How Japan is harnessing blue carbon as a pathway to net zero 

In April, over 100 volunteers gathered in the bay area of Yokohama, the second-largest city in Japan after Tokyo, to plant eelgrass on the seabed, following Japan’s aim to achieve carbon neutrality by 2050. The event is part of the Yokohama Blue Carbon Project, launched in 2011, and is the first initiative of its kind in Japan to promote global warming countermeasures using marine resources.

Under the Fukuoka City Hakata Bay Blue Carbon Offset Programme, the city in southern Japan converts the carbon dioxide (CO2) absorbed and fixed by eelgrass and other seaweed beds in Hakata Bay into credits. These credits, known as “Hakata Bay Blue Carbon Credits,” are sold.

By purchasing “Hakata Bay Blue Carbon Credits,” individuals and companies can offset the CO2 emissions they cannot otherwise reduce in their daily lives and business operations. The proceeds from these sales support the efforts by “Hakata Bay NEXT Conference” to create eelgrass beds and engage in other environmental conservation activities.

The term “blue carbon” was introduced in a report by the United Nations Environment Programme (UNEP) in October 2009. It highlighted the carbon stored in marine environments, such as seaweed beds, shallow waters, seagrass beds, wetlands, tidal flats and mangrove forests, as a new way to capture carbon. These ecosystems, referred to as “blue carbon ecosystems,” play a crucial role in isolating and storing CO2.

According to the report to the UN on the state of Japan’s greenhouse gas emissions, they totalled approximately 1,085 million tons (CO2 equivalent). This level represents a decrease of 2.3% (approximately 25.1 million tons) from 2021 levels and a decrease of 22.9% (approximately 322.1 million tons) from those in 2013. It was the lowest recorded value, continuing a steady downward trend towards net zero by 2050.

The report also showed that for the first time globally, the absorption capacity of one of the blue carbon ecosystems, seagrass and seaweed beds, was approximately 350,000 tons. This report, a collaboration between the Ministry of Land, Infrastructure, Transport and Tourism (providing area data) and the Ministry of Agriculture, Forestry and Fisheries (providing absorption coefficient data for different seaweed bed types), expands on previous calculations for mangrove forests. Calculations for salt marshes and tidal flats are also on the agenda.

Interest and efforts toward blue carbon in Japan are accelerating. In 2021, Blue Carbon.jp was launched by Junko Edahiro in Shizuoka, a prefecture she chose to relocate to.

“I’ve been involved in environmental work for around 25 years and I strongly believe that two crucial issues we need to address are combating global warming and restoring the health of our oceans. One initiative that addresses both of these concerns is blue carbon”, says Edahiro. “I aim to enhance Japan’s efforts in seaweed bed restoration and blue carbon initiatives by promoting environmental education for the next generation”, she adds.

Public-Private-Partnership collaboration is also blossoming. At the end of 2023, energy company ENEOS announced an initiative to explore a large-scale creation of blue carbon through cooperation with government and academic institutions. ENEOS partners with the Port and Airport Research Institute, the Japan Agency for Marine-Earth Science and Technology, the National Institute of Advanced Industrial Science and Technology, and the University of Tokyo.

The initiative aims to generate over 1 million tons of blue carbon on a significant scale. Through this collaboration, industry, government and academia will leverage their expertise to study the “utilization of blue carbon ecosystems as carbon dioxide sinks”.

The efforts are not without challenges. Gregory Nishihara, Professor of Marine Algal Ecology at Nagasaki University says that based on his calculation, if we wanted to capture all emissions just using seaweeds, we need to use 10% of Japan’s maritime exclusive economic zone, which is approximately 433 million hectares.

Also, according to the Environment Ministry data, Japan’s seagrass and seaweed beds have shrunk, making reforesting the sea floor even more challenging. They are now only estimated to cover less than 200,000 hectares, or around half a million acres, down from a little over 850,000 acres over three decades.

Taking steps forward can only innovate new approaches, especially when over half the world’s gross domestic product is moderately or highly dependent on nature, as stated in the World Economic Forum’s New Nature Economy - Nature Risk Rising, World Economic Forum 2020.

The Forum also hosts the Blue Carbon Action Partnership to accelerate the development of blue carbon projects in partnership with countries (currently Indonesia and Philippines) and to strengthen the science, investments and benefits to communities.

As Michio Kondoh, Professor at Tohoku University Graduate School, comments, “We are entering an era in which loans can be obtained through proper management of natural capital. By making good use of the nature that local communities have at their disposal, they can also improve the flow of the economy.”