Blue carbon: the hidden CO2 sink that pioneers claim could save the planet | Carbon offsetting


OOn Colombia’s Caribbean coast, rare manatee calves have been sighted in the canals and rivers of the mangrove forests of Cispatá Bay. The once critically endangered American crocodile is now seen more frequently. Birds and lizards nest in branches, fish and shrimp use the roots as nurseries. These 11,000 protected hectares (27,000 acres) of mangroves are a biodiversity hotspot.

But the Cispatá conservation project, a collaboration between the Institute for Marine and Coastal Research of Colombia (Invemar), Conservation International (CI) and Apple, is not only of interest to ornithologists and environmentalists. He caught the attention of marine scientists, researchers and businesses because he was among the first to measure and sell a new type of credit to finance conservation: “blue carbon”.

Mangroves, like other coastal wetlands, are powerful carbon sinks. That is, they suck carbon dioxide from the air to store it in their roots and branches, as well as the sediment that collects around them. They do this so well that they can store up to 10 times more carbon than forests.

And unlike tropical “green carbon” rainforests, which store carbon in biomass, and therefore release it when trees die, mangroves store most of the carbon in their soil and sediment. If it is not disturbed, it will stay there for millennia.

Cispatá conservation project location map

This superpower means that “blue carbon” (the sequestration and storage of carbon by ocean ecosystems) is gaining more and more attention in the race to net zero. And the “big three” stores of blue carbon – mangroves, salt marshes and seagrass beds – are suddenly new urgent areas for conservation.

According to the High Level Panel for a Sustainable Ocean Economy, up to a fifth of the emission reductions we need to limit the global temperature rise to 1.5 ° C will need to come from the ocean. Protecting and restoring seagrass, mangrove and salt marsh ecosystems – which account for over 50% of all carbon storage in ocean sediments – could help absorb the equivalent of 1.4 billion tonnes of emissions per year by 2050, according to the report.

These ecosystems are among the most threatened in the world by coastal development – damaged by agriculture, harmful fishing practices and pollution – so protecting and restoring them is costly.

Enter the carbon offset market. Some conservation groups sell carbon credits to fund their work. For example, Verra, a US-based nonprofit that administers the world’s leading carbon credit standard, estimates Cispatá’s mitigated carbon emissions to be nearly one million tonnes over three decades. – the equivalent of greenhouse gas emissions from the mileage of 214,000 cars.

María Claudia Diazgranados, Marine Biologist and Director of Blue Carbon at CI in Colombia, said: “We have been looking for a way to finance this ecosystem for years. About 50% of the mangroves have disappeared from the Caribbean coast over the past three decades, due to cattle ranching, roads and tourism.

The money from the sale of blue carbon credits will go directly to communities to fund the restoration of the Cispatá mangrove swamp. CI, which also works with local partners and communities, hopes that the credits will cover half of the $ 600,000 (£ 440,000) of the project’s operating costs. “The carbon market is not the goal, it’s the icing on the cake,” says Diazgranados.

A sediment corer is used to extract the soil to measure carbon and how long it has been stored there. Mangroves store most of the carbon in the soil and sediments. Photography: apple

The carbon offsetting market remains controversial. Not all diagrams are reliable. A Guardian investigation earlier this year found that several carbon programs paid for by logging companies were selling carbon credits based on maintaining forests, allowing other operations to continue.

However, for ocean scientists alarmed at the rate at which these ecosystems are disappearing, blue carbon could be used as leverage – to restore and conserve parts of the ocean that might otherwise not get much attention.

Seagrass beds, for example, which can store carbon in the seabed much faster than tropical forests – 35 times faster and storing it for millennia rather than decades – are disappearing at a rate of 7% per year, while that up to 3% of mangrove forests disappear each year. The UK alone has lost 90% of its seagrass beds over the past century.

In Cispatá, communities are involved both in ‘avoiding deforestation’, the most controversial element of the carbon offset market, and in restoration. The first step – mangrove conservation – has already paid off: CI persuaded farmers not to let their water buffalo graze and damage forests. The restoration phase will begin in a few months.

“It’s easier to prove carbon sequestration if you plant mangroves than to prove that you are avoiding deforestation if the project didn’t exist,” admits Diazgranados.

“One thing we’ve learned is that if you want to do conservation, you have to work with local communities. We have a daily presence there, a strict monitoring project, site visits and analysis of satellite images to prove that the mangrove area remains the same.

Dr Emily Pidgeon, vice president of ocean science at CI, says Cispatá has avoided the pitfalls of other carbon offset programs.

“We have learned a lot of lessons from what we have seen from the land-based projects,” said Pidgeon, insisting that the Cispatá project has strict checks and balances, including a verified methodology for calculating the benefits for emissions. carbon, communities and biodiversity. This includes regular site visits and techniques such as remote sensing.

Part of the 11,000 hectare (27,000 acre) mangrove forest in Cispatá Bay in Colombia.
Part of the 11,000 hectare mangrove forest in the Bay of Cispatá in Colombia. Restoration work has also helped rare wildlife such as manatees. Photography: apple

“About 10 years ago, we became aware of the carbon stored in coastal wetlands and how, if you restore them, carbon stocks increase,” she says. “At the time, it was considered an insane ploy. But Cispatá is the first blue carbon project to be verified by Verra and we just sold our first blue carbon credits.

CI is already in talks with the Colombian government to expand its mangrove protection efforts to three other locations.

Dan Crockett, a blue carbon specialist at the Blue Marine Foundation, an ocean conservation charity, says demand for blue carbon investment has taken off in the past year. “We have been approached by giant Norwegian shipping companies, renewable energy companies and financial firms looking for an opportunity to invest in blue carbon.

There are two reasons behind the demand, he says: “First, there is a global trend towards the need for nature-based solutions to the climate crisis. Second, there have been many advancements in our understanding of the oceans and how they sequester and store carbon. “

Blue carbon mangrove projects are in development or underway in Kenya, Senegal, Madagascar, Vietnam and in the Sunderbans in India. Each aims to reduce emissions of hundreds of thousands of tonnes of CO2 one year.

By far the largest mangrove restoration project to date – nearly 25 times the size of Cispatá – is the Indus Delta Project on Pakistan’s Arabian Sea. The Sindh regional government, in collaboration with developer Indus Delta Capital, plans to protect and restore mangroves on approximately 350,000 hectares.

Steve Crooks, of Silvestrum Climate Associates, a coastal geomorphologist who developed the methodology for the blue carbon finance program, says the Indus project aims to absorb the equivalent of 2 million tonnes of CO2 every year and sell 1 million credits in 2021, rising to 30 million credits over the next 10 years.

The blue carbon is a triple win, he says. “They are a very popular product right now, mainly for the big industry. This is a very promising time – for funding conservation, for restoring these important ecosystems, and for helping those countries that are missing important targets.


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