The world’s 100 most populated cities are becoming increasingly exposed to floods and droughts, new research has found.
Charity WaterAid has warned that 90% of all climate disasters are driven by too much or too little water, and that weather-related disasters have increased by 400% in the last 50 years.
Its study, developed with academics from University of Bristol and Cardiff University, compared each city’s social and water infrastructure vulnerabilities – such as poverty and waste systems – alongside more than 40 years worth of new data on climate hazards.
With this, the researchers identify which cities and communities worldwide could be the most vulnerable to extreme climate changes and the least equipped to handle them.
The analysis, released on Wednesday, found that 17% of the cities studied are experiencing “climate whiplash”, where both droughts and floods are intensifying.
It also showed that 20% of the cities have seen a major flip, previously experiencing one extreme and now increasingly facing the other.
For example, southern Asian cities are now shifting toward a more extreme wet climate, becoming increasingly flood-prone, whereas European cities are flipping towards a more extreme dry climate.
London, Madrid and Paris are among those that have seen this drying trend over the last four decades, according to the study, which warned that the region could face more frequent and long-lasting droughts as a consequence.
Meanwhile, Colombo in Sri Lanka, and Faisalabad and Lahore in Pakistan are seeing the most dramatic flip from historically dry conditions to becoming severely flood-prone.
Overall, the report said cities across Africa and Asia are emerging as the most at-risk of extreme climate shifts, causing devastating impacts on access to clean water for urban communities on the front line of global warming.
But WaterAid said that the increased exposure to floods and drought globally is putting major pressure on vital water access and sanitation systems, making it harder for communities and economies to prepare for, recover from, and adapt to climate change.
The charity is urging the British Government to upholds its foreign aid commitments and its current international climate finance commitments and invest a third of its adaptation budget in water action.
It also called on the Foreign Office to launch an international water security strategy and feature action on the water crisis across all areas of foreign policy.
Tim Wainwright, WaterAid UK’s chief executive, said: “This research comes at a pivotal time, as we’re seeing a sweep of global aid cuts, which could leave basic human rights hanging in the balance.
“Floods and droughts are stripping away people’s foundation of survival – water.
“But with a reliable supply of clean water, communities can recover from disasters, stay healthy, and be ready for whatever the future holds. It all starts with clean water.”
The charity is working with partners globally to tackle the impacts of climate change on water, with solutions like harvesting rainwater, monitoring water levels and installing toilets designed to withstand floods.
But the organisation urged global decision makers to prioritise and invest in key solutions that strengthen community resilience against extreme weather.
Mr Wainwright said: “We urge the UK to show leadership and maintain its influential role in tackling global climate and health challenges – essential to creating a secure world free from poverty.”
Professor Katerina Michaelides, lead scientist from University of Bristol, said: “The findings from our study illustrate just how differently and dramatically climate change is expressing around the globe – there is no one-size-fits-all.
“A deeper understanding of localized climate hazards can support more intelligent and bespoke planning in major cities.”
Professor Michael Singer, lead scientist from Cardiff University, added: “One interesting outcome of this study is how many of the climate hazard trends appear to spread over broad regions, suggesting that there may be significant adaptation challenges to new hazard regimes, but also regional opportunities for collaboration between nations to become more resilient to climate change in urban centres.”
The PA news agency has contacted the Foreign Office for comment.