East African coral reefs at risk as temperatures rise

Global warming is taking a toll on coral reefs off east Africa, which will likely be killed off in a few decades if sea surface temperatures continue to rise, a leading researcher warned on Tuesday.

"Dangerous climate change has already happened for coral reefs," Dr David Obura told a conference on climate change science in Johannesburg.

Kenyan Obura, a researcher with Coral Reef Degradation in the Indian Ocean, said there had been "catastrophic mortality" among shallow-water coral reefs off East Africa following a 1997-98 El Nino event that pushed up sea surface temperatures in the Indian Ocean.

"There was a 70 to 75 percent mortality during the El Nino in 1997-98 in shallow water reefs off East Africa," he said.

Models suggested that the events of 1998 could be repeated on a regular basis in 20 to 50 years' time because of rising sea surface temperatures.

Such a scenario would have grim consequences for the region's rich corals, which are crucial to East Africa's tourist industry, as they are a magnet for scuba diving enthusiasts.

"They (corals) can survive a bleaching. It is akin to a fever in mammals," Obura said. But if the stress was too great on the corals, then they died off.

Coral bleaching refers to the whitening of corals from a loss of pigment.

This is a signal of ecosystem stress which can be triggered by sedimentation, pollution, or rising temperatures, among other factors still being disentangled by scientists.

Scientists maintain global temperatures are rising rapidly because fossil fuel emissions from cars, industry and other sources are trapping the Earth's heat.

The Intergovernmental Panel on Climate Change, a group of 2 000 scientists which advises the United Nations, projects a further rise of between 1,4 and 5,8 degrees centigrade by 2100.

Even the lowest forecast would be the biggest century-long rise in 10 000 years.

Source: www.iol.co.za