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In recent years, the frequency and intensity of extreme temperature events have escalated, posing unprecedented challenges to ecosystems, economies, and human health. As global temperatures rise, these events are emerging as critical threats; therefore, understanding their changes is essential for developing strategies to mitigate their growing risks under global warming. In this study, we used ETCCDI (Expert Team on Climate Change Detection, Monitoring, and Indices) temperature indices to analyze future changes in extreme temperature events in the South Saskatchewan River Watershed (SSRW) in Southern Alberta, Canada, a critical area for irrigation, agriculture, and food production. This analysis is based on an ensemble of 26 Global Circulation Models (GCMs) and three Shared Socio-economic Pathway (SSP) scenarios, in three periods (2015–2030, 2041–2060, 2071–2100), compared against the base period of 1951–1990. The results suggest substantial changes in most of the studied indices towards higher temperatures, with a significant rise in both the numbers of days with extreme temperatures and the magnitude of the temperature itself, as well as a notable drop in the number of cold days. As a result of warming, the growing season length is 16 days longer in 2015–2030 compared to the base period and is projected to increase substantially by the end of the century. A longer growing season might seem favourable for agriculture, but it can disrupt water availability and cause unpleasant environmental consequences. Overall, the scenarios considered in this research suggest that the SSRW could experience warming at a significant rate. This finding underscores the urgent need for adaptation and mitigation actions to enhance resilience and sustainability. [ABSTRACT FROM AUTHOR]

In this study, a CMIP6 ensemble of 26 GCMs and SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios from CanDCS-U6 is used to project drought conditions in the South Saskatchewan River Watershed. The near-current period (2015–2030) and two future periods (2041–2060 and 2071–2100) are analyzed based on the Standardized Precipitation Evapotranspiration Index (SPEI) at 1-, 3-, 6-, 12-, and 24-month timescales. Projections indicate a shift in average SPEI values from above zero (no drought) in the base period (1951–1990) to more negative values in the future. Results show an increase in drought severity and frequency under climate change conditions. The percentage of time with no drought conditions is projected to decline from 55–70% in the base period to 25–45% by 2071–2100. Severe and extreme droughts, rare in the base period (below 4%), are projected to increase to up to 19% by 2071–2100. The area experiencing drought is expected to expand from 36–49% (for different SPEI timescales) in the base period to up to 76% by 2071–2100. Drought frequency is projected to be higher under SSP1-2.6 and less frequent under SSP2-4.5. Results showed that longer SPEI timescales are associated with higher drought occurrence rates and severity. The spatial pattern of drought is also projected to significantly change, with higher frequencies expected in the eastern parts of the watershed under climate change. [ABSTRACT FROM AUTHOR]