You might not believe it if you've experienced one of the flash floods hammering the planet from Texas to Vietnam this summer, but the Earth is becoming drier — at least the parts where most people live. Given how this can affect every aspect of human existence, from farming to geopolitics, it’s past time we started treating this like the emergency it is.

Measurements from NASA’s Gravity Recovery and Climate Experiment satellites suggest the continents have been losing fresh water at an alarming rate since 2002, according to a recent study in the journal Science Advances.

Some parts of the planet are becoming wetter, especially in the tropics, but the drying parts are drying more quickly than the increasingly wet parts are getting wet. The drying parts are also spreading, gaining roughly two Californias’ worth of land every year and recently merging into “mega-drying” regions sprawling across vast stretches of continents.

One of these mega-drying regions starts in Alaska and covers much of Canada, from British Columbia to Manitoba. Another encompasses the U.S. Southwest and Central America. The largest covers three continents, from the British Isles, Europe and North Africa in the west all the way to China and Malaysia in the east. Three-quarters of the global population, or about 6 billion people, live in areas where fresh water has dwindled since 2002.

“Fresh water is finite, and we’re losing it,” Hrishikesh Chandanpurkar, a research scientist with Arizona State University and the paper’s lead author, told me. Much of the water ends up in the salty oceans, contributing more to sea-level rise than the melting of ice in Antarctica or Greenland.

Alarmingly, this trend accelerated after the 2014 El Niño event, the strongest on record, drove global temperatures higher by warming the water in the eastern Pacific. Since then, the global surface area experiencing drying extremes at any given moment has grown by about six Californias per year — despite the Earth spending most of that time in La Niña conditions, when water in the eastern Pacific is cooler. That suggests 2014 may have been a tipping point beyond which returning to normal wet-dry cycles may be impossible on human timescales.

That’s partly because most of the Earth’s drying places are historically arid anyway, Chandanpurkar explained. When they suffer extremes of drought, they tap already precious groundwater, which can take millennia to refill.

The American Southwest, in the throes of a decades-long megadrought, is a prime example. GRACE satellite data show the lower Colorado River basin — which includes parts of Arizona, California, Nevada and Mexico — has lost one Lake Mead’s worth of water, or about 28 million acre-feet, since 2003, according to a separate study earlier this year to which Chandanpurkar contributed. (An acre-foot is how much it takes to fill an acre with a foot of water.)

Climate change plays a big role here by making droughts longer and more severe and by sucking the water out of the ground through evaporation. But as with most other climate-related catastrophes, human behavior makes everything worse. In fact, the biggest factor in continental drying is groundwater loss, the study found — the primary driver of which is our own mismanagement.

That Lake Mead’s worth of water that has disappeared from beneath the lower Colorado basin has gone largely to irrigating alfalfa and other food for cows, much of which is exported. The Southwest is also the site of many planned data centers, an industry that might guzzle 74 billion gallons of water per year in the U.S. by 2028, according to a December study by the Lawrence Berkeley National Laboratory. About two-thirds of all the data centers built or planned in the U.S. since 2022 are in areas of high water stress, according to the nonprofit World Resources Institute.

This isn’t just a U.S. problem: Groundwater depletion is rampant in North Africa, the Middle East, the Tibetan Plateau and northern China, the study points out. One possible reason groundwater loss doesn’t dominate headlines the way climate change does is that too many people see it as a regional issue. Given that it now affects most of the Earth’s population and is making all the seas rise, it’s clearly a global issue.

And it’s a disaster with compounding effects. Lack of water affects agriculture, as in much of southern Africa, where a drought parched crops and livestock and put 90 million people in danger of acute hunger, according to a United Nations report last month. It affects commerce, as in the Panama Canal, where in late 2023 the water fell to levels too low to accommodate big ships. Droughts in Thailand and India boosted global sugar prices, while parched Spanish olive groves led to two years of soaring olive-oil prices. Loss of water and food sparks mass migration and violent conflicts.

Water shortages also lead to energy shortages. Hydroelectric power generates nearly a third of electricity on the U.S. West Coast, a figure in slow decline over much of the past decade. Failing hydro power in Zambia last year led to 21-hour blackouts.

The good news is that this crisis has solutions. We could start by curbing the fossil-fuel use heating up the planet. We could also eat less of that thirsty beef. Sure, those are probably the hardest things, but everything we do will take political will and foresight. We can grow drought-resistant crops and make data centers and other industries less water-intensive. We can rebuild water-collecting wetlands and improve our ability to capture the rain that will keep falling in those torrential downpours.

The first step, and maybe the easiest but most critical of all, is to stop thinking of fresh water as an infinitely replaceable resource.

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With assistance from Liam Denning.

This column reflects the personal views of the author and does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Mark Gongloff is a Bloomberg Opinion editor and columnist covering climate change. He previously worked for Fortune.com, the Huffington Post and the Wall Street Journal.

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