The climbers leave the trash. I forget how many tons of trash is believed to have been tossed down crevasses, etc. over the years. More recently they have become aware of hauling the garbage back down. (Well - the government, not the climbers so much I don't think.)
IIRC, in the Mouse on the Moon book by Leonard Wibberley, they spaced all their trash en route, so when they arrived, all the trash also splashed down.