Oceans and glaciers, covering more than 70% of the Earth’s surface, play a crucial role in the planet’s health. In fact, over the past 50 years, they have absorbed more than 90% of the excess heat generated by greenhouse gases from human activities.
Water itself is one of the planet’s strongest natural allies in the cooling process, partly thanks to its ability to absorb atmospheric CO₂.
A recent study published in Global Biogeochemical Cycles provides a comprehensive estimate of how much carbon is absorbed by the oceans each year: around three gigatons, with 1/3 of that coming from human activity.
Ocean warming doesn’t just lead to sea level rise, it also increases the rate of CO₂ absorption, which in turn contributes to ocean acidification. This dangerous side effect poses a threat to many marine species and, ultimately, to human survival on Earth.
Yet among those very marine species lies a glimmer of hope for the future of aquatic flora and fauna: mollusks.
Let’s check the ones we commonly know as “shellfish”, a diverse group of soft-bodied marine animals, typically protected by a shell.
The reason why mollusks are so important is that they seem to have a natural ability to capture and neutralize excess carbon dioxide in the ocean.
Why are mollusks considered natural water purifiers?
The vital role played by mussels, clams, and oysters could significantly impact our environmental future. The Mediterranean Aquaculture Association (AMA) made this clear in an official statement addressed to Italy’s Minister for Ecological Transition, Roberto Cingolani.
Carbon dioxide is a fundamental component of life for many plants and animals, except for the kind produced by humans, which has become the driving force behind the greenhouse effect and global warming.
That’s why mollusks are now more important than ever: one ton of CO₂ stored in mollusk shells corresponds to around 3 tons of fresh mussels.
And if we consider the carbon-capturing abilities of mollusks alongside those of the world’s “green lungs”, it’s easy to appreciate how powerful this natural mechanism can be in helping to combat the environmental pollution caused by man and slow its advance.
How do mollusk shells capture carbon dioxide?
Mollusks purify the air and their shells are formed by the CO₂ in water. These protective structures are made of calcium carbonate, the literal transformation of carbon dioxide.
Carbon fixation occurs through a natural process that is fundamentally based on plant photosynthesis. It is photosynthesis that transforms more stable materials into fixed carbon which, over time, can return into circulation through decomposition and subsequent fires.
Two-thirds of the planet’s carbon is found in the aquatic mass of seas and oceans. These are the places where the most oxygen is produced, and where CO₂ becomes biomass that circulates with ocean currents.
These incredibly useful marine organisms, capable of trapping CO₂ in a stable matrix that eventually becomes sediment, have existed for over 600 million years.
The process that drives the flow of CO₂ into mollusks is very simple to explain: this species has evolved with tidal flows, managing to preserve the soft, invertebrate part of the mollusk inside their closed shells.
It is this part that filters phytoplankton from the water flow, retaining the organic component as a source of energy on one side and fixing the mineral component on the other in the form of various types of carbonates, creating a stable metal-organic matrix.
This mechanism is known as biosequestration: carbon dioxide is removed from the water and transformed into calcium carbonate, a fundamental element for building the shells of all mollusks.
An adult marine mussel can filter up to 13.000 liters of water annually, trapping CO₂ and trace elements within its shell.
This is why the role of aquaculture farms is so important: a truly natural mechanism in favor of the fight against planetary pollution.
The Blue Carbon Sink project
This project is promoted by the Associazione Mediterranea Acquacoltori, which encourages the “installation” of actual natural mollusk deposits in the sea to absorb atmospheric CO₂ and help counteract the advance of global warming caused by the greenhouse effect.
The positive effects of this process are clearly visible, for example, in mollusk farms, which eliminate nearly 20,000 tons of CO₂ from the atmosphere every year.
Thanks to the Blue Carbon Sink, since 2021 it has been possible to quantify the carbon dioxide removed through mussel farming and to generate carbon credits that can be monetized and sold.
The so-called carbon credit is “a financial unit that represents the removal of one ton of CO₂ from the atmosphere. It can be obtained through projects such as the Blue Carbon Sink, which aim to avoid, reduce, or sequester greenhouse gases. It can be purchased as a means to offset corporate emissions.”
This is according to Andrea Maggiani, founder of Carbonsink, the Italian company that develops carbon credit projects around the world. Companies can choose to support a specific project and commit to offsetting their emissions through it.
Carbonsink is particularly necessary in working toward the goal of net-zero emissions by 2050 (or halving emissions by 2030). On their own, companies are unlikely to fully eliminate their emissions. Therefore, to offset the portion they cannot eliminate, they will need to purchase carbon credits on the voluntary market.
This is not a legal obligation but, of course, companies have a strong interest in complying with the Paris Agreement, especially those that want to maintain the trust of their investors.
Let’s better understand what Carbonsink does through an example: Company X can choose to commit to financing the reforestation of a vulnerable area of the planet through one of the projects promoted by Carbonsink. From this commitment, the company will obtain carbon credits that will help it get closer to its net-zero emissions goal by 2050.
According to the certification body Gold Standard, the minimum price of a carbon credit in the voluntary market can range from €8.20/tCO₂e for energy efficiency projects to €13/tCO₂e for forestry projects.
The decarbonization process of the marine environment
For mollusks to effectively do their part, we must commit to respect our seas. First thing first: we have to keep the waters clean from fossil fuels. It is the combustion runoff and leaks of mineral oils that compromise the natural organic matrix of mollusks.
Let’s give these sea creatures the chance to work in a healthy and safe environment.
Contrary to what one might think, enabling this also means enhancing both the consumption and production of shellfish farming, which currently produces over 100.000 tons of products in Italy alone: a huge benefit for our ecosystem.
This type of economy and the projects linked to it will, over time, bring many benefits:
- Local economies will be able to grow thanks to Carbon Credits and green financing;
- The quality of air and water will only improve;
- Tourists and investors will be naturally attracted to the areas involved to “see up close” the natural resources used as tools for environmental enhancement and protection;
In short, there is no doubt: mollusks are not just delicious, they are a useful (and, today, essential) resource for the survival of our planet. By learning to farm them responsibly, we can only gain numerous benefits over time.
Fuente:
https://www.ambienteambienti.com/inquinamento-mitili-depuratori-naturali-per-acqua/
https://www.frescopesce.it/mangia-molluschi-e-proteggi-lambiente/
https://www.corriereromagna.it/i-molluschi-un-esercito-di-catturatori-naturali-di-co2/
https://ecquologia.com/cambiamenti-climatici-curare-il-mare-per-salvare-la-terra/
https://ecquologia.com/la-molluschicoltura-sequestra-la-co2/
