FAUSTA ORTIZ, 38, Pastoruri’s glacier guardian, stands on top of rocks that years ago where covered with ice, in Huaraz, Peru. According to Alejo Cochachin, co-ordinator of the glaciology unit, the Pastoruri glacier retreated 576 meters between 1980 and 2014. Peru’s glaciers have lost more one-fifth of their mass in just three decades.