Australia's tropical marine ecosystems are already responding to regional consequences of global climate change caused by enhanced greenhouse gas emissions.
Even with national and international commitment to stringent mitigation strategies that stabilise and reverse atmospheric greenhouse gas concentrations by the middle of this century and (hopefully) keep average global warming below ~2-2.5oC by 2100, tropical marine climates are experiencing and will continue to experience rapid and significant changes causing organism and ecosystem responses.
It is not simply a change to a new climate regime to which the ecosystems have to adapt. For the foreseeable future, climate will be continuously changing and it may be tens to hundreds of years before a new, stable climate regime is reached, assuming international success at greenhouse gas mitigation.
Changes to the physical environment include:
- continued warming of ocean temperatures (with mass coral bleaching responses already observed);
- gradual acidification of the ocean (likely to reduce the ability of various marine calcifying organisms to form their skeletons and shells);
- tropical cyclones of increased intensity (causing local physical destruction);
- more extreme rainfall events (with increased amounts of freshwater extending further away from the coast);
- gradual sea-level rise (affecting coastal erosion, storm surges and the area available for shallow-water marine organisms); and
- changes in ocean circulation and upwelling patterns (presently ill-defined but fundamental to many ecological processes).
Against this backdrop of rapid environmental change, informed management strategies need to identify the magnitude and spatial and temporal dimensions of physical and biological changes and responses.
The climate change team will provide this information through:
- placing current changes and responses in an historical context;
- mapping the evolving spatial risks and resilience using both physical and biological data;
- downscaling large-scale climate scenarios to space scales relevant to coral reef processes and providing a theoretical framework (model) for assessing the impacts of various future changes and management actions; and
- assessing the ecological responses of coral reefs and monitoring trends in the physical environment through up to date ocean observing systems.
Group leader: Dr Ken Anthony