Human waste, empty oxygen cylinders, kitchen leftovers and discarded ladders.
Sherpas working on Mount Everest carry all that and more — 20 kilograms (44 pounds) per person — navigating a four-hour hike that traverses crumbling glacial ice and treacherous crevasses to bring trash back to base camp.
During the most recent climbing season, they had new assistance from two giant SZ DJI Technology Co. drones, which can complete the same journey in six minutes, sharing the task of clearing an expanding volume of refuse piling up on the world’s highest peak.
The acci…