Risk of water shortages in cities as early as the 2020s or 2030s

Two climatologists from the University of Pusan ​​(South Korea), Vecchia Ravinandrasana and Christian Franzke, simulated the risk of crises similar to the one experienced in Cape Town in 2018.

The South African metropolis saw its water reservoirs drop to alarming levels after three years of historic drought. It warned of the possibility of a "Day Zero" when water would no longer flow from the taps, a scenario ultimately averted thanks to the return of rain and restrictions.

"Many regions, including large [freshwater] reservoirs, could face a high risk of 'Drought Day Zero' during the 2020s and 2030s," the climate scientists write.

"Urban populations are particularly vulnerable," especially "around the Mediterranean, in southern Africa and in parts of North America," mainly in the western United States, they specify.

They cite Los Angeles as an example among "highly vulnerable" cities. India, northern China, and southern Australia are at lesser risk.

Projections estimate the number of people affected by 2100 at 753 million, more than a quarter of whom (196 million) will live in Mediterranean cities.

Two factors are behind this risk, according to the authors, "both anthropogenic climate change [due to human activities] and an increase in water consumption."

Climate change disrupts the planet's water cycle and distribution in many ways, including increased evaporation, less evenly distributed precipitation, and the drying up of rivers and natural water reserves.

Climate scientists stress "the urgent need for a response through proactive and targeted public policies, particularly in regions where rapid development, insufficient water infrastructure and climate vulnerability combine."