Coral fears

Abstract

The rich coral reefs of south-east Asia are under increasing threat from human activity and climate change. Nigel Williams reports. The rich coral reefs of south-east Asia are under increasing threat from human activity and climate change. Nigel Williams reports. There is a growing threat to the so-called coral triangle in south-east Asia — home to 3,000 fish species and 40 per cent of the planet's most significant marine environment. Pollution and deforestation have already caused significant damage and these and other threats may destroy all the coral reefs by the end of the century according to Ove Hoegh-Guldberg, director of the Centre of Marine Studies at the University of Queensland and lead author in a new Worldwide Fund for Nature (WWF) report∗. The coral triangle covers an area the size of the US and is home to more than 35 per cent of coral reef fish and 30 per cent of the world's corals. “More marine species exist in the coral triangle than are found in all the other tropical oceans put together,” the report says.“This report delivers a sombre warning that action must be taken immediately. There are a number of actions discussed which, if implemented by regional and world leaders, will avoid this crisis.” “This report delivers a sombre warning that action must be taken immediately. There are a number of actions discussed which, if implemented by regional and world leaders, will avoid this crisis.” The coral triangle spans Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands and Timor-Leste and comprises 18,500 islands rich in mountain forests and woodlands. The escalation of modern practices, such as deforestation, coastal reclamation, destructive fishing and the pumping of pollution and sewage into the sea, over the past 40 years has already destroyed about 40 per cent of coral reefs and mangroves. If such practices are unchecked, half the species in the coral triangle will continue to disappear at a rate of 1–2 per cent a year, the report says. “This may sound alarming but this is not alarmist. This is probably what we are going to experience if we don't get our act together,” says Hoegh-Guldberg. Based on a review of more than 300 peer-reviewed scientific studies in biology, economics and fisheries, the report also predicts problems ahead for the six nations within the coral triangle. The reefs, which support industries such as fishing and tourism, are also nursery areas for many species of fish. The report considers two scenarios. The worst case would be if the global agreement to cut carbon emissions, to be signed in Copenhagen in December, fails significantly and carbon emissions continue apace. This would, the report says, result in the region suffering increasingly severe drought, typhoons and political unrest. Food supplies would shrink and freshwater supplies would be swamped by rising sea levels. But even bleaker is the stark warning in the report that “the pathway that the world is on today exceeds the worst-case scenario described in the report.” “Rapid changes in the Earth's climate are now beginning to affect the terrestrial and marine ecosystems of the coral triangle. Changing weather patterns are increasing the risk of floods, landslides and severe storms… while causing crippling drought in other areas,” the report says. “Examination of the trends of how the climate is changing reveals that sea temperatures in large parts of the coral triangle are increasing at around 0.4°C per decade, while other parts are increasing at lower rates (0.1°C per decade). Disturbances to the hydrological cycle in the region will almost certainly lead to changes in rainfall across the region, with rainfall intensity increasing in some regions and dramatically decreasing in others, thereby causing drought, computer models suggest. This may bring about large-scale changes in sediments and river effluent flowing into coastal areas. Rises in sea level represent a serious threat with scientists at the recent climate science meetings in Copenhagen, ahead of the main December meeting, suggesting that sea-level changes may have been severely underestimated by the International Panel on Climate Change's fourth assessment report and that seas may rise by at least one metre by the end of the century. “At the upper end of these scenarios, sea-level rise could have devastating impacts on coastal ecosystems such as coral reefs, mangroves and seagrass beds, as well as inundating coastal communities.” “Coral reefs appear to be particularly sensitive to increases in sea temperature. Corals… bleach and die if temperatures increase by a couple of degrees above long-term averages.” “Rising sea levels are putting pressure on coastal communities,” the report says. In the second scenario, based on the Intergovernmental Panel on Climate Change, “the international community takes decisive and effective action which rapidly reduces greenhouse gas emissions, and resolves to assist countries like the coral triangle nations to develop effective solutions to the growing problems they face.” If such measures are taken there is the possibility to “limit the impacts of the changing climate and maximise the resilience of biological, ecological and socioeconomic systems,” the report says. “This report delivers a sombre warning that action must be taken immediately. There are a number of actions discussed which, if implemented by regional and world leaders, will avoid this crisis.”