Science says Sydney Harbour has a growing carbon pollution problem

Mark Metcalfe/Getty Images

Australian scientists have for the first time defined the carbon footprint of Sydney Harbour.

The global landmark may look pristine but a study published today shows it is a source of significant carbon emissions, which require careful management as the city double its population to 10 million by the end of the century.

The CO2 emissions from the Harbour are 1000 tonnes a year, equivalent to the pollution from 200 cars.

“The 1000 tonnes of CO2 we found are emitted from Sydney Harbour each year is significant but it’s a small amount for an estuary of that size,” says Lead author and PhD candidate Edwina Tanner in the University of Sydney’s School of Geosciences.

The research, by the Marine Studies Institute at the University of Sydney and the Centre for Coastal Biogeochemistry at Southern Cross University, is the first long term study of such a large Southern Hemisphere system referred to as a drowned river valley, which in Sydney spans estuaries from Middle Harbour to Lane Cove and Parramatta.

The emissions from Sydney Harbour, including from urban runoff, leaf litter, soil decomposition and sewage overflow, were found to be low compared to the highly polluted estuaries of Europe and Asia, which can emit up to 76,500 car CO2 equivalents each year.

CO2 emissions from the upper estuaries decreasing towards the well flushed lower estuary. Image: Estuarine, Coastal and Shelf Science.

Sydney’s emissions measure at a similar, bit slightly lower level, to other natural drowned river valleys in the US such as the Hudson River, which flows through New York.

Tanner says monitoring of estuarine CO2 is important for planning.

“As each estuary is different, the potential impacts of climate change and urban development will be different in every ecosystem,” she says.

Professor Bradley Eyre from Southern Cross University, co-author and supervisor, says the research should play an important role in quantifying the significant carbon footprint of estuaries in built-up areas worldwide.

The research is published in the international journal Estuarine, Coastal and Shelf Science.

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