Combating Climate Change and Boosting Fisheries
Across Japan, initiatives are underway to utilize seaweed and seagrass for carbon dioxide (CO2) absorption and capture. These efforts aim to combat climate change while offering additional benefits like improved fisheries resources and seawater quality.
A framework for trading blue carbon credits, which represent the CO2 absorbed by oceanic ecosystems, has been established in Japan. The Japan Blue Economy (JBE) Association certifies blue carbon and issues credits, which can be traded on a trial basis.
Since fiscal 2020, the JBE Association has been evaluating seaweed restoration efforts nationwide. Certificates called J Blue Credits are issued based on the amount of CO2 absorbed through these initiatives. Operators can sell their credits to companies seeking to offset their carbon footprints, generating funds for their projects.
By fiscal 2022, a total of 26 programs were certified, resulting in the issuance of credits for 3,800 tons of CO2. These credits are reportedly traded at an average of 65,000 yen ($438) per ton this fiscal year, significantly higher than forest-linked credits.
The Mashike fisheries cooperative association in Hokkaido partnered with Nippon Steel Corp. to rebuild a local seaweed population in 2004. They used iron slag from the steelmaker's production process to supply iron to the sea, promoting the growth of konbu kelp.
In one zone, the application of iron slag led to a fivefold increase in the area of the konbu and other seaweed colonies between 2015 and 2022. Additionally, the sea urchin catch increased by up to 1.8 times, as these creatures consume konbu.
Inspired by this success, similar initiatives have been implemented in over 50 locations across Japan. Other certified programs include the transplanting of eelgrass seedlings in Yokohama Port and the development of an artificial tidal flat in Kobe for growing sea lettuce.
Another initiative in Hokkaido aims to measure blue carbon at the production areas of Hidaka Konbu and Rishiri Konbu. Seaweed farming is considered effective in reducing carbon footprints due to the plants' contribution to blue carbon through their growth.
However, there are challenges in evaluating the effects of blue carbon. No countries currently include the CO2 absorption by seaweed and seagrass in their annual greenhouse gas emissions reports to the United Nations.
The Japanese government has proposed a technique to estimate the extent of seaweed colonies nationwide using satellite images and other factors. They have also incorporated a method for calculating CO2 absorption for different types of seaweed and seagrass.
In April, Japan plans to become the first nation to present details of its carbon absorption associated with aquatic plants to the United Nations. They aim to lead the initiative in developing global criteria for blue carbon.