Increased drought and severe storms in Southern Alberta

Southern Alberta is experiencing a shift in climate patterns, with increased droughts and more severe hailstorms causing significant agricultural and property damage.

Having lived in Calgary for 26 years and my parents for 45, we have noticed deviations from Southern Albertas climate patterns. Summers have been noticeably drier, with prolonged periods of drought putting immense strain on the agricultural industry and urban areas (Alberta WaterPortal, 2024). 2021 was one of the harshest droughts in Alberta, leading to intense grassfires, wildfires, and agricultural destruction affecting the livelihoods of people, indigenous communities, and communities (Alberta WaterPortal, 2024; CBC, 2021; CBC, 2022). The small flash floods that cool the summer evenings have evolved into hailstorms that devastate communities, with the 2020, 2021, and 2024 hailstorms in Calgary costing $1.2 billion, $700 million, and $2.8 billion dollars of damages, respectively (Insurance Bureau of Canada, 2024). Since the 1970s, crop loss due to hail has progressively increased in Southern Alberta as well (Mohamed et al., 2024). This is tied with the increasing frequency of hail storms in the region with increasing year-to-year variability as well (Etkin & York University, 2018). It is estimated that for every one degree Celsius of warming, there is a 40% increase in hail damage (Fernandes et al., 2011).

The potential factors behind these climatic changes are likely due to both local and global processes. Locally, the increased temperatures are leading to higher evaporation rates and diminished snowpacks, leading to increased drought conditions. The loss of albedo from glaciers and snowpacks is likely leading to increased surface temperatures and evaporation as well (Shea et al., 2005). Furthermore, warmer temperatures allow the atmosphere to hold more moisture, thus facilitating stronger storms such as hail. The increasing surface temperatures in the region can also increase atmospheric moisture demand and likely alter atmospheric circulation patterns, contributing to droughts and turning regular summer rain into severe storm systems that are more damaging (Dai, 2010).

Global climate patterns, such as El Nino and the occurrence of sea surface temperature anomalies, are also likely to play a part in triggering short-term drought conditions in the area (Dai, 2010). Additionally, the rise in greenhouse gas emissions has exacerbated extreme weather events, including more frequent and intense hailstorms. These changes correspond with global climate models that estimate more extreme variability in weather events as the planet warms (Huber et al., 2011). In Alberta, this has taken the form of hot and dry summers paired with severe hailstorms mirroring natural disasters.

After consultation with the team at the at the Northern Hail Project (NHP), they provided additional information. With climate change affecting Southern Alberta, the NHP team projected increased hail damage potential in the spring and at high latitudes (Brimelow et al., 2017; City of Calgary, 2024). Regions with drier and cooler climates, such as Southern Alberta, are predicted to see both an increase in energy and the size of the hail, particularly in the early summers (Brimelow et al., 2017).

This is due to increased surface temperatures allowing the atmosphere to hold more moisture, thus increasing its convective available potential energy (Diffenbaugh et al., 2013). This increased energy in the atmosphere can lead to more intense updrafts, leading to unstable atmospheres and more powerful storms such as the formation of large hail (Diffenbaugh et al., 2013). Secondly, an increase in low-level wind shear strengthens updrafts, which allows storms to organize and persist longer, increasing the likelihood of hail formation (Diffenbaugh et al., 2013).

References: Alberta WaterPortal. (2024). Drought in 21st century Alberta. https://albertawater.com/history-of-drought-in-alberta/drought-in-21st-century-alberta/

Brimelow, J. C., Burrows, W. R., & Hanesiak, J. M. (2017). The changing hail threat over North America in response to anthropogenic climate change. Nature Climate Change, 7(7), 516–522. https://doi.org/10.1038/nclimate3321

CBC. (2022). Severity and sweep of Prairie droughts could spiral as climate changes. https://www.cbc.ca/news/canada/edmonton/severity-and-sweep-of-prairie-droughts-could-spiral-as-climate-changes-1.6391982

CBC. (2021). Western Canada heat wave expected to break daily, all-time temperature records. https://www.cbc.ca/news/canada/british-columbia/western-canada-heatwave-1.6081519

City of Calgary. (2024). Climate Projections for Calgary. https://www.calgary.ca/environment/policies/climate-risk-assessment-framework.html

Dai, A. (2010). Drought under global warming: A review. Wiley Interdisciplinary Reviews Climate Change, 2(1), 45–65. https://doi.org/10.1002/wcc.81

Diffenbaugh, N. S., Scherer, M., & Trapp, R. J. (2013). Robust increases in severe thunderstorm environments in response to greenhouse forcing. Proceedings of the National Academy of Sciences, 110(41), 16361–16366. https://doi.org/10.1073/pnas.1307758110

Etkin, D. & York University. (2018). Hail Climatology for Canada: An update. Institute for Catastrophic Loss Reduction. https://www.iclr.org/wp-content/uploads/2018/03/hail-climatology-for-canada-an-update.pdf

Huber, D. G., Gulledge, J., & Center for Climate and Energy Solutions. (2011). Extreme weather & climate change: Understanding the link and managing the risk. In Center for Climate and Energy Solutions. https://patarnott.com/atms790/pdf_atms790/papers2022/ExtemeWeatherAndClimate.pdf

Insurance Bureau of Canada. (2024). August hailstorm in Calgary results in nearly $2.8 billion dollars in insured damages. https://www.ibc.ca/news-insights/news/august-hailstorm-in-calgary-results-in-nearly-2-8-billion-in-insured-damage

Mohamed, I., Najafi, M. R., Joe, P., & Brimelow, J. (2024). Multivariate analysis of compound hail, wind and rainfall extremes in Alberta’s hail alley. Weather and Climate Extremes, 100718. https://doi.org/10.1016/j.wace.2024.100718

Shea, J., Anslow, F., & Marshall, S. (2005). Hydrometeorological relationships on Haig Glacier, Alberta, Canada. Annals of Glaciology, 40, 52–60. https://doi.org/10.3189/172756405781813465