University of Bristol-Led Study Warns Global Megacities Face Escalating Flood and Drought Risks Amid Climate Extremes

University of Bristol-Led Study Warns Global Megacities Face Escalating Flood and Drought Risks Amid Climate Extremes

(IN BRIEF) A new study led by WaterAid, in collaboration with researchers from the University of Bristol and Cardiff University, reveals that the world’s 100 most populous cities are increasingly vulnerable to both flooding and drought due to climate change. The report finds that nearly 17% of these cities are experiencing rapid transitions between floods and droughts, while 20% are undergoing major shifts between extreme wet and dry conditions. European cities, including Madrid and London, are showing significant drying trends, and cities in Africa and Asia are facing severe challenges in water security. The study underscores the need to address social and infrastructure vulnerabilities and calls for global collaboration and investment to build resilience against escalating climate hazards.

(PRESS RELEASE) BRISTOL, 13-Mar-2025 — /EuropaWire/ — A recent report has shed light on the growing vulnerability of the world’s 100 most populous cities to both flooding and drought. Conducted by WaterAid in collaboration with academics from the University of Bristol and Cardiff University, the study highlights significant climate shifts affecting urban areas. European cities, for instance, are experiencing notable drying trends, with Madrid ranking as the second most affected among 49 drying cities and London positioned at 44th. Meanwhile, cities in Africa and Asia face severe threats from extreme climate events that jeopardize access to clean water and overall water security.

The report reveals that nearly 17% of these cities are undergoing ‘climate whiplash’ – a pattern of alternating extreme floods and droughts – while 20% have experienced major shifts from one extreme to the other, termed ‘climate hazard flips.’ Co-lead scientist, Professor Katerina Michaelides of the University of Bristol, emphasized that the study underscores the unique and varied manifestations of climate change across different regions. All the European cities examined have shown drying trends over the past 42 years, which could lead to prolonged drought conditions.

In addition to assessing climate hazards, the research evaluated each city’s social and water infrastructure vulnerabilities, ranging from poverty to inadequate water and waste systems. This dual approach highlights the compounded risk faced by over 250 million urban residents in locations such as Kano, Bogota, and Cairo. Dr Sean Fox from the University of Bristol noted that the impact of climate-related disasters is not solely determined by their frequency but also by the preparedness of communities to cope with such events.

The study identifies two major hotspots of risk: south and southeast Asia, and north and east Africa. Cities such as Khartoum, Faisalabad, Lahore, Baghdad, Surabaya, Nairobi, and Addis Ababa are among the most vulnerable. European cities like Barcelona, Berlin, and Paris are also at increased risk due to aging water and waste infrastructures. Professor Michael Singer of Cardiff University pointed out that these widespread climate hazard trends underscore the need for regional cooperation to build resilience against emerging challenges.

With water-related disasters, including floods and droughts, having quadrupled over the past 50 years, WaterAid is urging global leaders, multilateral banks, and the private sector to invest in robust systems that can withstand extreme weather events and secure essential water access. Tim Wainwright, Chief Executive of WaterAid UK, called on the UK to lead by example in addressing these pressing global challenges.

For further details, please refer to the paper titled “Water and Climate: Rising Risks for Urban Populations.”

Further information about WaterAid: WaterAid is a global nonprofit organization dedicated to ensuring that everyone, everywhere has access to clean water, decent toilets, and proper hygiene, working in 22 countries to transform lives.

About WaterAid

WaterAid is an international not-for-profit determined to make clean water, decent toilets and good hygiene normal for everyone, everywhere within a generation. We work alongside communities in 22 countries to secure these three essentials that transform people’s lives. Since 1981, WaterAid UK and its Country Programmes have reached 29 million people with clean water and 29 million people with decent toilets.

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SOURCE: University of Bristol