Peter Macreadie

• PhD
• Head of Department at RMIT University

Blue carbon ecosystems (BCEs) exhibit remarkable capacities for organic carbon (C) storage, making them a promising nature‐based climate solution. However, the lack of robust, spatially explicit estimates of C stocks in BCEs presents a major challenge to incorporating them into national and global C accounting and climate mitigation strategies. For...

South Korea has made significant commitments to pursuing marine carbon sequestration [including ‘blue carbon’] initiatives as part of its broader environmental and climate strategies. Specifically, the South Korean government has set a target to sequester 1,362,000 tonnes of CO₂ in the ocean by 2050 as part of its national strategy. Here, leveragin...

Globally, coastal wetlands such as mangroves and saltmarshes are in decline. With many coastal wetlands dispersed across privately owned lands, one strategy to promote their protection is through private land coastal wetland programs. While landholder engagement is key to developing such programs, little is known about how landholders interact with...

Mangrove forests around the world are under significant pressure from climate change (e.g., rising sea levels), and human-related anthropogenic activities (e.g., coastal infrastructure development). Mangrove restoration projects have increased over the past decades but seedling and propagule survival rates are reportedly low, while many projects ha...

Amid global biodiversity and climate crises, restoring blue carbon ecosystems (BCEs) like mangroves, tidal marshes, and seagrass may offer multiple biodiversity and climate benefits. However, species-specific information on BCE use remains unconsolidated and often inaccessible to land managers. Here we compile a database and examine broad ecologica...

Blue carbon ecosystems (BCEs) represent a significant natural solution for climate change mitigation through their capacity to sequester large amounts of organic carbon. These coastal habitats also provide an array of co-benefits, such as biodiversity enrichment, livelihood support, and opportunities for tourism and recreational activities. However...

Mangrove loss has reduced its carbon (C) sink function and ecosystem services. To effectively allocate climate finance for mangrove restoration, a thorough assessment of restoration potential is necessary. Here we show a net loss of ecosystem service value (ESV) of 29.2 billion USD ($) due to land changes in mangroves from 1996 to 2019. The estimat...

While seagrass ecosystems are acknowledged for their role as blue carbon sinks, significant uncertainties remain regarding the sequestration of sediment inorganic carbon (SIC) and its broader implications for carbon cycling. These knowledge gaps hinder a comprehensive assessment of the contribution of seagrass ecosystems to the global carbon budget...

Blue carbon (BC) habitats (e.g., mangroves, tidal marshes, and seagrasses) are important CO2 sinks but are among the most threatened ecosystems on Earth. Substantial research over the last decade has quantified BC to evaluate the climate benefits associated with habitat conservation and restoration. However, the exponential growth in BC science has...

Understanding the complex dynamics of greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes in terrestrial and aquatic ecosystems requires extensive monitoring campaigns to capture spatial and temporal variations adequately. However, conventional commercial GHG analysers limit data collection due to the...

Seaweed farming has emerged as a potential Blue Carbon strategy, yet empirical estimates of carbon burial from such farms remain lacking in the literature. Here, we quantify carbon burial in 20 seaweed farms distributed globally, ranging from 2 to 300 years in operation and from 1 to 15,000 ha in size. The thickness of sediment layers and stocks of...

Coastal ecosystems provide critical ecosystem services, including carbon sequestration and coastal protection, yet face continuing global decline. In areas where natural revegetation is impeded (e.g., altered hydrodynamics, substrate instability, erosion), active restoration techniques using artificial structures like Biodegradable Elements for Sta...

The integration of blue carbon (BC) into the voluntary carbon market promotes BC ecosystem management through financial incentives. We analysed 70 BC projects and present a comprehensive knowledge synthesis on a multifaceted BC sector and its contribution toward sustainable development. Currently, market‐based BC projects are located across 29 coun...

Seaweed aquaculture is growing 8.9 % annually to a forecast US$ 22.13 billion in 2024 and has several environmental, economic and social co-benefits. A proposed approach to expanding seaweed aquaculture is to develop offshore aquaculture. However, the costs of the infrastructure remain a key barrier. Reducing costs by growing seaweed on obsolete oi...

Patchy global data on belowground litter decomposition dynamics limit our capacity to discern the drivers of carbon preservation and storage across inland and coastal wetlands. We performed a global, multiyear study in over 180 wetlands across 28 countries and 8 macroclimates using standardized litter as measures of “recalcitrant” (rooibos tea) and...

Mangroves are important organic carbon (OC) reservoirs that adapt to climate changes. Although sedimentary dissolved organic matter (SDOM) has been established as a dominant OC component within these ecosystems, its molecular composition, origin, and fate remain largely unknown. This study examined SDOM molecules from one of the largest peri-urban...

One of the world’s largest “blue carbon” ecosystems, Louisiana’s tidal wetlands on the US Gulf of Mexico coast, is rapidly being lost. Louisiana’s strong legal, regulatory, and monitoring framework, developed for one of the world’s largest tidal wetland systems, provides an opportunity for a programmatic approach to blue carbon accreditation to sup...

Combating climate change and achieving the UN Sustainable Development Goals (SDGs) are two important challenges facing humanity. Natural climate solutions (NCSs) can contribute to the achievement of these two commitments but can also generate conflicting trade‐offs. Here, we reviewed the literature and drew on expert knowledge to assess the co‐bene...

Mangrove restoration involves complex decision-making processes and can often lack adequate stakeholder engagement and empowerment to inform effective restoration outcomes. Decision science has the potential to overcome such challenges by facilitating structured approaches to make informed, participatory, and defensible decisions through the use of...

Blue carbon ecosystems (BCEs), such as mangroves, saltmarshes, and seagrasses, are important nature-based solutions for climate change mitigation and adaptation but are threatened by degradation. Effective BCE restoration requires strategic planning and site selection to optimise outcomes. We developed a Geographic Information System (GIS)-based mu...

Spatial quantification of blue carbon ecosystem stocks is crucial for developing policies to mitigate climate change, especially in regions experiencing ongoing wetland disturbance from biological invasions. We integrated multiple machine learning models with the space-for-time substitution method to quantify the spatiotemporal impact of Spartina a...

Coastal and marine ecosystems provide valuable ecosystem services and functions. Unfortunately, these habitats have experienced increasing anthropogenic and climate‐related pressures, leading to significant degradation and loss not only in Australia but also globally. Hence, the urgency for coastal and marine ecosystem restoration has never been mo...

The Pondi loggers address significant logistical and methodological challenges in monitoring carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes in terrestrial and aquatic ecosystems. Given the intricate dynamics of carbon and nitrogen cycles, achieving precise quantification of their fluxes requires extensive, prolonged monitoring...

Agricultural ponds are a significant source of greenhouse gases, contributing to the ongoing challenge of anthropogenic climate change. Nations are encouraged to account for these emissions in their national greenhouse gas inventory reports. We present a remote sensing approach using open-access satellite imagery to estimate total methane emissions...

Photoautotrophic marine ecosystems can lock up organic carbon in their biomass and the associated organic sediments they trap over millennia and are thus regarded as blue carbon ecosystems. Because of the ability of marine ecosystems to lock up organic carbon for millennia, blue carbon is receiving much attention within the United Nations' 2030 Age...

The United Nations has declared 2021–2030 as the Decade on Ecosystem Restoration and the Decade of Ocean Science for Sustainable Development. These declarations emphasise the importance of restoring degraded marine and coastal ecosystems and supporting research and knowledge. The number and scale of marine and coastal restoration projects have been...

Blue carbon is fast garnering international interest for its disproportionate contribution to global carbon stocks. However, our understanding of the size of these blue carbon stocks, as well as the provenance of carbon that is stored within them, is still poor. This is especially pertinent for many small-island nations that may have substantial bl...

Wetlands are characterised by soils rich in organic matter that accumulate carbon, providing an important pathway for carbon dioxide sequestration. Nevertheless, not all the carbon fixed can be accumulated, and a proportion will decompose through microbial consumption and be partly released into the atmosphere. Rates of organic matter decomposition...

Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organ...

Mangroves play a globally significant role in carbon capture and storage, known as blue carbon ecosystems. Yet, there are fundamental biogeochemical processes of mangrove blue carbon formation that are inadequately understood, such as the mechanisms by which mangrove afforestation regulates the microbial‐driven transfer of carbon from leaf to below...

Invasive Spartina alterniflora has become a global management challenge in coastal wetlands. China has decided to eradicate it completely, but the high costs and its provision of beneficial ecosystem functions (EF, in the form of blue carbon and coastal protection) have raised concerns about its removal. Here, using the Yangtze Estuary as a case st...

The Blue Carbon Accounting Model (BlueCAM) is a tool for tidal restoration projects established under the Tidal Restoration for Blue Carbon method (2022) of the Australian voluntary carbon market. The commentary of Gallagher discussed that Blue-CAM did not subtract allochthonous carbon, which is carbon in wetland soils from external sources, either...

Blue carbon ecosystems (BCEs), such as mangroves, saltmarshes, and seagrasses, are increasingly recognized as natural climate solutions. Evaluating the current extent, losses, and gains of BCEs is crucial to estimating greenhouse gas emissions and supporting policymaking. Remote sensing approaches are uniquely suited to assess the factors driving B...

Seagrass meadows are declining at a global scale, threatening their capacity as blue carbon sinks. Restoration of seagrasses (via seagrass seeds or plant transplantation) may recover their carbon sequestration capacity. Previous studies have predominantly focused on sediment organic carbon (SOC), while variations in sediment carbon compositions rem...

Coastal saltmarshes provide globally important ecosystem services including 'blue carbon' sequestration, flood protection, pollutant remediation, habitat provision and cultural value. Large portions of marshes have been lost or fragmented as a result of land reclamation, embankment construction, and pollution. Sea level rise threatens marsh surviva...

The soil in terrestrial and coastal blue carbon ecosystems is an important carbon sink. National carbon inventories require accurate assessments of soil carbon in these ecosystems to aid conservation, preservation, and nature-based climate change mitigation strategies. Here we harmonise measurements from Australia’s terrestrial and blue carbon ecos...

Seaweed (macroalgae) has attracted attention globally given its potential for climate change mitigation. A topical and contentious question is: Can seaweeds' contribution to climate change mitigation be enhanced at globally meaningful scales? Here, we provide an overview of the pressing research needs surrounding the potential role of seaweed in cl...

The role of macroalgae (seaweed) as a global contributor to carbon drawdown within marine sediments - termed 'blue carbon' - remains uncertain and controversial. While studies are needed to validate the potential for macroalgal‑carbon sequestration in marine and coastal sediments, fundamental questions regarding the fate of dislodged macroalgal bio...

Artificial waterbodies can help tackle the ongoing freshwater biodiversity crisis by providing new habitat for aquatic wildlife. Farm dams are among the most abundant artificial waterbodies in agricultural landscapes, yet general guidelines for maximising their ecological potential are yet to emerge. Here we used a continental-scale dataset of frog...

The restoration of seagrass habitats is a relatively young field with several successful restoration attempts highlighting the feasibility of large‐scale restoration. Successful restoration of seagrass habitats requires an understanding of the most appropriate techniques to use for the target species and local conditions of restoration sites, howev...

Vegetated coastal ecosystems, in particular mangroves, tidal marshes and seagrasses are highly efficient at sequestering and storing carbon, making them valuable assets for climate change mitigation and adaptation. The state of Queensland, in northeastern Australia, contains almost half of the total area of these blue carbon ecosystems in the count...

Thousands of oil and gas structures have been installed in the world's oceans over the past 70 years to meet the population's reliance on hydrocarbons. Over the last decade, there has been increased concern over how to handle decommissioning of this infrastructure when it reaches the end of its operational life. Complete or partial removal may or m...

The suggestion that seaweed farming contribute to carbon sequestration below the farms was tested by quantifying, combining organic carbon density with sediment accumulation estimates in soils below seaweed farms, in 21 seaweed farms distributed globally, ranging up to 300 years in operation and 15,000 ha in size. One in every four farms sampled wa...

Agricultural ponds have some of the highest methane emissions per area among freshwater systems, and these anthropogenic emissions should be included in national greenhouse gas inventories. Here we deliver a continental-scale assessment of methane emissions from agricultural ponds in the United States and Australia. We source maps of agricultural p...

Blue (coastal wetlands) and teal (inland wetlands) carbon ecosystems are long-term carbon sinks and are regarded as essential natural climate solutions. Yet, the same biogeochemical conditions favoring high carbon storage also promote the production of two potent greenhouse gases (GHGs)—methane and nitrous oxide—which can reduce the climate change...

The Gippsland Basin is the location of Australia’s oldest offshore oil and gas (O&G) structures, with hydrocarbon production beginning in the 1960s. The Bass Strait flows over this area with fisheries providing seafood for the major population centers of Melbourne, Sydney and beyond. Since Australia’s maritime legislation restricts activities to ou...

There have been discussions of scaling up offshore seaweed cultivation and sinking it exclusively for carbon sequestration (‘ocean afforestation’) and thereby help mitigate climate change, but is this concept feasible? Here we investigate the feasibility of ocean afforestation across five perspectives: 1) Ecological feasibility; 2) Technical feasib...

‘Blue carbon’ was coined over a decade ago to describe the contribution of mangroves, seagrasses, and tidal marshes to carbon drawdown in coasts and oceans, concomitantly attracting attention of policy-makers and resource managers to their potential as a natural climate solution. Here, we explore the emergence and evolution of this relatively new r...

The capacity of Blue Carbon Ecosystems to act as carbon sinks is strongly influenced by the metabolism of soil-associated microbes, which ultimately determine how much carbon is accumulated or returned to the atmosphere. The rapid evolution of sequencing technologies has facilitated the generation of tremendous amounts of data on what taxa comprise...

Our knowledge of the factors that can influence the stock of organic carbon (OC) that is stored in the soil of seagrass meadows is evolving, and several causal effects have been used to explain the variation of stocks observed at local to national scales. To gain a global‐scale appreciation of the drivers that cause variation in soil OC stocks, we...

Seagrass restoration requires information on a range of factors including site environmental conditions, appropriate planting techniques, and the identification of sites most likely to support seagrass. To address the question of where to focus restoration efforts, a key first step is to identify trends in the spatio‐temporal distribution of seagra...

Natural climate solutions are crucial interventions to help countries and companies achieve their net-zero carbon emissions ambitions. Blue carbon ecosystems such as mangroves, seagrasses, and tidal marshes have attracted particular attention for their ability to sequester and store carbon at densities that can far exceed other ecosystems. The scie...

The biodiversity of marine and coastal habitats is experiencing unprecedented change. While there are well-known drivers of these changes, such as overexploitation, climate change and pollution, there are also relatively unknown emerging issues that are poorly understood or recognized that have potentially positive or negative impacts on marine and...

Restoration of coastal wetlands has the potential to deliver both climate change mitigation, called blue carbon, and adaptation benefits to coastal communities, as well as supporting biodiversity and providing additional ecosystem services. Valuing carbon sequestration may incentivise restoration projects, however, it requires development of rigoro...

Agricultural practices have created tens of millions of small artificial water bodies (“farm dams” or “agricultural ponds”) to provide water for domestic livestock worldwide. Among freshwater ecosystems, farm dams have some of the highest greenhouse gas (GHG) emissions per m2 due to fertilizer and manure run‐off boosting methane production – an ext...

Blue Carbon Ecosystems (BCEs) help mitigate and adapt to climate change but their integration into policy, such as Nationally Determined Contributions (NDCs), remains underdeveloped. Most BCE conservation requires community engagement, hence community-scale projects must be nested within the implementation of NDCs without compromising livelihoods o...

Ecosystem accounting is a structured approach to compiling environmental and economic information. While accounts are typically used to compile data on past trends, they have an unrealised capacity to also be used to inform decisions by providing a structured approach to scenario evaluation of potential futures. We used the global standard for ecos...

The global carbon sequestration and avoided emissions potentially achieved via blue carbon is high (∼3% of annual global greenhouse gas emissions); however, it is limited by multidisciplinary and interacting uncertainties spanning the social, governance, financial, and technological dimensions. We compiled a transdisciplinary team of experts to elu...

Agricultural practices have created tens of millions of small artificial water bodies (“farm dams” or “agricultural ponds”) to provide water for domestic livestock worldwide. Among freshwater ecosystems, farm dams have some of the highest greenhouse gas (GHG) emissions per m2 due to fertilizer and manure run-off boosting methane production – the se...