How can we combat global warming? Planting trees is a good place to start. Forests are the lungs of our planet. They produce oxygen and absorb the emissions we produce, while also keeping potentially harmful carbon in the ground, where it belongs. 

But when you think of forests, you probably don’t think of coastal and marine ecosystems, right? And yet, these ecosystems store more carbon than anywhere else on Earth. Carbon absorbed and stored here is called “blue carbon”. And blue carbon could be the key to a greener future.  

What is blue carbon and why is it important? 

Blue carbon is the carbon stored in coastal and marine ecosystems. Most of it is carbon dioxide (CO2) that has dissolved directly into the ocean. Lots of blue carbon is stored in underwater sediment, coastal vegetation, and coastal soils. 

Coastal ecosystems can be sea grasses, mangroves, and salt marshes. They all play a crucial role in capturing and retaining carbon. It is for this reason that they’re sometimes called ‘carbon sinks. Although coastal ecosystems are smaller than terrestrial forests, they actually  sequester and store more carbon. 

Unlike in tropical forests, where carbon is stored in above-ground plants, blue carbon is stored below the ground., Some blue carbon can be thousands of years old.  

Did you know? Coastal ecosystems store more carbon per hectare than terrestrial forests. 

Coastal ecosystems: Our first line of defense 

Every year, mangroves and coastal wetlands suck ten times more carbon out of the atmosphere than tropical forests. They also store three to five times more carbon.  

When these habitats are damaged or destroyed, all that carbon is released into the atmosphere as harmful greenhouse gases. This makes protecting and restoring coastal habitats essential to combating climate change.  

Healthy coastal ecosystems give us loads of other benefits besides carbon. They offer protection from storms and erosion, provide nurseries for commercial fisheries, and are beautiful places for us to explore and enjoy. 

Did you know? Coastal habitats make up less than 2% of total ocean area, but store around 50% of the carbon sequestered in ocean sediments 

Coastal ecosystems in Indonesia 

In case you didn’t know, Indonesia is huge. This enormous archipelago is home to nearly a quarter of the world’s mangroves, which cover about 3.2 million hectares.

Together with 3 million hectares of sea grasses, these areas store about 3.4 billion metric tons of carbon – that’s 17% of all the blue carbon in the world. 

But despite their massive importance, Indonesian mangroves are under serious threat. Every year, more of these areas are converted into ponds or swallowed up by urban expansion. 

Indonesia emits 190 million tons of CO2-eq every year. That’s 42% of the world’s annual emissions from the destruction of coastal ecosystem services. 

Read more: Five types of mangrove in Indonesia and their benefits 

Trees4Trees mangrove restoration program  

As part of our commitment to support the Indonesian government’s efforts to restore mangrove cover and preserve blue carbon stored in coastal ecosystems, Trees4Trees has been busy replanting mangroves in Central Java. 

“From 2021 to 2022, we successfully planted more than 100,000 seedlings in seven coastal villages in Pati,” explains Khoirum Minan, Trees4Trees Pati Unit Manager. “We aim to prevent tidal surges that can erode shorelines and pose a threat to residential areas and fishponds owned by local communities,” he added

The benefits of Trees4Trees’ mangrove planting mission in Central Java can already be clearly seen. “Mangroves we planted in 2021 have formed a green belt,” says Mustofa, the farmer group leader in Dukuhseti village in Pati. “The ecosystem has taken shape, and we often observe birds, fish, and crustaceans in these newly restored mangrove areas.”  

Did you know? It’s estimated that 83% of the global carbon cycle is circulated through the ocean. 

Elsewhere in Central Java, Trees4Trees recently planted 7,600 plants in an area of mangroves spanning 2.4 –hectares in Segara Anakan, Cilacap., This previously degraded mangrove ecosystem is now thriving.  

This small-scale pilot project was a chance for us to try out our planting methods before the time came to tackle a bigger challenge. And that time has now arrived.  By 2027, Trees4Trees aims to plant 3.5 million trees in an area covering 1,000 ha in Cilacap, Central Java. 

Read more: Replanting mangroves rebuilding future in Central Java 

“Our project aims to restore the degraded mangrove ecosystems, enhance mangrove species diversity, promote fish populations and biodiversity, and eliminate invasive weeds that disrupt the mangrove growth,.” says Armin Mubarok, the Trees4Trees Impact Officer leading the mangrove planting program in Cilacap. 

Through our mangrove planting efforts, Trees4Trees is working to restore degraded mangrove ecosystems and build new green belts along Indonesia’s precious coastlines.  

Together with our local partners, we’re working to preserve blue carbon, and provide lasting benefits to people and nature.  

Writer: V. Arnila Wulandani. Editor: Christopher Alexander