The research is published in the March 7 issue of the prestigious science journal Nature.

"Our paper shows that carbon storage by coastal wetlands is explicitly linked to sea-level rise," lead author Associate Professor Kerrylee Rogers, from UOW’s School of Earth, Atmospheric and Life Sciences, said.

Researchers from UOW, Macquarie University, Smithsonian Environmental Research Center, USA; Nelson Mandela University, South Africa; Yunnan University, China; and the Australian Nuclear Science and Technology Organisation, analysed carbon stored in more than 300 saltmarshes across six continents, collecting data from the past 6000 years.

"Saltmarshes on coastlines subject to sea-level rise had, on average, two-to-four times more carbon in the top 20cm of sediment, and five-to-nine times more carbon in the lower 50-100cm of sediment, compared to saltmarshes on coastlines where sea level was more stable over the same period," Prof Rogers said.

"Capture and storage of carbon by saltmarshes has a dual benefit. It removes CO 2 from the atmosphere, mitigating greenhouse gas emissions, and the organic carbon that is accumulated builds the elevation of the wetland as sea levels rise."

She added saltmarshes on the tectonically stable coastlines of Australia, China and South America may be the sleeping giants of global carbon sequestration.

"Collectively, they contain half the global saltmarsh extent. A doubling of carbon sequestration in these wetlands would sequester an additional five million tonnes of atmospheric carbon per year, providing a mitigating feedback between sea-level rise and atmospheric carbon concentrations," Prof Rogers said.

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"However, this potential benefit is compromised by the ongoing clearance and reclamation of these wetlands.

"Preservation of coastal wetlands is critical if they are to play a role in sequestering carbon and mitigating climate change.”