Impacts of climate change
The Great Barrier Reef is internationally renowned for its biodiversity. Its network of reefs — about 2900 in total — is home to thousands of species. Extensive areas of seagrass meadows, mangrove stands, saltmarsh and sand and mud areas also provide a diverse range of habitats for many species. The diversity of the Great Barrier Reef’s natural values makes it a particularly unique and valued ecosystem.
Understanding the vulnerability of such a large and intricate system to climate change is a challenge.
We must first understand how climate change will affect an individual species or a community of different species. Identifying how these predictions will influence the entire Great Barrier Reef is a much larger challenge. However we do know, while few systems are likely to benefit from climate change, coral reefs are particularly vulnerable.
The vulnerability of corals to future climate change has received considerable attention, as impacts on them have already been observed. Coral bleaching has begun to increase in frequency and severity due to rising sea temperatures. These events have led some experts to claim that coral reefs around the world are ‘in crisis’. Mass coral bleaching has occurred worldwide, devastating reefs in some regions including the Maldives, Seychelles and Palau. The Great Barrier Reef has not suffered extensive damage due to coral bleaching. However, approximately five per cent of reefs in the Great Barrier Reef were severely damaged in each of the 1998 and 2002 mass coral bleaching events. Projections of future water temperatures suggest coral bleaching could become an annual event in the course of this century.
Many other species, including microbes, fish, marine turtles and seabirds, are also temperature sensitive. Scientists predict impacts on these species under future climate change projections. For example, the gender of turtle hatchlings is temperature determined; higher temperatures lead to an increased proportion of females.
However, increased temperature is just one of many effects of climate change on the Reef. The other environmental changes predicted, suggest there will be additional impacts. Some may have severe consequences. The implications of ocean acidification for animals and plants that produce calcium carbonate skeletons, for example, could be profound. While rising sea level could lead to large redistributions of benthic (bottom-dwelling) habitats and the animals that depend on them.
As our awareness of climate change has increased, so, too, has our need to understand the threat it poses. Knowledge of the vulnerability of the Great Barrier Reef to climate change is essential to meaningfully respond to this challenge. Leading experts are currently working with the Great Barrier Reef Marine Park Authority (GBRMPA), to fully assess the vulnerability of the Great Barrier Reef to climate change. This vulnerability assessment will be completed in 2007.
Climate change cannot be fully averted and we must understand, prepare and adapt to the inevitable effects of climate change. GBRMPA’s Climate Change Response Programme is taking important steps towards reducing the negative impacts of climate change on the Great Barrier Reef.