Understanding the Effects of Climate Change on Extreme Weather: The 3 Main Takeaways

An innovative study has delved into the impact of climate change on severe heat and drought conditions, providing new knowledge for predicting and mitigating extreme weather phenomena. The researchers highlight an anticipated rise in the frequency and intensity of these events, especially under worst-case scenarios, emphasizing the importance of reducing emissions and adopting adaptation measures.

The study, led by Michael Mann, delves into how climate change can escalate extreme weather events like wildfires. In the most disastrous scenario, they predict significant increases in the scale, frequency, and duration of such occurrences.

Recently, the Proceedings of the National Academy of Sciences featured this study by Michael Mann, a professor in the Department of Earth and Environmental Science at the University of Pennsylvania’s School of Arts & Sciences, along with colleagues from Clemson University, the University of California Los Angeles, and Columbia University. Their research investigates how climate change can worsen simultaneous occurrences of heat and drought.

The results of this investigation could improve predictions of these interconnected weather phenomena and enrich understanding among scientists and policymakers. Ultimately, this can lead to more robust strategies for preventing and preparing for severe weather events.

Mann and his team sought to examine how the latest climate models, as used in recent assessment reports of the Intergovernmental Panel on Climate Change, handle episodes of heatwaves and droughts linked to some of the most destructive wildfires in recent history.

The goal was to understand the frequency, typical durations, and intensity of these events to improve forecasting and devise strategies for minimizing further damage to human life.

Researchers highlight the damaging impacts of intensifying droughts and wildfires in recent years. Mann points out two prominent examples – the 2020 California wildfires and the 2019–20 Australian bushfire season, which lasted nearly an entire year, dubbed the Black Summer. These episodes, known as compound drought and heat wave (CDHW) events, are characterized by long periods of high temperatures and water scarcity.

These conditions can coexist and exacerbate each other, potentially leading to heat-related illnesses and deaths, water scarcity for consumption and agriculture, reduced crop yields, elevated wildfire risks, and ecological stress. The study also asserts that human-induced climate change can heighten the frequency and intensity of these events.

In their comparison of a worst-case scenario and a moderate scenario, the researchers found that by the end of the 21st century, roughly 20% of global land areas could experience two CDHW events per year in a worst-case scenario. These events could persist for about 25 days, with a fourfold increase in severity. In contrast, the current average frequency of CDHW events is around 1.2 per year, lasting less than ten days and with much lesser severity.

The study predicts the regions most likely to experience the greatest increases in CDHW frequency by the end of the century include eastern North America, southeastern South America, Central Europe, East Africa, Central Asia, and northern Australia.

As climate change progresses, it becomes crucial to address the escalating risks linked to CDHW events. This research contributes to our growing understanding of the potential changes in CDHWs, underlining the need for preemptive actions such as emission reductions and adaptation strategies to protect vulnerable areas from the impacts of compound drought and heat wave events.

Mann concludes, “Our findings underscore the urgent need to transition away from fossil fuels as swiftly as possible to mitigate these dangerous combinations of heat and drought.”

This study, titled “Climate change will accelerate the high-end risk of compound drought and heatwave events” by Kumar P. Tripathy, Sourav Mukherjee, Ashok K. Mishra, Michael E. Mann and A. Park Williams, was published on 3 July 2023, in the Proceedings of the National Academy of Sciences and received funding from the National Science Foundation and the National Oceanic and Atmospheric Administration.

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• The Proceedings of the National Academy of Sciences
• Intergovernmental Panel on Climate Change
• University of Pennsylvania’s School of Arts & Sciences, Department of Earth and Environmental Science
• Clemson University
• University of California Los Angeles
• Columbia University
• National Science Foundation
• National Oceanic and Atmospheric Administration