AIMS undertakes interdisciplinary research to provide managers and policymakers with the best available understanding of the vulnerability of coral reef ecosystems to climate change, ocean acidification and local environmental stressors. This knowledge helps guide management of ecosystem resilience.
Rapid, human-induced climate change is one of the greatest threats to the long-term future of coral reefs. Human activities are taking coral reefs out of their comfort zone where they have thrived for hundreds of thousands of years.
In combination with other natural and human-induced pressures, warming sea surface temperatures and ocean acidification increase the vulnerability of coral reefs to coral bleaching, coral diseases, crown-of-thorns starfish and tropical cyclones.
Impact on marine ecosystems
Australia’s tropical marine ecosystems, like the Great Barrier Reef, are already experiencing the consequences of climate change. AIMS research reveals that tropical sea surface temperatures have risen by 0.4–0.5 °C since the late 19th century.
Since the late 18th century, the oceans have also absorbed about 30 per cent of the extra carbon dioxide that human activities have injected into the atmosphere. The additional carbon dioxide in the oceans has changed their chemistry—in a process known as ocean acidification—with the pH of the global oceans decreasing from around 8.15 to around 8.05.
AIMS’s modelling and experimental studies show that increased acidity impairs the ability of corals and other calcifying organisms to build their calcium carbonate skeletons, which are the backbone of tropical coral reef ecosystems.
The resulting complex reef structures provide food and habitat for many thousands of reef-associated organisms, resulting in the incredible biodiversity of tropical coral reefs.
Climate change is predicted to affect tropical marine systems in the following ways:
- Warmer sea surface temperatures will increase the risk of heat stress events and mass coral bleaching.
- Tropical cyclones are likely to be more intense, resulting in physical destruction and weakening of the reef structure.
- Extreme rainfall events will increase, with larger amounts of low-salinity freshwater and sediment extending further out from the coast.
- Sea levels will gradually rise, affecting coastal erosion, the magnitude of storm surges and the area available for shallow water marine organisms.
- Ocean circulation and upwelling patterns will change.
AIMS contributes to understanding the implications of climate change by:
- monitoring, reconstructing and modelling the changing ocean climate
- assessing the combined impact of cumulative climate change with stressors such as poor water quality on coral reefs and tropical marine organisms
- identifying the attributes of ‘healthy’ coral organisms that make them more resilient to rapid environmental change
- identifying adaptation and acclimatisation mechanisms and locations that may provide refuges for marine species in a rapidly changing world.
Our National Sea Simulator (SeaSim) also plays a key research role by replicating future climate scenarios and supporting large, long-term, multi-factorial experiments. This research is helping our scientists to better understand the impact of complex environmental changes.