KATMANDU, Nepal » Fresh snow and unpredictable weather hampered efforts to pick tons of trash left behind by climbers on the slopes of Mount Everest, the veteran mountain guide who led the cleaning crew said Friday.

"The new snow covered the garbage and it was difficult to collect trash in the higher altitude," the guide, Apa, told reporters upon his return to the Nepalese capital of Katmandu. Apa, like most Sherpas, use only one name.

Before leaving for the mountain in April, Apa said his team planned to clear 8,800 pounds (4,000 kilograms) of garbage from the lower part of the mountain and another 2,200 pounds (1,000 kilograms) from near the summit.

Apa said they only managed to bring down 2,400 pounds (1,100 kilograms) of garbage in total.

The guide, however, did manage to reach the 29,035-foot (8,850-meter) summit with a group of other climbers on May 11. That was his 21st successful ascent of the peak, breaking his own record for most climbs set last year.

Apa, 50, grew up in the foothills of Everest and began carrying equipment and supplies for trekkers and mountaineers at age 12. He first climbed Everest in 1989 and has repeated the feat almost annually.

Apa has long campaigned about the degradation he has seen on the Himalayan peaks due to global warming and other issues.

He said when he first began climbing Everest, the trail to the summit was covered with ice and snow. Now, it is dotted with bare rocks. The melting ice has also exposed deep crevasses, making expeditions more dangerous.

Apa moved to the United States in 2006 and lives in the Salt Lake City suburb of Draper.