American Oceans

What is Blue Carbon?

In recent years, the concept of blue carbon has gained increasing attention as a natural solution to mitigating climate change.

Scientist collecting a sediment core to asses carbon sequestration rates in the sediment of a tidal seagrass bed.

Blue carbon refers to the carbon stored in coastal and marine ecosystems, such as mangroves, salt marshes, and seagrasses.

These highly productive ecosystems are particularly important for their capacity to capture atmospheric carbon and store it within the plants and in the sediments below.

As we release more carbon dioxide into the atmosphere due to human activities, it is crucial to understand the role of blue carbon in our efforts to combat climate change.

Coastal blue carbon ecosystems not only help absorb this excess carbon dioxide, but they also provide additional benefits for wildlife, water quality, storm surge protection, and local economies.

By protecting and restoring these ecosystems, we are not only preserving crucial natural habitats but also working to reduce the impact of greenhouse gases on our environment.

What is Blue Carbon?

Blue carbon refers to the carbon captured by the world’s ocean and coastal ecosystems, which play a crucial role in mitigating the impacts of climate change.

Seagrass meadows sequester blue carbon

These ecosystems, such as mangroves, salt marshes, and seagrasses, absorb significant amounts of carbon dioxide from the atmosphere, storing it in their vegetation and soil.

There are two main types of blue carbon that we can discuss: coastal blue carbon and oceanic blue carbon.

Coastal blue carbon is stored in the vegetation and soils of mangroves, salt marshes, and seagrasses, providing crucial habitats for wildlife, improving water quality, and offering protection against storm surges.

On the other hand, oceanic blue carbon is stored in the open ocean, representing a much larger sink for carbon due to its vast size and depth. It is important to note that while coastal ecosystems cover a smaller area compared to the open ocean, they are highly effective at capturing carbon dioxide and retain it for longer periods.

Coastal blue carbon ecosystems offer a range of additional benefits apart from carbon sequestration. These benefits include:

  • Supporting a rich biodiversity of wildlife, including fish, birds, and invertebrates
  • Improving water quality by filtering pollutants and excess nutrients
  • Providing nursery habitats for commercially important fish species
  • Protecting coastlines from erosion and buffering against storm surges
  • Contributing to the livelihoods and economies of coastal communities

Given the valuable role played by blue carbon ecosystems in mitigating climate change and providing a range of ecosystem services, it is essential to prioritize their protection and restoration efforts.

Seagrass meadows

This will help ensure that these ecosystems continue to function effectively and contribute towards achieving global climate goals.

Sources of Blue Carbon

Blue carbon is the carbon that is captured and stored by ocean and coastal ecosystems.

These ecosystems play a crucial role in mitigating climate change by absorbing a significant portion of human carbon emissions. In this section, we will discuss three major sources of blue carbon – mangroves, seagrasses, and salt marshes.


Mangroves are unique ecosystems found in the intertidal zone of tropical and subtropical regions.

These forests not only store large amounts of carbon in their plant biomass but also promote sedimentation, which leads to the accumulation of carbon-rich sediments.

Mangroves can store up to four times more carbon per unit area than terrestrial forests, making them an important component of blue carbon strategies.


Seagrasses are underwater flowering plants that grow in shallow marine environments, forming meadows that act as natural carbon sinks.

A green turtle is about to feed on seagrass in shallow clear water.

These plants capture carbon dioxide from the water and use it for photosynthesis, converting it into organic matter.

Seagrass meadows can store carbon in their sediment for centuries, contributing to long-term carbon sequestration.

Additionally, they provide essential habitats for numerous marine species and help maintain water quality by filtering nutrients and pollutants.

Salt Marshes

Salt marshes are coastal wetlands found mainly in temperate regions, characterized by the presence of salt-tolerant plants.

Saltmarsh on the Virginia coast

These ecosystems capture and store large amounts of carbon in their above-ground biomass and in the sediments beneath them.

Like mangroves and seagrasses, salt marshes contribute to long-term carbon storage and provide valuable habitat for various species, including migratory birds and commercially important fish.

Benefits of Blue Carbon

Blue carbon offers a variety of benefits that contribute to the overall health of our planet. In this section, we will explore some of the key benefits of blue carbon, including climate change mitigation, biodiversity, and coastal protection.

Climate Change Mitigation

One of the most significant advantages of blue carbon ecosystems is their ability to mitigate climate change.

Coastal blue carbon ecosystems such as mangroves, salt marshes, and seagrasses serve as efficient carbon sinks. They store and process a substantial amount of carbon, reducing the amount of CO2 in the atmosphere that contributes to global warming.

Protecting and restoring these valuable ecosystems can help to reduce the negative impacts of climate change.

By preserving existing blue carbon habitats, we can prevent large amounts of carbon from being released back into the atmosphere. Furthermore, restoration efforts can increase the overall capacity of these ecosystems to absorb and store even more carbon in the future, further enhancing their climate change mitigation potential.


Blue carbon ecosystems are among the most biodiverse environments on our planet.

flamingos in one of the salt marshes.

Mangroves, seagrass meadows, and salt marshes provide essential habitats and nursery grounds for a wide array of marine species.

By protecting and restoring these ecosystems, we are also fostering richer biodiversity and promoting the health of the marine life that depends on them.

This increased biodiversity can have positive effects on various aspects of our lives, including food security, tourism, and overall ecosystem health.

The presence of diverse and abundant marine life can contribute to more productive fisheries, benefiting local economies and providing an essential source of protein for many human populations.

Coastal Protection

Blue carbon ecosystems, particularly mangroves and salt marshes, are incredibly effective at providing natural coastal protection for communities.

Mangrove Forest

They help to buffer wave energy and reduce erosion by stabilizing sediments with their dense root systems. Additionally, these habitats can contribute to the natural process of sediment accretion, which can help to counteract sea-level rise and maintain the structural integrity of coastlines.

By protecting and restoring blue carbon habitats, we can continue to reap the benefits of their valuable coastal protection capabilities.

This not only helps to safeguard the homes and livelihoods of those living in coastal communities, but also contributes to the preservation of valuable coastal infrastructure and cultural resources.

Quantifying Blue Carbon

In order to effectively quantify blue carbon, it’s important to consider both the storage capacity of various coastal ecosystems and the factors that may lead to their degradation or loss.

Sea grass on salt marsh

These ecosystems, which include mangroves, salt marshes, and seagrasses, play a vital role in capturing and storing carbon dioxide from the atmosphere.

One approach to quantifying blue carbon is by analyzing field-collected data from drone and satellite imagery.

Tools like the Blue Carbon Explorer, a Google Earth Engine app developed by The Nature Conservancy (TNC), can help identify key areas for restoration and protection by visualizing the health of these ecosystems using a combination of high-resolution satellite imagery and geographic information systems.

In addition to remote sensing, we can also quantify coastal blue carbon concentrations by examining the soil and vegetation present in these ecosystems.

By understanding the depth and distribution of carbon stored within the soil, we can estimate the amount of carbon sequestered in these habitats and monitor changes over time, such as the effects of erosion and ecosystem degradation.

When measuring blue carbon, it is crucial to consider the wider benefits that these ecosystems provide beyond carbon storage. For example:

  • Coastal ecosystems provide food and refuge for fish and marine invertebrates, supporting global fisheries.
  • They improve water quality by filtering pollutants and trapping sediment.
  • They protect coastal communities from storm surges and flooding.
  • They support local economies through tourism and ecosystem services.

By quantifying and understanding the role of blue carbon in coastal ecosystems, we can take steps to protect and restore these valuable habitats, contributing to global climate change mitigation efforts and supporting the well-being of marine life and coastal communities.

Challenges and Threats

As we explore the importance of blue carbon, we must also address the challenges and threats faced by these valuable ecosystems.

Mangrove forests that are invaded by humans

In this section, we will discuss habitat loss, pollution, and climate change impacts and their effects on blue carbon storage.

Habitat Loss

One significant challenge to blue carbon ecosystems is habitat loss. Coastal development, agriculture, aquaculture, and other human activities are causing the destruction of vital habitats such as mangroves, salt marshes, and seagrass meadows.

These losses not only decrease carbon storage capacity but also release stored carbon back into the atmosphere, exacerbating climate change.

To effectively protect and preserve blue carbon ecosystems, we must work towards sustainable land use and development practices, habitat restoration efforts, and policy interventions.


Pollution is another threat to blue carbon ecosystems. Nutrient pollution from agricultural runoff, sewage, and other sources can lead to eutrophication, causing oxygen-depleted dead zones in coastal waters.

This not only harms marine life but also reduces the effectiveness of blue carbon ecosystems to sequester and store carbon. We must work to implement better waste and water management practices and reduce nutrient pollution to protect the health of these valuable ecosystems.

Climate Change Impacts

Climate change poses additional challenges to blue carbon ecosystems, as rising sea levels, increasing temperatures, and ocean acidification can all affect their health and carbon storage potential.

For example, ocean acidification impairs the ability of seagrass meadows to absorb carbon dioxide; higher temperatures can lead to the loss of habitats due to heat stress, and rising sea levels can inundate coastal ecosystems, reducing their capacity to sequester carbon.

Tackling climate change and mitigating its effects on blue carbon ecosystems requires a concerted global effort to reduce greenhouse gas emissions and adapt our coastal management strategies to better protect these vital habitats.

Current Initiatives and Policy

Blue carbon has gained significant attention as a means of fighting climate change.

As a result, several initiatives and policies have emerged to support the protection and restoration of coastal and marine ecosystems that play a critical role in carbon sequestration. We will discuss a few of these initiatives and policies in this section.

One prominent global initiative is the Blue Carbon Initiative, which aims to mitigate climate change through the conservation and restoration of coastal ecosystems.

This initiative is a collaborative effort between the International Union for Conservation of Nature (IUCN), the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO), and Conservation International (CI).

The Blue Carbon Initiative works through research, policy development, and capacity building to enhance the understanding of the value of blue carbon ecosystems and promote their conservation.

Policies at the national and international levels have also started to recognize the importance of blue carbon. The United Nations Framework Convention on Climate Change (UNFCCC) has acknowledged the role of coastal ecosystems in climate change mitigation, and countries have started including blue carbon projects in their Nationally Determined Contributions (NDCs).

For example, countries like Indonesia and Kenya have developed action plans to protect their mangroves, recognizing their importance for carbon sequestration and adaptation to climate change.

In addition to global initiatives and national policies, non-governmental organizations (NGOs) like The Nature Conservancy have also embraced the concept of blue carbon.

The Nature Conservancy is working towards investing in blue carbon projects to increase coastal resilience and contribute to climate change mitigation.

They have projects in various countries, including the United States, Mexico, and Australia, focusing on the restoration and protection of coastal wetlands.

These current initiatives and policies are essential steps towards recognizing and leveraging the full potential of blue carbon ecosystems. By fostering collaboration and sharing knowledge, we can further our understanding and appreciation for these vital natural resources that contribute to the global fight against climate change.

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