Yves here. Yours truly has been under-reporting in Links the number and severity of bad climate change effect stories, since if I did merely a pretty good job, they would eat up all of Links. On top of record heat stories from every reasonably populated continent (including record daily minimum), flooding, droughts, and knock-ons (poor harvests, increased pathogen and pest levels), one regular category is cities running short of water. Cape Town was an early victim but it now has plenty of company.

This story discusses first-level responses, which is rationing and harvesting rainwater. But what comes next? For instance, in California, which has been subject to droughts, the main line of attack has been household use, when agriculture greatly exceeds that, and a lot of that is profligately wasteful like growing rice. So even these initial responses are hamstrung by political interests.

By Tanya Petach, the Climate Science Fellow at the Aspen Global Change Institute and Kaitlin Sullivan, a freelance journalist who covers health, science, and the environment. Produced in partnership with Energy Innovation and the Aspen Global Change Institute. Originally published at Yale Climate Connections, their content-sharing partner

In April 2024, more than 9 million residents of Bogotá, Colombia’s capital city, were told to collect rainwater – if the city was lucky enough to experience a storm.

Fed by the Guatiquía River, the Chingaza reservoir system, which supplies the area with 70% of its water, had reached critically low levels.

To make what was left stretch through a dry spell with no clear end in sight, authorities divided the city into nine zones. Every day, one of the zones would go dry for 24 hours. No toilet would flush. No glass of water would be filled from the tap. Dishes would have to go unwashed.

Bogotá Mayor Carlos Galan told residents they should be prepared to live with the water restrictions for a year.

“The call is to take care of every drop of water,” the mayor’s office said, according to CBS News.

A month later, 2,000 miles away in Mexico, the Cutzamala system of reservoirs reached historic lows. The water reserves supply a substantial portion of water to Mexico City’s 22 million residents, who faced mandatory rationing.

Bogotá and Mexico City’s stories mirror those of cities across the globe. The amount of water stored in lakes worldwide has drastically and steadily decreased since 1992, according to a 2023 study published in the prestigious research journal Science. During those 30 years, freshwater lakes collectively lost an average of 600 cubic kilometers of water storage annually – 17 times the volume of Lake Mead, the largest reservoir in the United States.

A Global Crisis

The cause is a combination of human-caused overuse and unprecedented shifts in the climate, the researchers found.

Increasing temperatures, accelerated evaporation, and unpredictable shifts in rain and snow patterns and the runoff these events create have made urban water sources increasingly unstable.

These factors, coupled with unsustainable water consumption, are responsible for about half the water losses over the last 30 years. They’ve pushed cities around the globe closer to Day Zero, when water supply would be depleted and taps would run dry.

But understanding which of these stressors is having the biggest impact on each water system is the cornerstone for creating solutions.

The Cautionary Tale of the Aral Sea

In living memory, the Aral Sea, which straddles the Uzbekistan-Kazakhstan border, was the fourth-largest lake in the world.

Engineers diverted massive amounts of water from the Aral Sea starting in the early 1960s to irrigate one of the world’s largest cotton farming operations. The lake rapidly shrank over the next three decades.

That decision made the Aral Sea a poster child for what happens when humans overuse water in arid regions.

This entry was posted in Doomsday scenarios, Environment, Global warming, Guest Post on by Yves Smith.