For years, Nepal’s government has faced pressure to reduce rubbish in the Himalayas, where decades of commercial mountaineering have left large amounts of discarded gear, human waste and other debris on some of the world’s tallest peaks. Last week, the authorities in Kathmandu finally took firm action. They approved a landmark five-year plan to clean up Nepal’s mountains, seeking to curb waste through stricter monitoring and limiting the number of climbers on Mount Everest, the world’s highest...