Comparison of the accounting approaches of the LULUCF sector in Nationally Determined Contributions (NDCs)

Since the adoption of the Paris Agreement at the COP21 in 2015, countries have been required to submit their NDCs every five years. In particular, the LULUCF sector within the NDCs plays a significant role in evaluating carbon sinks and achieving national GHG reduction targets. However, there is a lack of systematic research analyzing the methods for setting targets and contributions for the LULUCF sector within national NDCs. This study aims to analyze the differences in carbon sink targets within the LULUCF sector across national NDCs to explore the diversity of mitigation strategies. The study analyzed the NDCs and National Inventory Reports of 133 countries, categorizing the approaches into three types based on the method used to calculate greenhouse gas removals between the base year and the target year (total emissions-net emissions, net emissions-net emissions, and total emissions-total emissions). The analysis revealed that different forest-related characteristics were associated with each accounting approach. The results show that 67 countries adopted the gross-net approach, which reflects structural declines in forest carbon sinks; 30 countries used the net-net approach; and 36 countries applied the gross-gross approach. This study provides analytical evidence that differences in national circumstances and forest structures influence the methods used for NDC target setting, thereby offering a basis for future policy formulation.