Police in southwest Switzerland warned Wednesday that a heat wave has increased the risk of falling rock and ice in the Alpine region, where it’s been particularly deadly this year for mountaineers and hikers. Valais regional police say a spike in temperatures and a record high altitude of nearly 5,300 meters (about 17,300 feet) for a bellwether zero-degree Celsius reading over Switzerland has accelerated erosion in the Alps. “With the heat wave of the last few days, and the days to come, the danger level is heightened in the high mountains,” regional police spokesman St...