Storyline analytical framework for understanding future severe low-water episodes and their consequences

Abstract

The 2021 drought highlighted the vulnerability of Quebec’s water resources and the potential for widespread consequences in a region that is generally perceived as having abundant water. This study uses a storyline approach to explore plausible future drought conditions for an event similar to what occurred in 2021 but under two different warming scenarios corresponding to increases of 2 and 3 °C in global surface temperatures compared to preindustrial levels. The storyline is constructed using a scenario-based approach, where analogues of the 2021 drought are derived from a large ensemble of regional climate simulations and combined with simulations produced by a hydrological model to offer a comprehensive understanding of both climate and hydrological conditions during and leading up to these potential future events. Results indicate a further deterioration in river conditions, particularly if a drought similar to that of 2021 were to be accompanied by a 3 °C rise in global temperature. In the hardest-hit areas of the province, low water levels could persist for a month longer, and river streamflow could drop by an additional 50 %, thus falling short of the threshold required to maintain the health of ecosystems for an extended period of time and resulting in significant impacts on ecosystems and human activities. By linking future river conditions to a real event that affected southern Quebec, storyline approaches have the potential to facilitate discussions on the impacts of climate change on water deficits in the region, particularly in cases where those impact-inducing thresholds are not well understood.