The ocean has begun spilling across Bill Drew’s farmland north-west of Adelaide, and he’s ecstatic. The seawater inundation of his 255ha property is an early success story within a larger project restoring saltmarsh and mangrove habitats near Webb Beach, on the eastern side of South Australia’s Gulf St Vincent.
Bill is a big, burly country bloke of few words, but he’s clearly revelling in the fish and shorebirds that have begun to appear on his newly saturated property. And he’s buoyed by how his four children, aged from 2–8 years, have been responding to the transformation of land beneath their feet since decades-old blockages were recently removed, bringing the sea back in.
“I’ve been telling everybody about it,” Bill says, conceding the land – which his father, also Bill, bought with his parents more than 40 years ago for grazing livestock – had never been particularly productive as farmland. “But now the water is back in – wow! I’ve never seen it like this before. This is about making a better future for the kids. It’s all for the kids.” One day, this newly flooding environment might also bring in money for the family.
The larger undertaking seeing Bill’s land slowly return to its former natural glory involves 156ha of wetland habitat in SA’s first registered Blue Carbon Ecosystem Restoration project. ‘Blue carbon’ is the carbon contained in vegetated coastal habitats, and it could be significant to Australia achieving its net-zero emissions target. The project near Webb Beach has been headed by not-for-profit conservation organisation The Nature Conservancy (TNC) Australia but has involved almost a dozen other key participants – a multi-organisational approach that has been integral to the success of this restoration. As the saying goes, ‘it takes a village’.
Other partners include Flinders and Adelaide university research teams, Kaurna Traditional Owners, Adelaide Plains Council, BirdLife Australia, Birds SA, local natural resources management groups, and National Parks and Wildlife Service South Australia. The latter jointly manages, with Kaurna rangers, the neighbouring Adelaide International Bird Sanctuary National Park – also known as Winaityinaityi Pangkara, a Kaurna term recognising it as ‘bird country’. The sanctuary is home to about 27,000 birds. Being at the southern end of the famed East Asian–Australasian Flyway migratory route – which links Northern Hemisphere breeding grounds with feeding grounds at the other end of the world – it’s also globally important for dozens of migratory species.
Kaurna Elder Uncle Jeffrey Newchurch, now in his 60s, grew up near this place. He moved away for a while but returned, mindful he holds much cultural knowledge that he has a responsibility to pass on. He recalls shadowing his dad and aunties here as a child, learning about the local animal and plant life and the ways of Country.
Tread the saltmarshes, mudflats and mangroves of Winaityinaityi Pangkara with Uncle Jeffrey and his deep connection to this area is palpable. “When you walk Country in silence, Country opens up to you. Country lets you know,” he says as he strides quietly over the damp ground, his long, grey beard fluttering in a strong onshore breeze as the calls of seabirds fill the air. “This place has always been significant. My father and the old people taught me about the birds. They’re a calendar to us; [they tell us] the seasons. You get to know them and their habits and, hopefully, learn some of their ways.”
As this land continues to heal after the removal of tidal blockages that interfered with its natural rhythms for decades, it’s hoped it will bring huge cultural benefits for new generations of Kaurna.
Funding boost
Bill’s dad, who has passed away, began working with TNC back in 2019 when they first started coastal restoration around Webb Beach. But in 2022, the work got a massive nudge forward thanks to $2.9 million in federal funding under the Blue Carbon Ecosystem Restoration Grants. “The intention was to pilot ‘the blue carbon method’ [of capturing and locking away carbon] here and see how we could run through every step, right from the feasibility stage to implementing a permanent reconnection to the sea,” explains Kylie Moritz, conservation coordinator at TNC. “Because these projects don’t work in isolation, it was a whole-of-landscape approach that we needed to take.”
The true potential of the site to store huge amounts of blue carbon won’t be fully realised for decades. But it’s the multiple co-benefits created by this restoration project that make it more immediately valuable. Those, of course, include the already-evident cultural benefits. But sampling and monitoring are showing that restoring the saltmarshes, by bringing them back under tidal influence, has also begun to reap many biodiversity rewards. “Much of this wetland site hadn’t had seawater-flushing events for 50 years. So as freshwater from rainfall settled on it and evaporated, it drew salt up into the top layer [of sediment] so plants couldn’t grow,” Kylie says, adding that this meant the saltmarshes became lifeless salt pans. “But we can already see that salt is being flushed out, which means we might get plants becoming established by this spring…much quicker than what we expected.”
Sampling has also shown that, in nearby tidal creeks, diverse fish and crustaceans – including commercially important species such as whiting, mullet, garfish, black bream, flounder, congolli, western king prawn and blue crab – were present. Analyses undertaken in partnership with SA Research and Development Institute, Flinders University and the University of Newcastle indicate that saltmarsh vegetation provided important nutrition and a food source for some of these species. “This indicates the flow-on impacts on local animal species of regenerating saltmarsh vegetation are likely to be huge, passing right along not only local food chains but way beyond,” says Flinders University marine biologist Professor Sabine Dittmann.
What’s more, there’s strong evidence the restoration here will help futureproof this coastline against predicted sea-level rising. Ecological modelling shows that as the sea level rises, the saltmarsh here will transition into mangrove forest, and that will help secure the shore.
Capturing carbon
What sets blue carbon apart from any other carbon? Chemically speaking, not a lot. The term appeared in scientific literature from about 2009 as part of the ever-expanding lexicon around climate change. It specifically relates to carbon contained in marine ecosystems – notably mangrove forests, seagrass beds and saltmarshes.
To appreciate why that might be significant, it’s useful to revisit the basic biological principle that all green plants absorb carbon dioxide from the atmosphere during the process of photosynthesis and use the carbon component to build their roots, stems and trunks. It’s this that makes living green vegetation – in either terrestrial or aquatic habitats – a natural storehouse for carbon.
“Photosynthesis is still the best carbon capture mechanism we know of,” says marine ecologist Dr Mat Vanderklift, a leading blue carbon researcher with CSIRO. “And so far, humans haven’t invented anything better than what nature already does well.”
It’s what makes the massive cool temperate forests of the Northern Hemisphere and the tropical rainforest of the Amazon so critical to the health of the planet. These huge terrestrial forested places are literally massive life-support systems for the planet because they release oxygen while sucking in carbon dioxide. But, very importantly, they also sequester massive amounts of that carbon, keeping it out of the atmosphere where it drives climate change. The kicker, of course, is that when this vegetation dies, it releases all the carbon it contains back into the atmosphere.
“So, plants take carbon out of the atmosphere and put it in wood. And if it’s in wood, it’s not in the atmosphere. That’s good for climate change,” Mat says. “But collectively, as scientists, once we began looking closer, it was clear that a lot of carbon also goes into the soil.” In terrestrial systems – such as forests and woodlands – it doesn’t stay in the soil for long because it’s usually broken down quickly by organisms such as bacteria, fungi and earthworms. “On land, there are all these decomposers in the soil, and you give them a bit of carbon and that’s like food, and they’ll munch through it,” Mat says. “But these coastal wetlands systems have conditions that are conducive to carbon staying in the soil.”
And the regular bathing of these places by saltwater delivered by tides is the reason why. “These [decomposer] organisms respire like we do, taking in oxygen and breathing out carbon dioxide,” Mat continues. “But in salty coastal ecosystems, the decomposers tend not to get the oxygen they need, so they can’t decompose as fast.” The result is that carbon tends to remain locked away in the soils of these systems for considerably longer. And the reason that has had climate scientists so interested is because it turns out that healthy coastal wetlands – blue carbon systems – have the capacity to store more carbon per unit area than land-based forests.
Australia, of course, has large tracts of important woodlands and forests, many of which are significant on a global stage for various reasons. As carbon stores, however, these places can’t match what’s available in other countries in terms of total area.
But blue carbon is a different story.
Co-benefits
Few other countries have Australia’s blue carbon stores. Firstly, we have a lot of blue carbon habitat (see map below). With 59,681km of coastline (including Tasmania and offshore island territories) according to Geoscience Australia – the sixth longest in the world – Australia has more mangrove, seagrass and saltmarsh habitat than most nations. Secondly, Australia’s collective scientific knowledge in this space is huge. In fact, when it comes to scientists with blue carbon and coastal ecosystem expertise, we punch considerably above our weight internationally.
That’s probably not surprising when you consider the strong connection to the coast that so many Australians have. According to the Australian Bureau of Statistics, 85 per cent of our population lives within 50km of the coastline, suggesting that – culturally, at least – there’s a lot of vested interest in maintaining and resurrecting the health of coastal habitats. These vegetated tidal places have had, and still have, a massive cultural connection to First Nations people across multiple millennia, particularly because of the high biodiversity and food resources they contain. And today these places are also prized for their recreational and lifestyle roles, and as natural systems of great scenic beauty.
But, perhaps even more importantly, a healthy fringe of coastal wetland habitat is fundamental to the way this country functions. For example, these places act like kidneys, filtering out impurities from coastal environments. They also hold together and stabilise the coast against sea surges and storms, provide habitat and food for coastal animals – from fish to birds – and act as protected nursery sites for the young of marine creatures that often grow to adulthood in waters way beyond our shores.
Being Australia’s largest national research organisation tasked with finding answers to some of the country’s most pressing environmental problems, CSIRO began seriously looking into blue carbon and its potential just over a decade ago. “At the time, all the data was coming out of the Northern Hemisphere, and we really didn’t know what the potential was in Australia,” says blue carbon expert Dr Andy Steven, who was then tasked by CSIRO with leading a national consortium of relevant researchers to collate all available blue carbon information. It led to a landmark scientific paper, Australian vegetated coastal ecosystems as global hotspots for climate change mitigation, published in Nature Communications and written by dozens of Aussie experts spearheaded by lead author Dr Oscar Serrano from Edith Cowan University’s Centre for Marine Ecosystems Research.
Ever since, Mat and Andy have been leading CSIRO’s rising exploration of the potential of blue carbon, not only in Australia but with many nations across the Indo–Pacific. The work there is providing the science underpinning how blue carbon can contribute to climate change mitigation, while also improving livelihood opportunities for communities with a dependence on, and custodial responsibility for, ensuring the health of coastal ecosystems.
The CSIRO team laid the foundation for the development of the ‘tidal restoration of blue carbon ecosystems method’ for Australia’s Clean Energy Regulator – a way to measure, and potentially monetise, how much carbon is captured in wetland systems. It’s the latest ‘method’ to be approved in Australia as a way of ‘farming carbon’ to incentivise landholders to protect and resurrect natural ecosystems.
The opportunity to farm carbon for financial return was first made available to landholders in Australia in 2011 through the federal Carbon Farming Initiative, now the Australian Carbon Credit Unit (ACCU) scheme. Landholders can register approved land-use activities with the Clean Energy Regulator and earn ACCUs – tradeable carbon credits – by either preventing the production of atmospheric carbon or by drawing it down from the atmosphere and locking it away. One ACCU represents one tonne of carbon and is presently worth about $35.
Believing blue carbon ecosystems might help to offset global carbon dioxide emissions, the CSIRO team set out in 2022, with funding from industrial giant BHP, to map the blue carbon restoration potential around Australia – “to measure and quantify the net emissions reduction potential of Australia’s mangroves, seagrasses and saltmarshes”. What particularly interests organisations such as BHP in these sorts of projects is the potential they offer as carbon-offset opportunities.
For CSIRO, Mat says, there were two major motivations for the project. “One was [to identify] how much carbon abatement we could get if you applied [the method] everywhere in Australia that you could do it,” he says. “And then [to identify] whether the kind of cost benefit was worthwhile.” In that way it could let landholders know, for example, whether the long-term expense of removing floodgates and resurrecting original wetland habitat would be financially worth it.
It turns out most potential lies in northern Australia, notably parts of Queensland, the Northern Territory and Western Australia. “For example, there’s this ‘ponded pasture’ system in a lot of north-eastern Australia, where essentially the tides are kept out with a kind of wall or barrier,” Mat says. “But when it rains, it turns into a mostly freshwater area that tends to generate a lot of methane and other greenhouse gases. So, if you let the tide back in, you stop producing those other greenhouse gases, as well as getting the carbon back.”
The downside is that ponded pastures tend to be highly productive and protect beef producers against drought. And those farmers aren’t interested, anyway, in carbon when they can grow cattle.
Andy points out that traditional approaches of measuring blue carbon potential were limited – including the widely used ‘bathtub’ approach, which simply assesses where water goes if you fill a landscape with it. “[That is] not particularly accurate,” Andy says. “So, we came up with a much more resolved and reliable method of looking at how far the inundation is likely to go across land.” This improved inundation mapping method has been one of the most groundbreaking outcomes of the work.
“The other innovative aspect,” Andy continues, “was combining that with economic modelling to be able to say across different land uses that, if a certain area was inundated, how it would stack up when you consider other factors like the value of the land, the price of carbon, and the establishment costs [of a rehabilitation program].” This recently completed mapping project is valuable not only for policymakers but also landholders, developers and anyone else looking to make decisions about coastal land-use.
“No one is pretending blue carbon is a silver bullet that’ll solve climate change, because you can’t do that without dealing with the fossil fuel issue,” Mat says. In fact, he adds that if all blue carbon sites worldwide were recovered and maintained, the carbon they’d lock away would represent only about 3 per cent of global emissions. That’s equivalent to the emissions of the global airline industry.
“We haven’t yet got a sustainable aviation fuel, so we’re going to be using jet fuel for some time yet,” Mat says. “So, while we’re still trying to solve those sorts of things, [blue carbon] is a contribution.”
Helping the GBR
While Mat and Andy grapple with the practical challenges of mapping, modelling and quantifying Australia’s blue carbon potential, the Great Barrier Reef Foundation (GBRF) has been exploring how the nascent blue carbon marketplace could help safeguard the troubled reef. It sees blue carbon as part of the ultimate solution to climate change-driven mass coral bleaching. Restoring blue carbon ecosystems would also contribute to improving water quality because they trap sediments and nutrients that can run off from agricultural land.
For now, however, it’s the co-benefits of blue carbon-based habitat restoration – like healthier coastal ecosystems – that are of most interest. When all things are considered – for example, the cost of removing tidal barriers to encourage mangroves back onto floodplains versus the value of farming cattle and sugarcane on the same floodplains – the economics for blue carbon over much of Queensland just don’t yet stack up. But the foundation believes there’s significant potential in restoring lost or damaged seagrass meadows along the reef – habitats known to lock away large amounts of carbon in sediments – though no carbon-credit method exists yet for seagrass restoration.
Seagrass restoration can be laborious, time-consuming and extremely expensive, requiring the transplant of individual plants. But, says Will Hamill, the GBRF’s director of coastal habitat restoration, a world-first seagrass planting project by Central Queensland University’s Coastal Marine Ecosystems Research Centre is showing enormous potential trialling a new scalable way of sowing seagrass. “At the port of Gladstone, we’ve invested in a large seagrass nursery – the biggest in the world – as a demonstration for seed-based seagrass restoration,” Will says. “It’s like a knowledge hub to share how this technique works, and it’s supporting a number of seagrass restoration sites in that region.”
On the Maroochy
Meanwhile, not far from one of Australia’s fastest-growing urban areas in Southeast Queensland, another significant blue carbon project has been attracting a lot of attention. Appropriately named Blue Heart, it encompasses about 5000ha on the lower floodplain of the Maroochy River. It too was a recipient of one of the federal government’s five Blue Carbon Ecosystem Restoration Grants – in this case, $2,036,000.
The Blue Heart area was, for much of last century, dominated by agricultural activities – notably sugarcane farming, which began declining as profit margins tightened after the nearby Moreton Central Sugar Mill, in the town of Nambour, closed in 2003. Being in the subtropics, the verdant vegetation of Blue Heart looks vastly different to what grows at the Gulf St Vincent blue carbon site in SA. But the blue carbon approach here shares many similarities with that site, especially in terms of its complex logistics and multi-partnered approach.
The Blue Heart blue carbon project is spearheaded by the local Sunshine Coast Council, but other active partners include the area’s Kabi Kabi Traditional Owners, local utility Unitywater, the Queensland Government, TNC, and researchers from the University of the Sunshine Coast, The University of Queensland, Griffith University and the University of New South Wales. As is the case at the SA site, tidal flows in the low-lying Blue Heart precinct have been altered for decades by floodgates, some of which are now being removed. Even with floodgates in place, flooding has long been a problem for the area and has become worse this century with shifting rainfall patterns linked to climate change. It’s predicted the area will be completely inundated due to sea-level rise by 2100.
“We’ve already seen a lot of tidal inundation out there,” says senior environment project officer with the Sunshine Coast Council, Dr Sonia Marshall, who’s managing the project. “About one-third of the Blue Heart area is publicly owned land – so it’s owned by a government entity – and the rest is privately owned land. There are a number of projects happening in the Blue Heart to try to support the landholders who live there and [to encourage continued] recreational opportunities.
“But for now, the blue carbon project is only happening on council-owned land. It’s a trial to test the feasibility of the blue carbon farming method, to see if it’s something that landholders here might be able to use in the future when tidal inundation becomes even more prominent.”
For Sonia, however, the real value of the Blue Heart project has been the extraordinary cooperation it has ignited across the carbon industry – including not-for-profits, academic institutions, government, and carbon-related businesses – and the co-benefits that are already starting to be seen. These include the return of mullet and other fish to the tidal creeks and rivers in the area. Anecdotally, water birds are also increasing, with recent reports of brolgas and jabiru storks that haven’t been seen here in years. Black swans, which First Nations stories suggest used to be plentiful in the area but have rarely been seen in recent years, are returning in larger numbers.
“Most people have known about the benefits of coastal wetlands for decades, but putting carbon [into the equation] alerts governments to their importance,” says The University of Queensland marine ecologist Professor Catherine Lovelock, one of Australia’s leading blue carbon experts and someone who knows the Maroochy River site well. “The Blue Heart is a great collaboration because the Queensland Government, federal government and local governments all got involved. And it has a consortium of researchers all with the same sort of interest, and it stimulated more involvement with the Kabi Kabi. The tangible benefits here, like fishing and recreation, shouldn’t be undersold. All of that collaborative kind of action is really worth a lot. So, relationships have started that will help them solve other problems.”
Adaptation to sea-level rise is already a big issue for coastal Australia, Catherine adds, and is only going to get bigger and more expensive. That means restoration of these ecosystems is hugely important to how that problem is dealt with. “Increasing the flood volume on the landscape to slow things down to soak up that water – wetlands are good at that,” she says. “Since colonisation, [we have] removed a lot of that capacity.”
Kerry Jones, a Kabi Kabi Elder closely involved with the Blue Heart project, was born and raised on the Maroochy River. “My great-grandmother was probably one of the last full-blood ladies to live on this river [in 1917], and she played a major role here,” Kerry recalls. “Some of the old cane farmers down near the river mouth said she used to sell fish, and mud crab, and native bush flowers in exchange for tobacco and flour.”
The Maroochy River, he says, was his backyard. “I was always with my father, learning how to fish, hunt crab – and when he wasn’t teaching me, I was following him, watching and observing,” Kerry says. “We knew certain trees that were indicators for fish, crustaceans and molluscs. When these flowered, we knew these resources were coming in to season; this fish will be here in abundance when this one comes into flower. Our people moved around, followed them seasonal indicators and knew not to flog it – exhausting all them resources in one area all the time.”
He’s optimistic the Blue Heart project will release the pressure that has been facing this habitat for many years. “Our children need to reconnect with that, and I’d love it if we could have more Kabi people on Country to have that connectivity,” Kerry says.
“I think that, as a human race, we’ve got to be in touch with Mother Nature more instead of destroying [her] – because once it’s gone past a certain level, it’s very hard to bring something back.”