relative impacts of socio-economic development, technological change, carbon emission restrictions, and direct air capture (DAC) technologies on water use at subnational scales. Additionally, the study quantifies virtual water embodied in exported Canadian crops and electricity to assess the effects of global decarbonization on local water resources. Our findings project national withdrawals to decline by 9 %-26 % by 2050 in all scenarios, although patterns vary by province and river basin. Conversely, water consumption increases across all scales. Net-zero climate policies produce potential trade-offs and synergies with water use in different provinces, emphasizing the need for regional considerations in climate policy formulation. Green and blue virtual water exports are projected to increase in all scenarios, although to a lesser extent under decarbonization, while electricity sector virtual water exports are projected to increase under global net-zero scenarios with rising U.S. demand for Canadian hydropower. Our study emphasizes the need for tailored solutions within Canada's broader climate and water management frameworks for a more sustainable future.