PATAWASI, THE ANDES, PERU - JUNE 21: A glacial valley formed over thousands of years high in the Andean mountains, Patawasi, Peru, 21 June 2007. Glaciers in Peru are in severe retreat as a result of global warming. Peruvians are highly dependant on glacial water supply and the majority of the population lives in an area where this is the majority water source. (Photo by Brent Stirton/Getty Images)
