85 per cent of Southeast Asia’s mangrove projects face permanence risks: study

Despite their huge potential as blue carbon sinks, the majority are under threat from the cultivation of palm oil, rice and aquaculture at current carbon prices, on top of cyclones and sea-level rise over the next century, researchers warn.

Thailand mangroves
Southeast Asia is home to 32 per cent of the world's mangroves, but commodities production and climate change is threatening the potential for blue carbon financing to be used to conserve them. Image: , CC BY-SA 3.0, via Flickr.

Despite Southeast Asia being home to some of the world’s largest blue carbon stocks, the vast majority of its mangrove forests face permanence risks from commodities production and climate change, a new study has found.

This threatens the integrity of blue carbon credits – generated by coastal carbon sequestration projects – as a mechanism to conserve the region’s mangroves, which can store three to five times more carbon per hectare than rainforests.

The study, led by University of Queensland researcher Valerie Kwan, found that aquaculture, followed by rice and palm oil cultivation, is likely to pose the greatest deforestation risk in the near term, with hotspots found in Indonesia, Cambodia and the Philippines.

After taking into account the risk of damage from cyclones and sea-level rise, about 85 per cent of investable mangrove forests could experience major losses over the next century, threatening 15.9 million tonnes worth of carbon dioxide sequestration potential each year, alongside coastal defence capabilities, the report said.

To date, blue carbon projects only make up a handful of the thousands of projects listed in carbon credits verifier Verra’s registry. Meanwhile, demand for blue carbon credits has surged in recent years, as seen from the oversubscribed auction of credits from the world’s largest mangrove restoration project in Pakistan, known as the Delta Blue Carbon Project, back in 2023 at US$29.72 per tonne.

Despite the price premium they appear to enjoy in the voluntary carbon market, researchers estimate that blue carbon credits can potentially only generate more revenue than commodity production for 37 per cent of investable mangrove projects in Southeast Asia. 

Even at US$200 per tonne, the pricier credits would still barely cover a third of the costs required to conserve the same amount of investable mangroves, or those that meet the additionality criterion for carbon credit certification, according to the study. 

Blue carbon insufficient to close funding gap

Given the limits to blue carbon financing, the researchers suggested that blended finance, where public and philanthropic funds are used to catalyse private investments, might be needed to close the conservation funding gap. In addition, other ecosystem services, such as coastal protection, could also be leveraged in novel funding mechanisms, the report said.

While existing standards already incorporate some degree of implementation risks, such as through buffer credits, where a proportion of carbon credits is withheld from sale and only released if project integrity is maintained over a fixed time period, the authors flagged that “some terrestrial projects are close to exhausting their buffer pools due to high frequencies of natural drivers of carbon loss”.

This could similarly be observed in mangroves in high-risk areas in the future, they noted, adding that strengthening risk mitigation efforts would be necessary for projects to generate positive conservation outcomes over the long term.

One measure the study recommended project developers to consider is the inclusion of community- and Indigenous-managed protected areas to prevent land-use conversion. 

In addition, the landward migration of mangroves in response to rising sea levels should be factored into conservation plans to build climate resilience, though the report warned that the potential for large-scale migration might be limited by the large proportion of man-made infrastructure that front a large proportion of Southeast Asia’s coastline.

While a recent review found that 47 per cent of mangroves are already included in marine protected areas – suggesting that the Kunming-Montreal Global Biodiversity Framework’s target to protect 30 per cent of the Earth’s land and ocean surfaces has been reached for mangrove areas specifically – the study said expanding protected areas could remain an effective conservation measure.

“However, the designation of marine protected area status does not necessarily negate permanence risks,” the study cautioned, adding that the decline in non-protected areas viable for commodities production could drive exploitation within conservation zones. “Moreover, natural drivers of mangrove loss, such as extreme weather events and changes to hydrology, can operate across a large spatial scale and affect mangroves regardless of protection status.”

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