By Richard Black
BBC News environment correspondent
Conqueror of Everest Sir Edmund Hillary has urged world governments to protect the Himalayas from climate change.
Sir Edmund wants Sagarmatha National Park listed as "in danger"
The World Heritage Committee, which supervises protection of sites of special interest, meets this week.
Environmental campaigners, backed by Sir Edmund, want the committee to put the Sagarmatha National Park in the Himalayas on its danger list.
This would mean governments are legally bound to protect it - which, they say, means cutting greenhouse gas emissions.
In May 1953 Sir Edmund Hillary joined forces with Sherpa Tenzing Norgay on the first successful ascent of the world's highest mountain.
Ever since, he has devoted much time to projects which help the peoples of the Himalayas.
Now, a few days short of his 86th birthday, he is turning his attention to climate change.
It is more than 50 years since Hillary and Tenzing made the ascent
"The warming of the environment of the Himalayas has increased noticeably over the last 50 years," he wrote in a statement sent to the BBC.
"This has caused several and severe floods from glacial lakes and much disruption to the environment and local people."
In 1985, the Dig Tsho glacial lake burst its banks, releasing a mountainside deluge which rushed through villages, bringing down 14 bridges.
'Thousands at risk'
Three years ago, a study by the United Nations Environment Programme (Unep) and the International Centre for Integrated Mountain Development (Icimod) found more than 40 glacial lakes were filling so rapidly that a similar outburst was likely.
Tens of thousands of lives were at risk, it concluded, with Unep's Executive Director Klaus Toepfer describing the situation as "another compelling reason to reduce emissions of carbon dioxide and other greenhouse gases".
Petitions before Unesco's World Heritage Committee this week as it meets in Durban, South Africa, are seeking to force action to reduce greenhouse gas emissions.
Mount Everest could make the danger list
Every year the committee can decide whether to award places of special natural, archaeological or cultural interest the status of a World Heritage Site, and whether to add any of those sites to its "danger list".
By ratifying the World Heritage Convention, nations acknowledge that "such heritage constitutes a world heritage for whose protection it is the duty of the international community as a whole to co-operate".
They also undertake to ensure that World Heritage Sites are kept fit for future generations, and "not to take any deliberate measures which might damage directly or indirectly the cultural and natural heritage".
Environmental campaigners are saying that the 180 nations which have ratified the World Heritage Convention have a legal duty to protect Sagarmatha, as well as Huascaran National Park in Peru and the Belize Barrier Reef, from the impacts of climate change.
"Firstly, we will be asking the World Heritage Committee to look carefully at the petitions and urging it to add the sites to the danger list," Peter Roderick - the Director of Climate Justice, the organisation coordinating the petitions - told BBC News.
"This will ensure that they receive the higher level of protection they urgently need, such as assessing and making safe glacial lakes in the Himalayas and the Andes.
"Secondly, we want the committee to review compliance with the parties' duty under the World Heritage Convention to transmit World Heritage Sites to future generations. Plainly, without drastic cuts in greenhouse gas emissions, this legal obligation will not be met."
It is not clear how much support Climate Justice has among governments represented on the World Heritage Committee.
The British government did not respond to a BBC request to make its position known.
But the view of the first man to stand on the roof of the world is unequivocal.
"I support the petition to the Unesco World Heritage Committee... requesting the inclusion of Sagarmatha National Park in the list of World Heritage in Danger as a result of climate change and for protective measures and action."