While carbon dioxide emissions reductions are currently at the center of global climate change discussions, the critical role of coastal-marine ecosystems for carbon sequestration or as sinks has been overlooked or even neglected. The reasons are mainly due to the lag of scientific data because of the complexity of coastal-marine ecosystems.
In Indonesia, these ecosystems have not received sufficient attention considering their importance for climate change strategy, as most of the attention has gone to terrestrial ecosystems, such as the forest and agricultural sectors.
Moreover, the Indonesian program on REDD (Reducing Emissions from Deforestation and Forest Degradation) is running slow and its forest moratorium has not worked well, making it unlikely that the Indonesian government will meet its pledge to reduce carbon emissions by 26 percent by 2020.
Tropical coastal-marine ecosystems such as mangroves and seagrass meadows are known as hot spots for biodiversity and for their valuable ecosystem services. Recently, scientists found out about the important functions of the ecosystems as carbon sequestration or sinks. This carbon, captured by coastal-marine organisms through photosynthesis, has been called blue carbon.
In this process, mangrove and seagrass binds carbon dioxide and water, and, with the assistance of sunlight, is converted into sugars and oxygen to support their growth. The remaining excess production of the plant is buried in the sediment, where it can remain stored.
Indonesia, an archipelagic country, is located along the equator at the heart of the so-called Coral Triangle. The nation’s geography causes warm climate over the country and has made the Indonesian coastal-marine environment become a suitable habitat for the growing of mangroves and seagrass.
Recently, researchers found that seagrass meadows could store up to 83,000 tons of carbon/m3/km2, mostly in the sediments beneath them. In comparison, terrestrial forests store about 30,000 tons of carbon/m3/km2, most of which is in the form of wood. This study was the first global analysis of carbon stored in seagrass and the finding was published in Nature Geoscience in May.
The study also estimates that, although seagrass meadows take up small percentage of global coastal area (about less than 0.2 percent of world’s oceans), they are responsible for more than 10 percent of all carbon buried annually in the sea.
Similar to seagrass, mangrove ecosystems have been known for their high productivity in the carbon cycle. The ecosystem can store a large amount of carbon in the deep organic sediment in which it thrives. It has the ability to store five times as much carbon as has been observed in temperate, boreal and tropical rainforests. This high amount carbon storage suggests mangroves could play an important role in climate change mitigation.
However, Indonesia’s blue-carbon ecosystems are among the world’s most threatened. About 3 to 7 percent of the ecosystems are disappearing every year, with the worst conditions found on the north coast of Java. The main reasons is mostly dredging, the degradation of water quality, deforestation and aquaculture activities.
A pilot project on Indonesian Blue Carbon in Banten Bay found at least 70 percent of the mangrove ecosystem was lost to aquaculture farms or land reclamation, while only 20 to 30 percent was used effectively by fisherman. To overcome these problems, strong attention from local communities and the government are needed.
Healthy natural coastal-marine ecosystems, such as mangrove and seagrass, provide a vast array of important co-benefits to coastal communities, particularly fishermen. These benefits include ecosystem services such as the protection of shorelines from storms, erosion or sea-level rise; the provision food from fisheries; the maintenance of water quality and landscapes for ecotourism.
In a blue carbon context these ecosystems also store and sequester a vast amount of carbon in sediments and biomass. Also from a global perspective, blue carbon mostly covers the tropical coastal-marine environment and is among the most effective carbon sinks known today.
Having the largest mangrove and seagrass ecosystems in the world makes blue carbon important for Indonesia’s climate change strategy, not only in international forums, but also to fulfill the government’s pledge to reduce carbon emissions by up to 26 percent by 2020.
The writer is principal investigator of the Indonesia Blue Carbon Project and a researcher at the Coastal and Marine Resources Research Center at the Maritime Affairs and Fisheries Ministry.