South America is experiencing one of the most extreme weather events on record, with temperatures in parts of Chile and Argentina topping 100 degrees Fahrenheit in the dead of winter. Raúl Cordero, a climatologist from the University of Santiago, says the unprecedented winter heat could threaten water supplies to major cities in the months ahead.

Raúl Cordero Carrasco: “One of the problems of high temperatures during winter is that they quickly melt seasonal snow. In countries like Chile, the provision of water during the dry season, spring and summer, relies on the natural storage that’s in the mountain snowpack. It’s a natural reservoir that provides water to communities and big cities in central Chile.”

A new report by Climate Central finds global heating made the month of July hotter for more than 80% of humanity — more than 6.5 billion people.