Himalayan lakes are swelling from the runoff of melting glaciers, environmental campaigners warned as the 29th session of the UN Environmental, Scientific and Cultural Organisation's (Unesco) World Heritage Committee got under way on Sunday in Durban.
Many of the lakes could burst, threatening the lives of thousands of people and destroying Everest's unique environment, they said.
"The warming of the environment of the Himalayas has increased noticeably over the last 50 years. This has caused several and severe floods from glacial lakes and much disruption to the environment and local people," Hillary said in a statement released on Monday.
"Draining the lakes before they get to a dangerous condition is the only way to stop disasters."
The New Zealander, who with Sherpa Tenzing Norgay first scaled the world's highest peak on 29 May 1953, is one of a collection of climbers and others who have joined the environmental lobbying groups Friends of the Earth and Climate Justice Programme in calling for the inclusion of Nepal's Everest National Park on Unesco's World Heritage in Danger List.
"The warming of the environment of the Himalayas has increased noticeably over the last 50 years. This has caused several and severe floods from glacial lakes and much disruption to the environment and local people"
Sir Edmund Hillary
Inclusion would commit the UN body to assessing the risk to the park and developing corrective measures in conjunction with the government of Nepal.
The World Heritage Committee is responsible for implementing the 1972 UN Convention on the protection of cultural and natural sites around the world.
Forty-two new sites will be proposed for inclusion on the body's World Heritage List at the weeklong meeting in Durban.
The list already protects 788 sites, of which 35 are designated as endangered.
"Mount Everest is a powerful symbol of the natural world, not just in Nepal," said Prakash Sharma, Director of Pro Public, Friends of the Earth Nepal. "If we fail to act, we are failing future generations and denying them the chance to enjoy the beauty of mother earth."