So far, I haven’t talked too much about actual environmental issues. While I will have a longer piece coming out fairly soon with a lot of information on issues — climate change, biodiversity, water pollution and scarcity, and our dying oceans — I wanted to talk about blue carbon sinks.
So, let’s start simple. What is a carbon sink?
A carbon sink is something that absorbs more carbon than it releases. Once something releases more carbon than it absorbs, that becomes a carbon source.
We learned all the way back in elementary school that people and animals breathe in oxygen and breathe out carbon dioxide and plants take that carbon dioxide in. That’s what a carbon sink does. A forest is a terrestrial carbon sink because it absorbs a lot of carbon. Blue carbon sinks absorb even more.
Now what is a blue carbon sink?
So, blue carbon sinks include sea grass, mangroves, and salt marshes. They provide an important ecosystem service to humanity by helping to mitigate climate change. They sequester and store more carbon than one could imagine; however, they are being destroyed at a rate higher even than rainforests.
The following video is a very good visual representation of the basic concept behind this issue:
Why are blue carbon sinks so beneficial?
- Blue carbon accounts for 55% of carbon sequestration by carbon sinks in the world, despite taking up less than 1% of the planet’s area.
- Blue carbon sinks also sequester carbon up to 100 times faster than terrestrial forests.
- They store carbon vertically as opposed to horizontally, allowing for greater carbon storage.
- They provide green infrastructure. Some have been useful in protecting against storm surge and tsunamis.
- They limit coastal erosion.
- They provide a habitat for an abundance of different species.
- There are recreational opportunities such as snorkeling, fishing, swimming, etc.
- They offset our crazy amount of emissions!
- Also, they’re beautiful.
So what’s the problem?
Over the last century, 1,800 square kilometers of wetlands were drained, emitting two billion tons of carbon dioxide. These sinks are declining at a rate 5-10 times faster than that of rainforests, despite being significantly more effective in sequestering carbon.
Approximately 33% of the global sea grass area is gone, as is 35% of the area covered by mangroves, and 25% of the area covered by salt marshes. And the rate of decline is increasing, while our carbon emissions have reached a record high above 400 ppm.
Additionally, when carbon sinks are destroyed, they release all of the carbon that they have been storing for thousands of years. Destruction of blue carbon sinks not only takes away their valuable ecosystem service and benefits; it turns them into a carbon source.
The primary causes of this rapid decline are:
Aquaculturing. Shrimp farming is the most common type of aquaculture resulting in blue carbon sink destruction.
Coastal eutrophication. Coastal Eutrophication is the over enrichment of water with nutrients. This can result in hypoxia, a lack of oxygen in the water causing many species to die.
Urbanization. This was briefly described in the video above, but deserves a second mention. According to the UN Atlas, 44% of the population lives within 150 kilometers of the ocean. With this kind of population, commercial and residential developments pop up in coastal areas all the time.
Boats. This is mostly an effect on sea grasses. Boat propellers have been shown to tear up the ocean floor in coastal areas, taking sea grasses with them.
Just like in the case of deforestation of terrestrial forests, mangroves, sea grasses, and salt marshes can be brought back to life. We can replant and restore them. In fact, the famous REDD+ project that rebuilds terrestrial forests does the same for these coastal habitats. There is another project dedicated solely to this issue, called The Blue Carbon Project that works to conserve and restore blue carbon sinks. You can also see a list of ongoing projects on the Blue Carbon Portal.
And of course, while conservation and restoration are incredible solutions, education is the most important thing. Blue carbon depletion is a relatively unknown issue; terrestrial sinks tend to get the majority of our attention. If we can get people to “save the rainforests”, plant trees on Arbor Day, and donate millions of dollars to fuel the fight against deforestation, the same can happen here. There just needs to be more education, more dissemination of information, and more awareness. Maybe then, blue carbon sinks can make a comeback.
For more information and how you can help, visit the following sources:
Advenature 
