Heading to the mountains used to mean getting away from civilization and its discontents — but increasingly, mountains are a showcase for global problems instead. That was the conclusion of a report released yesterday by the United Nations, which found that wars, pollution, and logging are threatening the world’s mountain ranges. Mountains supply water to more than half of the world, and are home to 10 percent of the global population. But they are being despoiled by impoverished communities turning to logging, wealthy communities turning to skiing and other luxury recreational activities, pollution, and violent conflict. (Twenty-three of the world’s 27 current conflicts are being fought in mountainous areas.) Among the most threatened ranges, according to the report: the Alps, the Rockies, and Afghanistan’s Hindu Kush.