How Can Blue Carbon Help in the Fight Against Climate Change?

Photo by Joan Li on Unsplash

Global warming, greenhouse gases, Paris Agreement targets, carbon footprints….

Seems like a bunch of terms that are a little too common these days, eh? Okay, let’s skip the backstory of climate change and focus on the heart of today’s topic: carbon sequestration.

To put it in simple words, carbon sequestration can be understood as the process by which atmospheric carbon dioxide is captured and stored in soil, forests (check my previous blog on this), geological formations, and oceans for a long, long time. Since time immemorial, this is how nature has been working to keep atmospheric carbon at an optimum level, before the rise of the industrial revolution which started emitting excessive levels of greenhouse gases, leaving us in the mess we are in right now.

The connection between carbon sequestration and blue carbon is that, as the name suggests, the latter refers to carbon capture and storage specifically within the oceans and coastal ecosystems. Want to know how that works? Head over to the next section!

Carbon Sequestration in the Marine Environment

As explained above, carbon sequestration within the marine environment can be divided into two groups: one in the oceans and the other along the shorelines.

Photo by Jong Marshes on Unsplash

Ocean carbon sequestration can happen by means of:

1. Molecular diffusion: Being a water-soluble compound, the difference between the atmospheric and ocean pressures of carbon dioxide induces its diffusion into the water, after which it is transported into the deep ocean through the thermohaline cycle (more on this here), where it is stored for……. well, forever.
2. Absorption by marine plants for photosynthesis: Similar to their counterparts on land, plants in the ocean environment, like phytoplankton and algae, consume carbon dioxide to produce food. These plants can end up being eaten by other sea creatures for survival and growth (using carbon as building blocks) or simply sink to the bottom of the ocean upon death, where the remnants (containing carbon) may stay for centuries.

Seagrass — Photo by Benjamin L. Jones on Unsplash

Next up is coastal carbon sequestration. Compared to terrestrial forests, ecosystems along shorelines such as mangrove forests and salt marshes have the capability of sequestering ten times more carbon with higher permanence, besides naturally protecting the region from erosion. If that doesn’t sound convincing enough, take a look at the list below:

1. Mangroves: The mangrove systems are recognised as powerful carbon sinks for their ability to absorb atmospheric carbon dioxide in different parts such as roots, branches, and leaves. Unlike land forest trees that have the tendency to emit carbon back to the environment when they die, much of the carbon in mangroves settles in the surrounding soil and sediments for millennia, giving the system an advantage over ‘green carbon’.
2. Seagrass and seaweeds: Found in shallow waters closer to the coast, seagrass have the superpower to absorb carbon at a rate of 35 times faster than trees on dry land, thereby contributing significantly to the ocean’s annual carbon absorption. Seaweeds, on the other hand, are saltwater algae that can synthesise food using photosynthesis (and absorb carbon dioxide in the process). After their lifespan, both seagrass and seaweeds settle on the ocean floor in mat-like formations, sequestering carbon in the sediments.
3. Salt marshes and estuaries: Salt marshes, also known as tidal marshes or tidal wetlands, refer to the grasslands present on seashores that are constantly flooded by saltwater during high tides. Just like mangrove forests, tidal marshes are yet another significant medium for carbon sequestration, with the power to accumulate carbon at an astounding rate of 55 times faster than tropical rainforests. Remarkable, isn’t it? Likewise, estuaries, or regions where freshwater rivers meet the ocean, are sediment-rich areas that can absorb carbon ten times faster than forest sediments. This is made possible by the presence of plants like bulrushes and sedges, which trap upstream biomass debris that decays in the long run alongside the plants themselves, forming a carbon-rich layer of deposits.

Blue Carbon Credits

Blue carbon projects are among the best nature-based solutions we have when it comes to climate action, not only because of how well the system sequesters carbon but also due to the additional benefits arising from such activities. This comprises outcomes such as biodiversity conservation, prevention of coastal erosion, the creation of sustainable income sources for local communities, and the realisation of national goals in climate mitigation and adaptation (including Paris Agreement targets on reducing carbon emissions). Given how one solution results in multiple gains, it isn’t surprising to observe the exponential rise in demand for blue credits in the carbon market.

Mangroves — Photo by Maxwell Ridgeway on Unsplash

Check out the following compilation for further reading on current and upcoming blue carbon projects around the world:

a. Mikoko Pamoja — A South Kenyan project that focuses on the restoration and conservation of mangrove ecosystems through the sale of carbon credits.

b. Kelp Forest Foundation — A Netherlands-based non-profit charity organisation that aims to provide extensive knowledge and create awareness about the potential of kelp forests in carbon sequestration.

c. Seafields — The UK-based company has made an innovative plan to form a massive offshore sargassum farm that will eventually be harvested and sunken into the deep sea, sequestering the carbon absorbed throughout its lifetime permanently.

Having read the many advantages of blue carbon credits, are you now wondering what possible problems there could be with this initiative? Fret not! I have got you covered right below:

• The first point is that blue carbon initiatives can be highly expensive due to the nature of the solution itself, which focuses on remote, hard-to-reach locations and may need special facilities and equipment to execute the mission.
• The uniqueness of blue carbon projects is that the focus is always inclined towards protecting and reinstating coastal and marine ecosystems through restoration of optimum growth simulating conditions, rather than replanting trees as in the case of terrestrial forests. This makes measuring, monitoring, and keeping track of blue carbon credits even more complex.

To wrap things up…

Salt Marshes — Photo by Nils Leonhardt on Unsplash

Up to this point, we have learned how the marine environment, particularly ecosystems in the deep ocean and shorelines, sequesters carbon at much higher rates than land-based carbon solutions. We have also looked at the co-benefits arising from blue carbon projects as well as existing obstacles that can possibly hamper desired outcome of blue carbon credits in the carbon market.

Despite the identified challenges, one point remains: blue carbon projects may well be a key answer to our fight against climate change and global warming. Therefore, let us hope that with the help of appropriate policies and technologies like artificial intelligence, the limitations of the system can be addressed and the restoration of marine ecosystems can be accelerated in the near future.

Thank you for spending your time on my blog, and have a nice day.