The United Nations is facing pressure from scientists and campaigners to acknowledge the potentially devastating effect of climate change on the world's most precious ecological sites.
Environmental activists, who are concerned that poorer countries with low greenhouse gas emissions are being saddled with the damage wreaked by richer countries' soaring emission levels, are pressing the UN World Heritage Sites Committee to admit that five of its most important sites are being damaged, perhaps irrevocably, by climate change. The barrier reefs of Belize and Australia and glacier parks in Nepal, Peru and the Rockies are supposed to be among the best-protected areas in the world, but are already showing clear signs of the effects of global warming.
The World Heritage Sites Committee, which stipulates that listed sites should not be damaged by its signatories, is preparing to hear a petition brought by scientists, which, if successful could lead to poor countries attempting to sue richer neighbours for emitting greenhouse gases.
Scientists in Belize working on the barrier reef there believe their case is particularly strong. They say the reef, which runs for almost 200 miles along the coast of central America, has suffered more than 40 per cent damage due to bleaching since 1998, and that much of it is now so badly fractured that another hurricane this season would simply sweep it away.
Coral bleaching brought on by high temperatures in the western Caribbean has left the whitened reef vulnerable to over-fishing, pollution, hungry sea creatures and snorklers, as well as the storm waves that accompany hurricanes. Local fishermen say there was no evidence of bleaching before 1998. Billy Leslie of the Hustler Dive School in San Pedro in northern Belize said: "My father was a commercial fisherman. He tells me that we have never heard of coral bleaching like this. It's a horrible sight to see the coral just gets whiter and whiter every day."
Richard Foster, a wildlife cameraman, says: "I first started diving here in the early Eighties and you just won't believe the difference of today. The corals were so thick they were competing with each other on the bottom. There was no space between the corals. Now you've got these open spaces with grey dying coral and the occasional live one in between. It's very sad to see."
Dr Melanie McField, from the Smithsonian Institution in Washington, has been studying the reefs for15 years and is confident that climate change is a key factor. "On an annual basis the sea temperatures in the Caribbean haven't changed much," she said, "but we are now registering prolonged periods of severe heating that we didn't see before. When the water temperature is elevated we get a bleaching alert. The other big sign that the water temperatures are to blame rather than local pollution is that the bleaching episodes happen all over the Caribbean at the same time."
Dr McField expressed anger that Belize has been working hard to protect its reefs but is suffering from a problem beyond its control. This, she said, is an example of a small country with low greenhouse gas emissions bearing the brunt of damage they did not cause.
She is also concerned about another major threat to the future of the corals - ocean acidification. The Royal Society argued last year that so much CO2 from fossil-fuel burning was being absorbed into the oceans that surface waters were becoming dangerously acidic. Research shows that many species of coral are easily damaged by even a slight lowering of pH levels.
A small minority of coral researchers believes that fears over climate change and acidification have been exaggerated. They argue that over time the reefs will adapt to warmer waters and that calcium littering the ocean floors will buffer the effects of acidification.
Dr McField said she accepted that reefs might eventually adapt but that this could take thousands of years. In the meantime, she warned, poor countries making money from the reefs would suffer huge economic damage. In Belize the reef is a major tourist business - nearly half of the country's 260,000 visitors come to see it - and also the mainstay of the economically vital fishing industry.
Miguel Alamilla, who runs a marine protected area off the town of San Pedro, said the short-sighted environment policies of bigger industrial countries was harming those in the developing world. "They need to open up and not be egotistical. They need to think globally," he said. "Be aware that people are dependent on the coral reef and their livelihoods depend on that. If it is destroyed what will happen to them?"
The UN campaigners believe these are powerful arguments in their favour. But they will face determined resistance from the US when the committee meets between 8 and 16 July. Washington argues that there is no conclusive proof that the Belize coral reef is being damaged by greenhouse gases, and that any damage to the reef is accidental and therefore not in breach of the World Heritage Sites treaty.
Roger Harrabin, who is the BBC's environment analyst, reports from Belize on BBC TV News this evening.
Environments under threat
Belize Barrier Reef
Described by Charles Darwin as the "most remarkable reef in the West Indies", half of Belize's annual 260,000 tourists visit the World Heritage Site. It is a victim of severe coral bleaching.
Great Barrier Reef
Australia's most famous reef is home to one of the most intensely populated ecosystems. It isprotected by World Heritage status but is highly sensitive to climate change.
Sagamartha National Park
Surrounded by mountains, Nepal's Sagamartha (literally, Mother of the Universe) is home to the glaciers that feed into the Ganges river system. As climate change melts its glaciers, the park and the millions in India and Bangladesh who rely on Himalayan rivers are at risk.
Husascaran National Park
The Cordillera Blanca mountain range and Peru's Husascaran National Park make up the world's highest tropical mountain range and are a vital asset to Peru both financially and scientifically. The park's plunging ravines are fed by a host of glacial lakes, which are highly susceptible to the effects of climate change.
The national park, which straddles the US and Canada and was the first region in the world to be declared an International Peace Park, has already lost 80 per cent of its glaciers because of rising summer temperatures.Reuse content