Mangroves: A Treasure Trove of Natural Assets

July 26, 2022, marks the seventh annual International Day for the Conservation of the Mangrove Ecosystem (“World Mangrove Day”) established by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Mangrove Day aims to raise awareness of the importance and conservation of mangrove ecosystems.

First, mangroves protect the life and property of people living in tropical and subtropical coastal areas by shielding them from storm surges, sea level rise, and extreme weather events. Mangroves along 100 meters of shore can reduce the intensity of tidal energy by almost 70 percent. Without mangroves, global annual flood losses would increase by USD 65 billion, and the number of people at risk of flooding would increase by 15 million annually. For climate-vulnerable countries, mangroves are a key asset. In the Philippines, for example, mangroves can reduce property damage from extreme weather events, including tropical cyclones, by 28 percent per year, saving up to USD billion. In Florida, mangroves effectively prevented USD 1.5 billion of potential flood damage from Hurricane Irma in 2017 and protected more than 500,00 lives, with a 25 percent reduction in hurricane damage in counties with mangrove distribution.

Second, mangroves provide habitats for thousands of marine organisms to breed, feed, and thrive. Eighty percent of global fish populations rely on healthy mangrove ecosystems, and in Southeast Asian countries, some economic shrimp species are entirely dependent on mangroves. Healthy mangroves increase the shrimp industry's productivity, profitability, and resilience to natural disasters. In the Gulf of California, each hectare of mangroves can generate up to USD 50,000 per year for mangrove-based blue crab and fish farming, creating an annual income of USD 19 million for the local fishing industry.

Third, mangroves provide recreational opportunities for humans. As the largest mangrove ecosystem in the Western Hemisphere, Everglades National Park in Florida generates USD 135.5 million in annual tourism revenue and supports nearly 2,000 jobs. In the six countries located in the Pacific Ocean known as the “Coral Triangle,” mangrove-based tourism revenues are expected to quadruple by 2025 (based on pre-COVID estimates) due to rising public demand for ecotourism.

Carbon stored in mangroves worldwide is equivalent to more than 21 billion tons of CO₂; if mangrove ecosystems are destroyed, this carbon will be released back into the atmosphere.

Fourth, mangroves can help mitigate climate change. Mangroves convert atmospheric CO₂ into organic carbon at almost the highest rate on earth, more than four times faster than tropical rainforests. According to studies, the carbon stored in mangroves worldwide is equivalent to more than 21 billion tons of CO₂; if mangrove ecosystems are destroyed, this carbon will be released back into the atmosphere. This means the per unit area of a mangrove ecosystem will emit more carbon than any other ecosystem, exacerbating climate change even more. Between 2000 and 2012, CO₂ emissions due to mangrove destruction may have been as high as 317 million tons, or 24 million tons per year. If the world’s 6,600 km² of highly restorable mangroves were fully restored, more than 1.3 billion tons of CO₂ could be captured, which is equivalent to the emissions from burning 3 billion barrels of oil, or more than three years of emissions from countries like Australia. The contribution of mangroves to climate change mitigation cannot be underestimated.

Mangroves play a vital role in maintaining the health of the planet. However, while mangroves, known as “coastal guardians,” are protecting the planet on which mankind depends, they are also deeply affected by climate change, overuse, invasive alien species, environmental pollution, and other threats caused by human activities.

The Global Mangrove Alliance's report on the “State of Mangrove Forests,” released ahead of World Mangrove Day 2021, shows that while there were approximately 136,000 km² of mangroves worldwide in 2016, the area of mangroves decreased by 5,807.2 km² in the 20 years prior to 2016, equivalent to about 4 percent of the 1996 mangrove area. The report also indicates that more than 60 percent of global mangrove loss since 2000 has been caused by direct or indirect impacts of human activities, mainly in Indonesia, Myanmar, Malaysia, the Philippines, Thailand, and Vietnam. Other research also highlights that from 1980 to 2000, mangroves decreased by 20 to 35 percent worldwide, with an average annual reduction of more than 1 percent, and only about 150,000 km² remained by 2000. At this rate, almost all of the world's mangroves will disappear in the next 100 years.

Fortunately, as awareness of the importance and conservation of mangrove ecosystems has increased, the potential and hope for mangrove conservation and restoration on a global scale have grown in recent years. Globally, mangroves have changed from the fastest disappearing ecosystem to the most protected: 42 percent of the world’s mangroves are now located within protected areas. 2016 data show that the area of new mangroves exceeded that of disappearing mangroves that year, although only a small proportion of the new mangrove area came from artificial restoration efforts. This is an encouraging and positive sign.

There are approximately 6,600 km² of mangroves with potential for restoration globally. One study estimates that restoring all of these mangroves will require an investment of roughly USD 11.1 billion over a twenty-year period after 2020. How to bridge this financing gap remains a challenge for the international community. Although global climate finance exceeded USD 579 billion in 2017-2018, a 25 percent increase from 2015-2016, coastal ecosystems, including mangroves, are being overlooked by global climate finance. Only USD 300 million of climate adaptation finance goes to coastal ecosystem conservation, representing 0.05 percent of total global climate finance. This is despite the clear benefits provided by healthy mangroves outlined above.

One study estimates that restoring all of these mangroves will require an investment of roughly USD 11.1 billion over a twenty-year period after 2020.

The international community is making progression and restoration opportunities in exploring and identifying innovative ways to invest in mangroves. New financial mechanisms, such as carbon markets, blue bonds, and insurance and reinsurance products, will provide additional mangrove conservation. Hybrid financing models that combine private capital with philanthropic or government grants are also being developed.

China is also actively exploring new financing mechanisms for mangrove restoration. In 2020, China began implementing a special action plan and exploring the use of market-based mechanisms to promote mangrove conservation and restoration. To this end, the Ministry of Natural Resources has introduced an incentive to grant local governments more land for new construction, equivalent to 40 percent of the area reforested with mangroves annually. According to estimates, this policy will generate billions of RMB to incentivize more private sector entities and investors to participate and invest in mangrove conservation and restoration. 

In June 2021, the mangrove reforestation project of Zhanjiang City, Guangdong Province, became the first blue carbon trading project in China, attracting private investors to participate in the conservation and restoration of mangroves. The project has become an important example of promoting China's conservation and restoration of mangrove ecosystems. On April 28, 2022, Zhanjiang city went a step further when the Zhanjiang Central Branch of the People's Bank of China, Zhanjiang Finance Bureau, and Zhanjiang Branch of Banking and Insurance Supervision jointly issued China's first document on financial support for the conservation of mangrove and marine ecological areas: "Guidance on Financial Supports for building 'city of mangroves' in Zhanjiang." The Guidance specifies financial institutions should not only actively support the conservation and restoration of mangrove ecosystems but also carry out financial innovation to help revitalize the "City of Mangroves," exploring and broadening financing channels from green credit, blue carbon development, and trading, insurance, bonds, and other aspects to meet the financial needs of building the "City of Mangroves."

It is time to consider including mangroves as a solution to the climate and biodiversity crises, setting targets for mangrove conservation and restoration in these conventions backed up by financial commitments to ensure the targets are achieved.

COP 14 of the UN Convention on Wetlands, COP 27 of the UN Framework Convention on Climate Change, and the second phase of COP 15 of the UN Convention on Biological Diversity will all be held in 2022. Due to the strong linkages to implementing these conventions, mangrove conservation and restoration should be one of the priority topics at these conferences. It is time to consider including mangroves as a solution to the climate and biodiversity crises, setting targets for mangrove conservation and restoration in these conventions backed up by financial commitments to ensure the targets are achieved.

As mangroves are finally receiving the attention they deserve, let’s look forward to the future of mangroves with confidence.

References:

Earth Security. 2020. Financing the Earth’s Assets: The Case for mangroves as a nature-based climate solution.

Spalding, Mark D. and Leal, Maricé (editors), 2021. The State of the World’s Mangroves 2021. Global Mangrove Alliance.  https://www.mangrovealliance.org/wp-content/uploads/2021/07/The-State-of-the-Worlds-Mangroves-2021-FINAL-1.pdf 

Mark Chatting, Ibrahim Al-Maslamani, etc. 2022. Future Mangrove Carbon Storage Under Climate Change and Deforestation.  https://www.frontiersin.org/articles/10.3389/fmars.2022.781876/full 

Stuart E. Hamilton and Daniel A. Friess. 2018. Global carbon stocks and potential emissions due to mangrove deforestation from 2000 to 2012. Nature Climate Change.  https://doi.org/10.1038/s41558-018-0090-4 

Daniel R. Richards, Benjamin S. Thompson and Lahiru Wijedasa. 2020. Quantifying net loss of global mangrove carbon stocks from 20 years of land cover change. Nature Communications.  https://doi.org/10.1038/s41467-020-18118-z 

段 克，刘峥延，李 刚，袁国华，邓 锋，鲁栋梁，滨海蓝碳生态系统保护与碳交易机制研究.中国国土资源经济,2021（12）:37-47