Sudden climate changes are spreading and affecting the world's most populated cities.

BarcelonaThe climate in some of the world's most populated cities is experiencing abrupt changes, shifting from droughts to floods and vice versa, and rising temperatures are destabilizing the global water cycle, according to a report by the NGO WaterAid. The organization highlights a climate phenomenon known as climate whiplash, Sudden, extreme climate changes that alternate prolonged periods of drought with intense rainfall and flooding. This phenomenon is spreading worldwide, with varying degrees of impact across cities and regions.

The WaterAid organization, which has analyzed the climate of the last four decades in 112 cities around the world, explains that the trend is global, but that climate changes are different depending on the area of the world. Drought affects Europe, the Arabian Peninsula region and much of the United States the most, while South and Southeast Asia experience increasingly intense rainfall.

Cities such as Dallas, Jakarta, Madrid, Nairobi, Riyadh, Melbourne and dozens more have suffered a "climate turn" in the last twenty years and have gone from extremely dry climates to humid ones or vice versa.

"Our study shows that climate change is dramatically different around the world," according to Professor and co-author of the study Katerina Michaelides, of the University of Bristol in the United Kingdom, in statements to The Guardian. The other co-author, Professor Michael Singer of Cardiff University, describes the pattern as "global weirding", A strange global warming. "There will be winners and losers from climate change; it's already happening," the professor adds to Reuters.

But who is to blame? The report is clear. Global warming, driven by fossil fuel pollution, and whose consequences are the fault of humans.

When temperatures rise, the air warms up and has the capacity to retain more water vapor. This means it can absorb more moisture from the environment. During periods of heat and dryness, the air draws more water from the ground, worsening droughts. When rain comes, the warm air, which has accumulated a lot of water vapor, can quickly release a large amount in the form of more intense precipitation.

"Now is the time to act"

"Most of the cities we analyzed are changing in some way, but not always in predictable ways," Singer says. "And given that we're looking at the world's largest cities, this affects a really significant number of people," he says.

The population of these cities can be severely affected by floods and droughts, reduced access to clean water and food, power outages, the spread of disease, and forced displacement from their cities. The effects are even more severe in cities with poor water infrastructure, the report says.

Adapting to these sudden climate changes is extremely difficult. According to the study, overall, it's a huge challenge because those cities that do have water supply and flood protection infrastructure are often old and responding to a climate that no longer exists. In other countries, especially low-income ones, even minimal infrastructure doesn't exist.

"The threat of a day zero "Global disaster is becoming more and more imminent," WaterAid Executive Director Sol Oyuela told the British newspaper. "Now is the time to act collectively with urgency, so that communities can recover from disasters and be prepared for the future."