The wetlands of Cádiz reveal themselves as an important hidden sink of blue carbon, according to experts, essential to mitigate the effects of climate change
The Natural Park of the Bay of Cádiz, with 7,000 hectares of swamps, has just placed itself at the center of the world.
(Top image: Bay of Cádiz. Aerial view 2 Mr. Alejandro Asencio Guimeral)
Blue carbon sinks are so efficient they can store up to 10 times more carbon than forests
The news is that wetlands, like mangroves and other coastal wetlands, are powerful carbon sinks. Enormously powerful. That is, they absorb huge amounts of carbon dioxide from the air, that extra CO2 that keeps us on edge and ignites climate change like a torch. Blue carbon sinks store it in their roots and branches and in the sludge that accumulates around them. They are so efficient that they can store up to 10 times more carbon than forests.
Unlike tropical “green carbon” forests, which store carbon in biomass and therefore release it when trees die, plants in swamps and mangroves store most of the carbon in the soil, and if no one touches it, it remains. buried for thousands and thousands of years.
This superpower means that “blue carbon” – the sequestration and storage of carbon by aquatic ecosystems – has won places in the headlong rush to net zero. And the “big three” reserves of blue carbon – mangroves, swamps and seagrasses (like the posidonians that still survive in the Mediterranean Sea) – are suddenly areas that urgently need to be conserved to mitigate climate change, and when they are in a state of disrepair , come back to life.
We focus and in Cádiz, on the bay, there is a huge expanse of marshland, 7000 hectares, which has just become an ecological zone of great interest: it is a first-rate blue carbon sink.
If in everyone’s minds that the Amazon rainforest is the lungs of the planet, the news is that swamps, mangroves and mangroves are the hope of mitigating the effects of climate change, devouring that atmospheric CO2 that we urgently need to eliminate.
Earth tastings for CO2
“Wetlands have played an important role as carbon sinks for thousands of years.”
Miguel Ángel Mateo directs the CSIC’s Aquatic Macrophyte Ecology Group (GEMA). Since the 1990s, his group has quantified the large stocks of carbon accumulated by coastal ecosystems and, in particular, by the marine fauna of oceanic posidonia. Mateo and his team participated in the project LIFE Blue Natura. Its task has been, among others, to quantify how much CO2 the marshes of Cádiz hold and how much CO2 they embody each year. The GEMA team carried out field tests from San Juan de los Terreros to Cádiz. “With the catas we took samples of something that we could call the humus of the land, a conglomerate of roots, rhizomes, plant remains and organic material composed between 30 and 50 percent of carbon or CO2 equivalent, is the CO2 taken from the atmosphere. These swamps have played an important role as carbon sinks for thousands of years.”
The samples of this ‘humus’ that arrive at your laboratory are they cut, centimeter by centimeter, and analyze its organic carbon content. And we date it carbon 14. What for? Having the element ‘time’, because we want to know how quickly that carbon has built up. The great value of the marshes is not what they can incorporate each year, which is a little, but rather preserving what they have accumulated”, explains Miguel Ángel Mateo.
The economic value of CO2 quantification
The LIFE Blue Natura conservation project, promoted by International Union for the Conservation of Nature (IUCN), in collaboration with the CSIC, the University of Cádiz and the Junta de Andalusia, brought together scientists, researchers and a third indispensable piece in this thread to mitigate the effects of climate change that suffocate us: companies. LIFE Blue Natura is a pioneer in measuring and offering companies the possibility to finance conservation projects based on “blue carbon” in the Mediterranean. In exchange? In return, offset your extra CO2 emissions.
Specifically, LIFE Blue Natura offers companies investment in projects for the recovery of tidal marshes in the Bay of Cádiz (also for the recovery of posidonia in the Cabo de Gata-Níjar Natural Park). The advantage of the company that invests in the recovery of the swamp is that it will have CO2 credits, which will allow it to offset its surpluses.
“The objective is for companies to participate in environmental conservation and voluntarily offset their emissions through the sale of carbon credits or bonds generated by these initiatives”, explains Mar Otero, coordinator of the marine and blue economy program. at IUCN-Med.
Up to a fifth of the emissions cuts we need to limit global temperature rise to 1.5°C will have to come from the ocean, according to the High-level dashboard for a sustainable ocean economy. Protecting and restoring seagrass, mangrove and salt marsh ecosystems, which account for more than 50% of all carbon storage in ocean sediments, can help absorb the equivalent of 1.4 billion tons of emissions per year through 2050, according to the panel.
These ecosystems, including the salt flats of the Bay of Cádiz, are among the most threatened in the world by coastal development, hampered by agriculture, harmful fishing practices and pollution, so protecting and restoring them is expensive.
LIFE Blue Natura offers companies the possibility to participate in the bay recovery project and offers compensation in blue carbon credits
«Now we have a dead and dry swamp in Cádiz, if we recover its vegetation, it will represent very little what they will incorporate through photosynthesis every year. The great value is protecting what’s there. But there are two mechanisms to monetize the CO2 trapped in the swamp. One is due to the contribution of CO2 that is obtained by recovering them, or because mechanisms are established to avoid the release of carbon”, explains Miguel Ángel Mateo.
Las Aletas is an old abandoned saline solution. It is now completely dry. The proposal of the LIFE Blue Natura pilot project is to recover the flow of water that came from the ocean.
Restore the Natural Park of the Bay of Cádiz
“Of the 140 active salt pans, there are now five or six that produce salt, nothing more”
The conservation director of the Natural Park of the Bay of Cádiz, Rafael Martín, comments on what state they are in: “The marshes of the Bay of Cádiz were created by human action. It was men who created the canals to take advantage of the tides and collect the salt. The men kept the swamp channels open. In the middle of the 20th century, the salt industry was abandoned, salt ceased to be a big business with the arrival of refrigerators. Salting was no longer necessary to preserve food. So out of 140 active saline solutions, there are now five or six that produce salt, nothing more. These piped salt systems, when abandoned, dried up and became landfills. The LIFE Blue Natura recovery project for the bay aims to recover these areas, reopen the channels to allow the sea to enter with the tides, restore the flow of water maintained by men while conserving the salt flats”, explains Rafael Martín.
The carbon offset market
Nearly 1 million tonnes over three decades is the equivalent of the year’s greenhouse gas emissions from 214,000 cars
Some international conservation groups are already selling carbon credits to fund their work. For example, Will see, A US-based non-profit organization, it administers the world’s leading carbon credit standard. According to Verra, the carbon emissions mitigated by the conservation of the mangroves in Cispatá, Colombia, will allow the commercialization of one million tons of CO2 in the next ten years. If we do the math, nearly 1 million tonnes in three decades is the equivalent of the greenhouse gas emissions of 214,000 cars a year.
THE (IUCN-Med) wrote the first “Manual for designing and implementing blue carbon projects”In Europe and the Mediterranean. And it is the first to have a legal framework that gives security to companies that want to invest in the recovery of the marshes of the Bay of Cádiz in exchange for CO2 credits, under the new law on climate change of the Junta de Andalusia.
The money from companies that decide to participate will go directly to the restoration of salt pans in two areas close to each other, a dry swamp, Las Aletas, and another on the north bank of the Guadalete River, near its mouth, within the Natural Space of the Park. Natural Bahía de Cádiz which, to this day, is a quagmire full of rubbish.
LIFE Blue Nature includes in its pilot project the recovery of the marsh on the north bank of the Guadalete River, an area that could be used for the construction and operation of an underground car park.
“In the middle of the last century, the marshes of Cádiz began to dry up and to be used for other uses, until they realized that they are large stocks and deposits of CO2 that we want to keep buried. If we transform them for other uses, we run the risk that all the accumulated CO2, of billions of tons, will be returned to the atmosphere”, explains Miguel Mateo.
The carbon offset market remains controversial. Not all schemes are reliable. However, blue carbon could be used as a lever to restore and conserve parts of the ocean that would otherwise not receive much attention. The Bay of Cádiz, those 7,000 hectares of salty landscape that collect shrimp, crabs, crabs, clams and linguiri in the mud, has just gained value in the stock market. Its millennia-old work as a CO2 graveyard has just put Cádiz in the spotlight tracking high-value ecosystems in the battle to mitigate climate change. Now it is necessary to know, and that its value also reverts to the economy of its citizens, one of the main objectives of most environmental proposals that exploit blue carbon credits.
Between San Fernando and the sea, Punta del Boquerón is a tongue of dunes and swamps that jut out into the Atlantic Ocean.
