Tourist stand in front of Peak Bolivar at the Sierra Nevada in the Andean state of Merida July 30, 2008. Global warming is quickly melting glaciers in South America's Andes mountains, threatening to cut available drinking water for millions of residents and cripple hydro-electricity generation projects. The melting of the Andean glaciers from Chile to Venezuela threatens the largest supply of fresh water outside the North and South poles, with the snow-cap of Venezuela's 4979 meter Bolivar Peak possibly disappearing in five years. Picture taken July 30, 2008. REUTERS/Jorge Silva (VENEZUELA)