By Richard Black
BBC environment correspondent
A delegation of environmental lawyers is starting a new initiative to force action on global warming.
Campaigners demand urgent assessment of the risks to Everest
They are arguing that governments which are members of Unesco - the UN's cultural and scientific agency - are legally bound to protect World Heritage Sites from damage.
Some sites are threatened by climate change, they say - and governments can only protect them by reducing emissions of greenhouse gases.
Legal dossiers concerning three World Heritage Sites will be delivered to Unesco in Paris this week.
"There's a very important mechanism in the World Heritage Convention," said Peter Roderick, director of Climate Justice, the organisation co-ordinating this action.
"It entitles people to ask the World Heritage Committee to place the site in danger on this list, and thereby ensure it gets more protection," he told BBC News.
"And so we're saying to the World Heritage Committee, 'look, climate change is already affecting these priceless and irreplaceable parts of the planet'."
This campaign involves three "priceless and irreplaceable" places: the Belize Barrier Reef, where, conservationists say, coral is dying as water warms; Huascarán National Park in Peru, and Sagarmatha National Park in the Himalayas.
In these two mountain ranges, the dossiers say, ice is melting away; even the world's highest mountain, Everest, could one day be nothing but rock.
Mark New, a climatologist from Oxford University, UK, who works on the Himalayas, told BBC News: "We know that over the last 30 years, in the eastern Himalayas, snow cover and ice cover have decreased on average by about 30%; so there's 30% less ice and snow than there was 30 years ago."
Healthy great star coral (top) and diseased (bottom)
Relatively little science has been done on the highest mountains, because they're so hostile and inaccessible.
But a documentary to be released this week, made by the independent British film-maker Richard Heap, with support from the United Nations Environment Programme (Unep), shows anecdotal evidence that the Himalayas are changing.
At an altitude of over 4,000m, the crew found a vast glacier lake, which according to their maps, had not been there a few decades before. There had, though, been a glacier.
They also found large tracts of ice which were, in mountaineers' terms, "rotten" - wetter, and less stable than they had been on previous expeditions decades earlier.
The Nepalese environmental group Pro Public is leading the Himalayas campaign to Unesco, and it is concerned about more than natural beauty.
Glacier lakes can overflow, sending sudden massive torrents of water down populated river beds.
In the long term, there are also concerns for south Asia's water users.
Himalayan ice melts into the waters of major rivers such as the Ganges, the Indus, and the Brahmaputra; as the ice disappears, so may substantial portions of south Asia's water supply.
"We are the least developed countries and we don't have many resources," said Prakash Sharma, executive director of Pro Public.
"And also, the Nepalese are not responsible for what's happening there - maybe we might be a little bit responsible, but I think [it is] the global phenomenon of climate change.
"The parties to this convention have agreed to protect the World Heritage Site because it is the unique part of the world, and we need to protect it."
After Unesco receives its three dossiers, it can if it wishes set up inquiries into what is happening in Sagarmatha, Huascaran and the Belize reef.
It can then demand action from member states, including limits on carbon dioxide.
The organisation would, though, first have to prove that what is happening is undeniably down to global climate change - which, in the Himalayas at least, might be difficult.
"At the moment it's not possible," said Mark New.
"The Himalayas are a climatologically very complex area - there's a lot of variability in the climate system that tends to obscure what might be a climate change signal."
Even if Unesco did command the big emitters to make big cuts, there is nothing in the World Heritage Convention which could force them to comply - rather like Kyoto itself, the convention is long on good intentions, but lacks a big punitive stick.
Even so, a strong judgement would have important symbolic value.
"It's very important that Unesco says that the legal obligation of parties to the World Heritage Convention will not be complied with unless greenhouse gas emissions are cut," said Peter Roderick.
"Because you have an obligation to pass these sites on to future generations; and if we cannot do it for the best parts of the planet, then - what kind of species are we?"