Australia and Japan have joined forces to assess the impact of climate change on the Antarctic marine system.
The collaboration was established in 2009 in response to a joint Prime Ministers’ statement on the importance of enhanced collaboration between the two countries in Antarctic climate science.
The resulting project, ‘Establishing a benchmark to assess climate change impact in the eastern Antarctic marine system’, is coordinated through the Antarctic Climate and Ecosystems Cooperative Research Centre and Japan’s National Institute of Polar Research.
‘Australia and Japan both operate permanent research stations in the Indian Sector of the Southern Ocean and have collected vast amounts of pelagic (open ocean) data over the past 30 years during marine science cruises covering more than a quarter of the Antarctic coastline,’ says Australian Antarctic Division krill biologist Dr So Kawaguchi, who leads a component of the project.
‘The aim of this project is to bring together all this data into a single database so that we can systematically analyse it for changes over the past few decades.
‘This will allow us to identify the gaps and limitations in the data, which is important when it comes to interpreting trends in the data or deciding whether we need to collect new data. It will also allow us to identify key geographic areas that are likely to provide answers to the important climate change questions, so that we can plan future observation and monitoring work in these areas.’
Among the questions being investigated are: what is the current state of biology in the Southern Ocean and how does it respond to physical changes; what will happen to Antarctic ecosystems if the polar front (Antarctic Convergence) contracts further south as the Southern Ocean warms and freshens; and are observed changes in biological ecosystems the result of a one-off event (such as the Mertz Glacier calving), part of a decadal cycle or part of a long-term trend?
Two types of data are being combined in the project: ‘ecosystems’, or biological data relating to such things as krill, phytoplankton and zooplankton; and ‘physical oceanography’. The oceanographic data provides a context for the biological data, as changes in ocean properties such as temperature, acidity and sea ice cover, will affect the organisms living in it.
Since the project’s inception a number of different groups have expressed interest in contributing new datasets to the original pelagic datasets, including ice core records and Adélie penguin population data. These additions will improve the ability to see climate change links between different components of the Antarctic ecosystem.
The combined data will also be used to understand the habitat requirements of organisms within the system and to model changes in the system over time.
At workshops in Tokyo and Hobart, just prior to the conclusion of the two-year project in March 2011, the team analysed some of the data to look for trends. Significant changes were observed in parts of the sector relating to the timing of annual sea ice advance and retreat and the duration of the annual sea ice season, and further analysis is underway. One long-term study also identified changes in the composition distribution and diversity of plankton and krill (see Southern Ocean plankton is changing). But no significant trends were detectable elsewhere.
‘Collectively something is happening in many components of the ecosystem, but individually the trends aren’t strong,’ Dr Kawaguchi said.
‘However, there is published data and other information available which may strengthen some observations and help identify the drivers of the trends we did see.’
Further analysis will be undertaken this year and a series of trends papers is planned for a special edition of the PLoS ONE journal. The work is expected to feed into the Fifth Assessment Report of the Intergovernmental Panel on Climate Change in 2014.
While the initial two-year project has just ended, Dr Kawaguchi said a long-term collaboration has begun. This collaboration will include the coordinated collection of new data at strategic sites in the Indian sector of the Southern Ocean, development of a biological and physical observation system, the standardisation of existing data in the database and its release to all researchers, and development of a spatial habitat model.
In the future the team hope to expand the spatial coverage of their database through collaborations with other countries operating in the East Antarctic sector, such as France, South Africa, New Zealand, Italy, the United States and Germany.
WENDY PYPER
Corporate Communications, Australian Antarctic Division