The water from the melted snow then collected in a 25-square-mile slushy lake, known as a "snow swamp," on the glacier. Just two weeks later, this pool of water then evaporated completely.

To see if reality matched with the theory, in the summer of 2017 Keller and Oerlemans ran a pilot scheme in which they sprayed, in two rounds, a 2.5-metre-deep coat of artificial snow onto a 200 ...

Parts of the snow take on bright colors: deep red, rusty orange, lemonade pink. Locals call this “sang de glacier,” or “glacier blood.” Visitors sometimes go with “watermelon snow.” ...