Blue Carbon | Environmental Defense Fund

Blue Carbon

A better tomorrow begins below

Blue carbon is the carbon stored in ocean waters, and the sediments and plants of coastal habitats.

The ocean provides a myriad of benefits to people and nature. To name a few, it provides food, protection from storms, livelihoods, biodiversity and cultural benefits. It also plays an important role in mitigating climate change and has absorbed roughly a third of all human carbon emissions since the start of the Industrial Revolution. As we negatively impact our oceans, we affect their ability to provide the benefits we have come to rely on, including their ability to trap carbon, which we focus on here. We're looking to create a better tomorrow, by tapping into and restoring these benefits now.

Ocean Habitat Benefits

Ocean habitat benefits

The ocean habitats that store blue carbon are among the best carbon absorbers on the planet, but they are also some of the most threatened ecosystems. Once they are destroyed or impaired, their stores of greenhouse gases, including carbon dioxide, can be released back to the atmosphere, accelerating global climate change.

Marine Animal Benefits

Marine animal benefits

Likewise, marine animals play critical roles in processing and storing carbon in the ocean. Overfishing, climate change, and loss of habitat have reduced the overall abundance of marine animals and altered the processes by which the ocean sequesters (traps) carbon from the atmosphere.

Nearshore

nearshore & coastal pathways

Because of climate change, overfishing, pollution and other pressures on our coastal oceans, we’ve degraded their natural ability to trap and store carbon.

Mangroves
& Seagrasses

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Mangroves And Seagrasses

Mangroves and seagrasses trap carbon from the air through photosynthesis and also by trapping sediment around their roots that contains organic carbon. Their ability to sequester carbon as well as provide important habitats for many species means it’s critical to stop destroying these tropical ecosystems and restore more of them right away.

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Marshes

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Marshes

Marshes line the edge of various bodies of water and trap carbon in sediments in coastal soils and on the ocean floor. Furthermore, these marshes can trap suspended sediments in runoff produced by human activities on land. Read More

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Seaweed

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SEAWEED

Seaweed forests and farms are capable of trapping large amounts of carbon very rapidly. One of the ways seaweeds sequester carbon is through the breakage of fronds which are carried to the deep ocean by currents. Seaweed farms sequester carbon in the same way, but perhaps not as much since they are harvested regularly for food production and other human uses. Seaweed is a valuable source of food and many other products. Some of these products and uses of seaweed sequester more atmospheric carbon than others.

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Open Ocean

open ocean pathways

Animals in the open ocean – including whales, big fish, and millions of tiny fish that live in the darker, mesopelagic waters below the ocean’s surface — can also help us lock carbon away from the atmosphere. The presence of these animals can also help make the ocean more resilient to the effects of climate change and support human livelihoods. Unfortunately, the populations of these larger animals have been dramatically reduced over the past 200 years through hunting and fishing — and new commercial fishing has been proposed to target mesopelagic fish.

Mesopelagic Fish

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mesopelagic fish

Millions of fish and invertebrate organisms live in the oceans’ mesopelagic depths – the ocean “twilight zone” found below the sunlit ocean surface layer and extending down to approximately 1000 meters. Many of these fish and other mesopelagic organisms such as zooplankton (e.g., copepods and krill) participate in a process called “diel vertical migration,” a massive, coordinated daily movement within the sea where the organisms rise up into the oceans’ surface at night to feed on phytoplankton and smaller animals, then retreat back down to mesopelagic depths during the day. Read More

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Big Fish & Whales

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Big Fish and Whales

Big fish and whales forage deep in the sea, eating smaller fish and crustaceans such as krill, storing much of the carbon these smaller species contain and then recycling the remainder of the carbon and nutrients throughout the ocean, including back near the surface where it can help drive photosynthesis that absorbs carbon dioxide from surface waters. Read More

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Blue Carbon

a better tomorrow begins below

Learn more about our oceans

Mangroves and Seagrasses

About

Mangroves and seagrasses trap carbon from the air through photosynthesis and also by trapping sediment that contains organic carbon. Their ability to sequester carbon as well as provide important habitats for many species means it’s critical to stop destroying these tropical ecosystems and restore more of them right away.

Location of habitat

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Additional benefits

Healthy tropical ecosystems also support biodiversity, recreation and tourism, fisheries production and fishing, improved water quality and protect the adjacent land from coastal erosion and climate-induced storm surge.

How to restore

how to restore

Protect these critical habitats to prevent destruction. Processes for the restoration of mangroves and seagrasses are well established and can be very effective.

Seaweed

About

Seaweed farms sequester carbon in the same way, but perhaps not as much since they are harvested regularly for food production and other human uses. Seaweed is a valuable source of food and many other products. Some of these products and uses of seaweed sequester more atmospheric carbon than others.

Location of habitat

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Additional benefits

Biodiversity, fishery enhancement, more resilient ecosystem and ocean food production systems soil additives that stimulate crop production.

How to restore

how to restore

Seaweeds could sequester more carbon and help avoid greenhouse gas emissions by:

Reversing the loss of seaweed forests by reducing pollution, restoring predators to control overgrazing, and other actions
Creating a new offshore seaweed farming industry to take advantage of the vast areas of the ocean that are suitable for seaweed farming but are not currently farmed
Setting aside a portion of the seaweed crop to be used to store carbon safely
Developing the seaweed into a feed for cattle that reduces animal methane emissions
Developing new products from seaweed such as long-lasting bioplastics that can replace plastics derived from fossil fuels
Converting seaweed into biofuels to replace fossil fuels

Emergent Marshes

About

Emergent marshes line the edge of various bodies of water and trap carbon in sediments in coastal soils and on the ocean floor. Furthermore, these marshes can trap suspended sediments in runoff produced by human activities on land.

Location of habitat

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Additional benefits

Marshes provide critical nursery habitat for many different marine species and support fisheries as well as bird and other wildlife populations.

How to restore

how to restore

Protect these critical habitats to prevent destruction. Marsh restoration methods are well established and can be very effective.

Mesopelagic Fish

About

When they retreat back into the deep ocean, they bring much of the carbon and nutrients they consumed back down with them, trapping it away from the atmosphere. Unfortunately, we know very little about these fish — even how many there are — but new evidence suggests they may together trap millions of tons of carbon each year by moving it to the deep ocean.

Location of habitat

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Additional benefits

Mesopelagic fishes in the open ocean help to sustain commercial fisheries in other parts of the ocean and serve as food for larger, more visible marine animals such as sperm whales.

How to restore

how to restore

Even though we do not fully understand the role of these mesopelagic species in trapping carbon and moving it throughout the ocean, mesopelagic organisms are already being targeted for commercial fishing. However, it is likely that reductions in mesopelagic fish communities through commercial fishing will reduce the oceans’ ability to trap carbon from the atmosphere. We can protect these species’ ability to trap carbon in the ocean by limiting or prohibiting all fishing in the mesopelagic zone, at least until we learn more about this system.

Big Fish & Whales

About

The longer these big fish and whales live, the longer they can eat and store this carbon and help cycle it throughout the oceans. Once they die, these large animals sink to the ocean floor where the carbon in their carcasses can remain trapped for a very long time.

Location of habitat

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Additional benefits

Whales and large fish help to structure the world’s marine ecosystems, allowing the oceans to continue providing critical services including the regulation of ecosystem processes such as grazing, tourism, and high value recreational fishing (which would benefit from more big fish in the ocean). If sustainably managed, large fish can also contribute to the ability of fish populations to serve as an essential source of protein for hundreds of millions of people. In many fish populations, large individuals are responsible for producing exponentially more eggs that are more viable than smaller individuals.

How to restore

how to restore

Institute management that prevents overfishing and allows for recovery of large fish. Add better area-based protection for nurseries and all areas where juveniles are present. Reduce vessel speeds in areas where whales are present and take other measures to reduce ship strikes, a leading cause of whale mortality.

Blue Carbon

A better tomorrow begins below

Ocean habitat benefits

Marine animal benefits

Nearshore

nearshore & coastal pathways

Mangroves & Seagrasses

Mangroves And Seagrasses

Marshes

Marshes

Seaweed

SEAWEED

Open Ocean

open ocean pathways

Mesopelagic Fish

mesopelagic fish

Big Fish & Whales

Big Fish and Whales

Blue Carbon

a better tomorrow begins below

About EDF

Resources

Members

Mangroves and Seagrasses

About

Location

Location

Additional benefits

how to restore

Seaweed

About

Location

Location

Additional benefits

how to restore

Emergent Marshes

About

Location

Location

Additional benefits

how to restore

Mesopelagic Fish

About

Location

Location

Additional benefits

how to restore

Big Fish & Whales

About

Location

Location

Additional benefits

how to restore

Mangroves
& Seagrasses