The role of climate change in the 2015-2017 drought in the Western Cape of South Africa

An international team of scientists used a multi-method attribution approach to determine that anthropogenic climate change increased the likelihood of the 2015-2017 Western Cape drought by a factor of 3.3. The drought, characterized by three consecutive years of below-average rainfall, led to a severe water crisis in Cape Town, nearly resulting in 'day zero'. The study finds that drought risk in this region scales linearly with warming, suggesting that further temperature increases will continue to raise the probability of such extreme events.

• Anthropogenic climate change significantly increased the probability of the 2015-2017 drought occurring in the Western Cape. By synthesizing observational analysis and multiple climate models, the study calculates that the likelihood of such an event increased by a factor of 3.3 (ranging from 1.4 to 6.4).
• The 2015-2017 drought was the most severe since 1904, driven primarily by a deficit in rainfall rather than increased evaporation from high temperatures. Specifically, the region experienced 30% to 50% below-average rainfall over three years, with the most significant anomalies occurring during the shoulder seasons of March-May and August-October.
• The drought caused an acute water shortage in Cape Town, which serves approximately 3.7 million residents. The crisis reached a point in early 2018 where the city was expected to run out of water, a scenario termed "day zero", in March 2018.
• Future projections indicate that drought risk in the Western Cape scales linearly with global warming. Models suggest that if global mean surface air temperature increases to 2°C above pre-industrial levels (approximately 1°C warmer than today), the probability ratio of such droughts will increase further by a factor comparable to the increase seen up to the present.
• The Western Cape Water Supply System, comprising 14 dams and pipelines, is highly vulnerable because it depends almost entirely on rainfall. While designed to withstand droughts with a 1-in-50-year return interval, climate change has shifted the return time of extreme droughts, making the system and its users more vulnerable than previously planned for.

APA

World Weather Attribution (2018). The role of climate change in the 2015-2017 drought in the Western Cape of South Africa. https://www.worldweatherattribution.org/the-role-of-climate-change-in-the-2015-2017-drought-in-the-western-cape-of-south-africa/

Chicago

World Weather Attribution. The role of climate change in the 2015-2017 drought in the Western Cape of South Africa. 2018. https://www.worldweatherattribution.org/the-role-of-climate-change-in-the-2015-2017-drought-in-the-western-cape-of-south-africa/.

Wikipedia

{{cite report |author=World Weather Attribution |title=The role of climate change in the 2015-2017 drought in the Western Cape of South Africa |date=13 July 2018 |url=https://www.worldweatherattribution.org/the-role-of-climate-change-in-the-2015-2017-drought-in-the-western-cape-of-south-africa/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{worldweatherattribution2018role, author = {{World Weather Attribution}}, title = {{The role of climate change in the 2015-2017 drought in the Western Cape of South Africa}}, institution = {World Weather Attribution}, year = {2018}, month = jul, url = {https://www.worldweatherattribution.org/the-role-of-climate-change-in-the-2015-2017-drought-in-the-western-cape-of-south-africa/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }