Gabriel Grimsditch’s research while affiliated with United Nations Organization and other places

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 support restoration of these ecologically and economically important tidal wetlands. Louisiana’s coastal wetlands span ∼1.4 million ha and accumulate 5.5–7.3 Tg yr⁻¹ of blue carbon (organic carbon), ∼6%–8% of tidal marsh blue carbon accumulation globally. Louisiana has a favorable governance framework to advance blue carbon accreditation, due to centralized restoration planning, long term coastal monitoring, and strong legal and regulatory frameworks around carbon. Additional restoration efforts, planned through Louisiana’s Coastal Master Plan, over 50 years are projected to create, or avoid loss of, up to 81,000 ha of wetland. Current restoration funding, primarily from Deepwater Horizon oil spill settlements, will be fully committed by the early 2030s and additional funding sources are required. Existing accreditation methodologies have not been successfully applied to coastal Louisiana’s ecosystem restoration approaches or herbaceous tidal wetland types. Achieving financial viability for accreditation of these restoration and wetland types will require expanded application of existing blue carbon crediting methodologies. It will also require expanded approaches for predicting the future landscape without restoration, such as numerical modeling, to be validated. Additional methodologies (and/or standards) would have many common elements with those currently available but may be beneficial, depending on the goals and needs of both the state of Louisiana and potential purchasers of Louisiana tidal wetland carbon credits. This study identified twenty targeted needs that will address data and knowledge gaps to maximize financial viability of blue carbon accreditation for Louisiana’s tidal wetlands. Knowledge needs were identified in five categories: legislative and policy, accreditation methodologies and standards, soil carbon flux, methane flux, and lateral carbon flux. Due to the large spatial scale and diversity of tidal wetlands, it is expected that progress in coastal Louisiana has high potential to be generalized to similar wetland ecosystems across the northern Gulf of Mexico and globally.

Management of Marine Protected Areas can be supported by a detailed understanding of ecosystem state. We assessed coral reefs within Pemba Channel Conservation Area in 2019 and evaluated changes over the previous decade. In 2019, hard coral cover ranged from 3.5 % to 58.4 % across sites, while coral recruitment was exceptionally high in places (14 recruits/m2). The highest total fish biomass was ∼ 500 kg/ha, which is low compared to forereefs elsewhere in the Western Indian Ocean. Between 2009 and 2019, benthic substrate shifted to higher soft coral and turf algae cover, and mean fish density significantly decreased. This suggests that overfishing is a major threat and some reefs will require restoration to facilitate recovery. However, Pemba's unique geomorphology might offer refuge for corals from future warming and habitat for large, endangered fishes such as groupers. This could elevate the global significance of Pemba's reefs and should motivate investment in management and conservation of these resources.

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 or social justice. Thirty-three experts, drawn from academia, project development and policy, each developed ten key questions for consideration on how to achieve this. These questions were distilled into ten themes, ranked in order of importance, giving three broad categories of people , policy & finance , and science & technology . Critical considerations for success include the need for genuine participation by communities, inclusive project governance, integration of local work into national policies and practices, sustaining livelihoods and income (for example through the voluntary carbon market and/or national Payment for Ecosystem Services and other types of financial compensation schemes) and simplification of carbon accounting and verification methodologies to lower barriers to entry.

Ocean ecosystems play a key role in maintaining the integrity of our biosphere, but vary widely with respect to their biodiversity attributes, their relationship with the atmosphere and climate change processes, and the ecosystem services that they provide to humans. Coral reefs and ecologically associated coastal ecosystems, such as intertidal mangrove forests and seagrass meadows, are complex systems that are often managed together but are also subject to different governance frameworks. The implementation of the UN Framework Convention on Climate Change’s Paris Agreement and development of global biodiversity goals and targets under the Convention on Biological Diversity offer examples of these governance challenges, but they also offer significant opportunities to maximize biodiversity outcomes while building on increasing support for nature-based solutions to climate change mitigation and adaptation. This whitepaper summarizes the scientific and policy consensus at the ocean-climate nexus, specifically with respect to the role of coral reefs and closely associated tropical coastal ecosystems in climate change processes, and explicitly identifies gaps within key intergovernmental climate and biodiversity policy frameworks that must be addressed to maximize their potential as nature-based solutions during a key decade of conservation action. It concludes with recommendations for national governments and other stakeholders.

The Western Indian Ocean (WIO) region comprises almost 6% (about 15,180 km2) of the total global area of coral reefs, and the region is a globally important hotspot for coral reef biodiversity. The WIO includes sovereign states along the eastern and southern African mainland (Somalia, Kenya, Tanzania, Mozambique, South Africa), island states (Mauritius, Madagascar, Comoros, Seychelles), as well as overseas territories (Reunion, France). The human population has grown considerably during the last century, with the states named now supporting ca. 220 million people, of which some 69 million live within 100 km of the coastline. Coral reef ecosystems underpin the economies of the countries in the region, particularly through the fisheries and tourism sectors, and provide livelihood opportunities and income for local communities estimated at US$8.4 billion annually. WIO coral reefs are estimated to have an asset value of U$ 18.1 billion. The GCRMN WIO region is a distinct biogeographic province comprised of 10 marine ecoregions, which have been combined into five subregions for this analysis.

Seagrass meadows deliver multiple ecosystem services that are of particular importance to resource-poor coastal communities, yet they are rapidly declining globally. The Payments for Ecosystem Services (PES) approach has been used to fund the protection of other ‘Blue Carbon’ Ecosystems (BCE), yet seagrass has been incorporated in just one PES project worldwide. Some of the ecosystem services delivered by seagrass have the potential for inclusion under a PES framework but multiple challenges currently make this difficult, particularly under community-based management. PES programmes typically focus on carbon as the tradable service, but scientific uncertainties regarding seagrass carbon are likely to remain significant barriers to using carbon as the sole commodity under current carbon trading standards and market conditions. It is recommended here that project developers demonstrate the multiple ecosystem services delivered by seagrass meadows, along with their importance to coastal communities, in the planning and marketing of seagrass PES projects. Moreover, they should consider approaches that incorporate seagrass meadows into other blue carbon certified projects. The capacities of the communities that rely most heavily on seagrass are generally very limited. Consequently, demanding high levels of scientific certainty over carbon stocks and flows will exclude most of these communities. Standards, buyers and policy makers should consider building community capacity in the technical and marketing requirements of voluntary carbon standards. The voluntary carbon market has the flexibility to pioneer certified seagrass carbon, potentially leading to the inclusion of seagrass carbon in formal policy instruments, such as Nationally Determined Contributions (NDCs).

Seagrass meadows deliver multiple ecosystem services that are of particular importance to resource-poor coastal communities, yet they are rapidly declining globally. The Payments for Ecosystem Services (PES) approach has been used to fund the protection of other ‘Blue Carbon’ Ecosystems (BCE), yet seagrass has been incorporated in just one PES project worldwide. Some of the ecosystem services delivered by seagrass have the potential for inclusion under a PES framework but multiple challenges currently make this difficult, particularly under community-based management. PES programmes typically focus on carbon as the tradable service, but scientific uncertainties regarding seagrass carbon are likely to remain significant barriers to using carbon as the sole commodity under current carbon trading standards and market conditions. It is recommended here that project developers demonstrate the multiple ecosystem services delivered by seagrass meadows, along with their importance to coastal communities, in the planning and marketing of seagrass PES projects. Moreover, they should consider approaches that incorporate seagrass meadows into other blue carbon certified projects. The capacities of the communities that rely most heavily on seagrass are generally very limited. Consequently, demanding high levels of scientific certainty over carbon stocks and flows will exclude most of these communities. Standards, buyers and policy makers should consider building community capacity in the technical and marketing requirements of voluntary carbon standards. The voluntary carbon market has the flexibility to pioneer certified seagrass carbon, potentially leading to the inclusion of seagrass carbon in formal policy instruments, such as Nationally Determined Contributions (NDCs).