Our thirst for water is turning the oceans saltier | Artificial intelligence
FOR the time being, Cape Town has dodged a bullet. After months of unrelenting drought, the recent winter rains have begun to refill its parched dams. That doesn’t mean things are easy. City residents are still limited to using 50 litres of water a day, scarcely enough to half-fill a bath. But at least so-called day zero, when the taps run dry and residents have to wait in line to collect survival rations of water, has been averted.
The South African city is an extreme example, but it is far from the only place facing a severe water shortage. To slake that thirst, many cities are turning to the ocean, a seemingly inexhaustible supply of water. They are doing this through desalination, a water purification technology that has been around for decades. Cape Town is bringing a couple of desalination plants online in a hurry and many others are being built elsewhere. As they spring up, however, attention is focusing on what they leave behind: concentrated brine, millions of litres of it a day.
Now scientists are sounding a note of caution about the impacts of dumping all that salt in the environment. “Increasing salinity is one of the most important environmental issues of the 21st century,” says engineer Amy Childress. But smarter methods of desalination are emerging and they have benefits far beyond providing clean water.
Sao Paulo, Cairo, Beijing, Bangalore – the list of cities with water shortages runs long and touches every continent. Even London, often thought of as a wet …