Peshawar in Pakistan has flipped from a generally drier weather to extreme damp conditions © Arif Ali/AFP/Getty ImagesMore than half of the world’s most crowded cities are getting wetter, according to new research on how water patterns are undergoing extraordinary shifts in metropolitan areas as climate change intensifies the ambient effects. The scientific study involving Bristol and Cardiff institutions, on behalf of support group WaterAid, found that 52 per share of towns showed a drier pattern over the past four decades, including Colombo, Mumbai and Kuala Lumpur. At the same time, some 44 per share of urban areas were getting drier, including Los Angeles, Riyadh, Paris and Cairo. Scientists say climate change is leading to more severe rainfall, as every level of heat of the environment means it has the capacity to carry 7 per cent more liquid. Similarly, water is evaporating from the floor because of hotter temperatures, with some places” seeing a large drying impact”, said Katerina Michaelides, lead scientist from the University of Bristol. The “huge variability” in water patterns around the world made anticipating the effects a big challenge, she said. “]Cities are ] all changing in different ways. And so that the challenges that each city is facing are completely different and therefore would require a bespoke approach”, she said. South Asian cities had made the most dramatic flip from drier to flood conditions. The study showed about 13 per cent of cities had flipped from a historically drier climate to extreme wet conditions, including Lahore in Pakistan and Bogotá in Colombia. By contrast, cities such as Madrid and Hong Kong were among the 7 per cent of big urban areas in the study that had shifted from a wetter to an extremely dry climate. Europe’s ageing infrastructure meant many of the continent’s cities were increasingly vulnerable to the weather extremes. However, it was the poorer cities across Asia and Africa that were most at risk from climate shifts, hitting access to clean water in urban areas already struggling with development challenges. The study estimated one quarter of a billion people lived in cities that had shifted from one extreme to the other over the past 40 years, posing huge risks for urban populations and amplifying concerns about access to clean water. ” Climate whiplash” was experienced by 15 per cent of the world’s 100 most populous cities, including Hangzhou in China and Jakarta in Indonesia, as a result of an intensification of both droughts and floods. Past research has found that weather-related disasters such as flooding and drought have increased by 400 per cent in the last 50 years, with 90 per cent of climate disasters driven by either too little or too much water. Sol Oyuela, WaterAid’s executive director of global policy and campaigns, said four billion people globally already faced water scarcity. The group has long warned of the consequences of so-called Day Zero — where a city runs out of water— which could push economies and security” to the brink”. Climate CapitalWhere climate change meets business, markets and politics. Explore the FT’s coverage here. Are you curious about the FT’s environmental sustainability commitments? Find out more about our science-based targets here
More than half of country’s most populated places are getting drier, research finds
