Runoff from land can damage reefs

The UN Foundation was set up to handle the $1bn given to support the UN by the US media magnate Ted Turner in 1997.

The director of Unep's coral reef unit, Arthur Dahl, said: "In many ways coral reefs are very resilient. But they are now proving to be very sensitive to certain kinds of human impacts."

Among the greatest threats, he said, were the use of dynamite by fishermen; overfishing; and thoughtless boat owners who dropped anchor on the reefs and damaged them.

Over the limit

Fertiliser, sewage and soil run-off from the shore is another problem, as is the plundering of the coral for curios and souvenirs.

And climate change is playing a part as well, with rising sea temperatures worsening the plight of the reefs. During the El Nino climate disruption three years ago, up to 70% of Kenya's corals were bleached and damaged.

White areas show coral bleaching

El Nino is a seasonal phenomenon in the Pacific, with repercussions spreading far and wide. It used to happen once every 10 or 15 years, but Unep says it is recurring more often: some researchers claim this is because of global warming.

Arthur Dahl said: "Corals have evolved to grow close to their upper, safe temperature limit.

"The kinds of temperatures seen in 1998 are pushing them beyond that limit. Reducing carbon dioxide (CO2), the key pollutant linked with climate change, would help coral reefs in other ways.

Matching funds

"They produce their skeletons by precipitating limestone from bicarbonate in the water. Increases in CO2 in the water interfere with this reef-building process, making it harder for corals to bounce back."

When reefs are given proper protection, the benefits can be widely diffused. Robert Hepworth, a Unep biodiversity expert, said: "Some of the reefs in East African waters are important not only in their own right but also for mangrove swamps and sea-grass beds.

"These ecosystems are important as natural coastal defences."

The UN Foundation scheme will match however much Unep raises, up to $10m.

It also aims to involve local people in reef protection, and to offer them money and training in new skills, so that they can supplement their incomes if they lose money from measures to save the coral.

Researchers say that more than a quarter of the world's reefs have been damaged by pollution and climate change, and they believe most of the rest could go the same way by 2020.