image: View of Cape Town from the top of Table Mountain, February 2017. view more
Credit: Image credit: Amy S. Porter (photographer).
The probability of another "Day Zero" drought in Cape Town, South Africa will increase by the year 2100 due to anthropogenic emissions, a study suggests. In 2018, after a three-year rainfall deficit, Cape Town's municipal water supply was nearly depleted, known as the "Day Zero" drought. Salvatore Pascal and colleagues quantified the likelihood of similar droughts happening in future decades as the climate warms. To increase the resolution of the analysis for a small regional area and to account for rainfall variability, the authors used a high-resolution, large-scale ensemble of historical data to estimate the contribution of anthropogenic climate change to future droughts. The authors found that the 2018 drought was made 5-6 times more likely by anthropogenic climate forcing, as compared to natural forcing, such as by volcanoes. Modeling two future emissions scenarios, the authors found that the likelihood of another "Day Zero" drought increased from 0.7% to 25% by 2100 under an intermediate emission scenario. Under a high-emission scenario, the likelihood increased to 20% by 2045 and to 80% by the end of the century. According the authors, the analysis could be applied to other arid regions with variable rainfall to determine emerging drought risk.
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ARTICLE #20-09144: "Increasing risk of another Cape Town "Day Zero" drought in the 21st century," by Salvatore Pascale, Sarah B. Kapnick, Thomas L. Delworth, and William F. Cooke.
MEDIA CONTACT: Salvatore Pascale, Stanford University, CA; e-mail: <pascaledeep@gmail.com>
Journal
Proceedings of the National Academy of Sciences