Blue carbon horizons

Professor Neil Saintilan
Macquarie University

Dr Jeff Kelleway
University of Wollongong

Associate Professor Kerrylee Rogers
University of Wollongong

Professor Colin Woodroffe
University of Wollongong

Dr Atun Zawadzki
ANSTO - Australia's Nuclear Science and Technology Organisation

Dr Debashish Mazumder
ANSTO - Australia's Nuclear Science and Technology Organisation

Professor Patrick Megonigal
Smithsonian Environmental Research Centre

Professor Janine Adams
Nelson Mandela University, South Africa

The potential benefit of wetlands in combating climate change is compromised by ongoing clearance and reclamation.

We have advocated strongly for the inclusion of mangrove and saltmarsh restoration in emission reduction programs and, in collaboration with colleagues across the globe, achieved considerable success, as evidenced by recent initiatives such as the International Partnership for Blue Carbon.

At the national level, the Commonwealth Government has accepted our recommendations that coastal wetland restoration be pursued as a climate change mitigation strategy and are moving to a scoping phase under the Emissions Reduction Fund.

The stable coastlines of Africa, Australia, China and South America have been subject to unchanging or falling sea levels over the past few millennia. Collectively, these coastlines contain half of the global mangrove and saltmarsh extent.

These relatively old wetlands by global standards have been exposed high in the intertidal zone for centuries, making them vulnerable to oxidation and loss of carbon over time, and show lower levels of carbon than North American and European coastal wetlands.

Our research demonstrates that rather than being poor cousins in their carbon contribution, Southern Hemisphere wetlands have the potential to sequester an additional 5 million tonnes of atmospheric carbon per year if the rate of sea-level rise were to double.

At the same time, this acceleration in carbon sequestration is also a strategy that helps the wetlands adjust to sea-level rise. The value of wetland preservation and restoration in the Southern Hemisphere should not be based on existing levels of carbon, but their potential for accelerating carbon sequestration over the coming century.

• Rogers K., Kelleway J., Saintilan N., Megonigal P.,Adams J., Holmquist JR, Meng L.,Schille-Beers L., Zawadski A., Mazumder D., and Woodroffe C. (2019). Wetland carbon storage controlled by millennial-scale variation in relative sea-level rise. Nature 567: 91-95.