The Great Barrier Reef under threat

Australia’s Great Barrier Reef, a World Heritage site, is vulnerable to stresses such as increases in water temperature and nutrient levels which are likely to be exacerbated by climate change. This Down Under looks more closely at the issues, with particular emphasis on the impact of tropical cyclones and water pollution. It is useful for topics on ecosystems, biodiversity and climate change

The IPCC report on climate change released last year identified several threats to Australia’s Great Barrier Reef. These included more intense tropical cyclone and rainfall events. It also suggested that the combined impact of expected warming and acidification of the ocean will result in increased coral bleaching, disease and mortality, leading to significant change in the composition and structure of the reef. These impacts will be exacerbated by other stresses, including rising sea levels and nutrientenriched runoff.

The reef is already suffering from the impacts of climate change. For example, coral bleaching was identified in 20% of the reefs surveyed by the Great Barrier Reef Marine Park Authority in 2014. Ten per cent of the decline in coral cover since 1985 has been attributed to bleaching. In total, of the 894 reef health and impact surveys carried out across 88 reefs on the Great Barrier in 2013–14, 30% recorded one type of impact and a further 26% recorded more than one impact.