Climate change rapidly warms and acidifies Australian estuaries

Elliot Scanes, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia; School of Life and Environmental Science, University of Sydney, Darlington, Australia, Peter Scanes, NSW Office of Environment and Heritage, Sydney, NSW, Australia and Pauline Ross, School of Life and Environmental Science, The University of Sydney, Camperdown, NSW, Australia

Background/Question/Methods
Climate change is impacting ecosystems worldwide. Estuaries are diverse and important aquatic ecosystems; and yet until now we have lacked information on the response of estuaries to climate change. Here we present data from a twelve-year monitoring program, involving 6200 observations of 166 estuaries along >1100 kilometres of the Australian coastline encompassing all estuary morphologies.
Results/Conclusions
Estuary temperatures increased by 2.16oC on average over 12 years, at a rate of 0.2°C year-1, with waters acidifying at a rate of 0.09 pH units and freshening at 0.086 PSU year-1. The response of estuaries to climate change is dependent on their morphology. Lagoons and rivers are warming and acidifying at the fastest rate because of shallow average depths and limited oceanic exchange. The changes measured are an order of magnitude faster than predicted by global ocean and atmospheric models, indicating that existing global models may not be useful to predict change in estuaries.