評估臺灣HWP產生的CO2排放量與移除量

Abstract

全球暖化 (Global Warming) 促使生態環境急遽變遷，國際間災害頻傳，溫室氣體 (Greenhouse gas, GHG) 減排成為當前最迫切議題。森林碳匯 (Carbon sink) 是移除大氣CO2的主力，採伐木質產品 (Harvested wood products, HWP) 延續林木碳封存 (Carbon sequestration) 得以減緩碳返回大氣的時間。京都議定書 (Kyoto Protocol, KP) 將HWP貢獻納入聯合國氣候變化綱要公約 (United Nations Framework Convention on Climate Change, UNFCCC) 附件一締約方提報「 國家清冊提交 (National Inventory Submissions)」核算項目之一，台灣雖非締約方，但巴黎協定 (Paris Agreement) 賦予非締約方利益關係者 (Non-party stakeholders) 共同應對氣候議題，因此本文依據「2019年精進2006年 IPCC國家溫室氣體清冊準則 (2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories)」 (以下簡稱2019R IPCC準則) 說明精進項目，並使用儲量變化法 (Stock-change approach, SCA)、生產法 (Production approach, PA) 和大氣流動法 (Atmospheric-flow approach, AFA) 估算台灣HWP的碳儲存量 (Carbon stocks) 與其產生的CO2排放量與移除量 (Emissions and removals)。使用儲量變化法和生產法核計2021年HWP碳儲存量分別為31,078 kt C和5,894 kt C，2020年HWP產生的CO2分別為-993 kt CO2/yr和134 kt CO2/yr。使用大氣流動法核計2020年HWP產生的CO2為3,257 kt CO2/yr。同時探討時間序列起始點、回收紙納入紙和紙板 (Paper and paperboard) 類別的原料核計以及國際貿易結合不同HWP系統界限 (HWP system boundary) 等因素對估算結果的影響，並從人均消費和單位土地面積生產的觀點比較台灣與例舉國家HWP貢獻的差異。建議逆轉台灣HWP碳排放現象，並將評估結果納入「中華民國國家溫室氣體 排放清冊報告」和「國家自主貢獻 (Nationally Determined Contributions, NDCs)」等相關文件 。

Global warming has prompted rapid changes in the ecological environment, and international disasters are frequent. Greenhouse gas emission reduction has become the most urgent issue at present. Forest carbon sink is the main force to remove CO2 from the atmosphere. Harvested wood products continue the benefits of forest carbon sequestration to mitigate the return of carbon to the atmosphere. Kyoto Protocol specify that HWP contributions is incorporated into one of the accounting items in the "National Inventory Submission" submitted by Annex I Parties to the UNFCCC. Taiwan is not one of the Parties, but Paris Agreement empowers non-party stakeholders to jointly address climate issues. Therefore, this paper describes the advanced project according to “2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories”, and estimates carbon stocks and CO2 emissions and removals arising from HWP in Taiwan following the stock-change approach (SCA), production approach (PA) and atmospheric-flow approach (AFA). The carbon stocks arising from HWP in 2021 was 31,078 kt C and 5,894 kt C and the CO2 emissions and removals arising from HWP in 2020 was -993 kt CO2/yr and 134 kt CO2/yr by the stock-change approach and production approach respectively. The CO2 emissions arising from HWP in 2020 was 3,257 kt CO2/yr by atmospheric-flow approach. At the same time, the impact of factors such as the starting point of the time series, accounting of recycled paper into feedstock commodity classes of paper and paperboard, and combining with different HWP system boundaries by international trade on the estimation results are discussed. Also the difference in HWP contribution between Taiwan and the exemplified countries are compared from the viewpoints of per capita consumption and per unit land production. It is recommended to reverse the carbon emissions arising from HWP in Taiwan and incorporate the assessment results into relevant documents such as the " National Greenhouse Gas Inventory Report of the Republic of China" and "Nationally Determined Contributions".