This strategy proposal outlines a research and development (R&D) strategy for biomass-based negative emission technologies (NETs)--one of category of NETs regarded as essential for achieving net zero emissions. More specifically, it proposes R&D focusing on: the carbon cycle/ dynamics of biomass which will serve as the underlying basic science; observation/measurement technologies, model evaluation technologies, and control technologies/methods pertaining to the carbon cycle/dynamics, with particular attention to the decomposition process of biomass where insufficient knowledge has been accumulated thus far; and technical issues and social issues which must be addressed to accelerate dissemination of the relevant technologies going forward.

In recent years, efforts to deal with climate change have become increasingly important. It is essential to not just suppress greenhouse gas (GHG) emissions, but also to employ NETs for removing CO2 in the atmosphere. It is thought that realizing carbon neutrality, even just in Japan, will require absorption/removal of at least 200 million tons of CO2 by 2050. NETs include engineering-based techniques and nature-based solutions (NbS), and among NbS, biomass-based NETs exploit the ability of biomass to absorb and store CO2 in farmland especially for the soil and forests on land, and in the oceans.

On a global basis, the amount of CO2 absorbed in the carbon cycle process of biomass, and the amount of CO2 emitted due to decomposition of biomass, are about one order of magnitude larger than CO2 emissions due to global fossil resource combustion. Therefore, if control is possible to increase absorption rate of CO2, or suppress decomposition rate of biomass, we can expect a major increase in the amount of carbon stored by biomass. However, at present, there is insufficient knowledge of the carbon cycle/dynamics due to biomass, including its decomposition, and more examination is necessary from the standpoint of basic science. Knowledge of the process of decomposition rate of biomass is especially inadequate, and there are also technical difficulties, in comparison to the absorption process by the photosynthesis that is directly linked with increased agricultural production. Therefore, from the perspective of NETs, there is a need to bolster knowledge, particularly for the underground portion on land and for the oceans, regarding the carbon cycle/dynamics.

In light of the above, we can mention--as R&D issues for accelerating practical application of NETs using biomass--elucidating the carbon cycle/dynamics, and resolving the uncertainty of predictions of the amount of absorption/fixation due to insufficient understanding of CO2 absorption/fixation mechanisms and lack of measurement data. Also control technologies and measures are needed to increase CO2 absorption/fixation volumes, while securing production of foodstuffs and lumber, etc., as we move toward practical application. For this purpose, it is crucial to not only promote R&D, but also link research organizations and organize social rules and rules, establish a system, and so forth.

In this strategy proposal, the specific R&D topics that must be addressed going forward are divided into the following three issues.

• Elucidation of the carbon cycle/dynamics attributable to biomass (Issue 1)
• Countermeasure technologies for increasing absorption and suppressing decomposition
• Evaluation of carbon market value and added value (Issue 3)

Issue 1 involves basic science and technology for elucidating the carbon cycle and dynamics attributable to biomass for farmland, forests, and oceans, respectively. Issue 2 is developing the technologies needed to accelerate practical application of biomass-based NETs. Issue 3 relates to the knowledge and governance system needed for establishing a value of carbon, i.e., "the value of removing atmospheric carbon CO2"+ "the added value specific to biomass." Knowledge found through Issue 1 and Issue 2 will be evaluated in Issue 3 in terms of costs and prices, and by applying this to things like the carbon credits market, it will be possible to proceed with studies to accelerate social implementation.

In promoting R&D, there are many elements of biomass management which extend over the long term, and thus there is a need to advance goals and related issues by dividing into time frames: short term (up to 5 years), medium term (5 to 10 years), long term (10 to 20 years), and ultra-long term (year 2050 and beyond). There is a need for funds obtained through the carbon credit market to be allocated in areas such as R&D and related implementation, and for creation of a system where research and funding can function in a virtuous cycle.

Through the promotion of R&D outlined in this strategy proposal, an R&D foundation will be established relating to these basic sciences and countermeasure technologies, and it is likely that this can be incorporated into more accurate methods of evaluation and estimation of biomass-based carbon credits. Internationally too, knowledge relating to biomass-based NETs is garnering attention, and we believe it will be possible to energize international schemes such as emissions trading and carbon taxes. These efforts are expected to not only make a tremendous contribution to global reduction of greenhouse gases, but also to contribute to achieving sustainable agriculture, forestry, and fishery industries not only in Japan but also in the world.