The Penuelas reservoir in central Chile was until 20 years ago the main source of water for the city of Valparaiso, holding enough water for 38,000 Olympic-size swimming pools. Water for only two pools now remains. In a historic 13-year drought, rainfall levels have slumped. It is totally unrivalled for duration or intensity.
The drought has hit mine output in the world’s largest copper producer, stoked tensions over water use for lithium extraction and farming, and led the capital, Santiago, to make unprecedented plans for potential water rationing.
Behind the issue is a global shift in climate patterns sharpening natural weather cycles. Normally, low-pressure storms from the Pacific unload precipitation over Chile in winter, recharging aquifers and packing the Andes mountains with snow.
But naturally occurring warming of the sea off Chile’s coast, which blocks storms from arriving, has been intensified by rising global sea temperature, according to a global study on sea temperature and rainfall deficits. Ozone depletion and greenhouse gases in the Antarctic, meanwhile, exacerbate weather patterns that draw storms away from Chile, according to a study on variables affecting Antarctic weather.
It meant the Andes were not getting a chance to replenish, which in turn meant that as snow melted in spring there was far less water to fill rivers, reservoirs and aquifers.
As snow compacts, it creates new layers, which help keep it colder for longer. But with warmer weather and less snowfall, Miguel Lagos, a civil engineer and water specialist, said, top layers of snow were melting faster or turning straight to vapour, a process called sublimation.
researchers at the University of Chile predict the country will have 30% less water over the next 30 years, based on mathematical models and historic data.
“What we call a drought today will become normal,” Lagos said.