中国湿地温室气体清单编制研究进展

湿地是重要的土地利用类型之一,在陆地生态系统碳循环中起重要作用。在缔约国向《联合国气候变化框架公约》提交的温室气体国家清单报告中,湿地作为"农业、林业及其他土地利用（AFOLU）"的一部分,因其不确定性较高而备受关注。自2006年以来,IPCC先后发布了《2006 IPCC国家温室气体清单指南》、《2013 IPCC 2006国家温室气体清单指南的增补：湿地》和《IPCC 2006年国家温室气体清单指南2019精细化》,为缔约国提供了清单编制的参考方法学。然而,IPCC指南中对湿地的定义和分类与中国现行的土地利用类型和并不统一,其提供的缺省参数对中国的研究亦未充分整合。因此,亟需在IPCC框架下开发适合中国的湿地温室气体清单方法学及参数库,以降低清单编制的不确定性。综述了IPCC湿地清单编制的方法学与中国湿地清单的研究进展,主要包括（1）比较了IPCC三部指南中的湿地清单的方法学,梳理了后两部对《2006 IPCC国家温室气体清单指南》在湿地类型、评估方法和缺省参数的更新内容;（2）比较了中国湿地清单编制与其他湿地温室气体研究结果的差异并探讨原因;（3）梳理了IPCC三部清单指南中湿地温室气体排放/清除因子数据库对来自中国的研究数据收录情况;（4）归纳了湿地的温室气体清单高层级方法学在中国的应用。在上述内容的归纳总结的基础上,基于现阶段我国在湿地温室气体清单编制方面存在活动水平数据难以获取、若干领域的排放因子缺失和评估方法不完善等问题,提出未来从提高活动水平数据透明度、加强人类活动影响评估、发展高层级方法学等方面改进。本文有助于提升我国编制湿地温室气体清单的能力,从而降低AFOLU领域对实现"碳中和"贡献的不确定性。

An overview of greenhouse gas inventory in the Chinese wetlands

Wetland represents one of the most important land use types, and plays an essential role in the terrestrial carbon cycle. Wetlands are treated as part of "Agriculture, Forestry and Other Land Use (AFOLU)" in national greenhouse gas (GHG) inventory reports submitted by parties to the United Nations Framework Convention on Climate Change (UNFCCC). The GHG budget in wetlands has received much attention from both researchers and policy makers due to the high uncertainties. The Intergovernmental Panel on Climate Change (IPCC) has issued a series of methodological documents since 2006, such as "2006 IPCC Guidelines for National Greenhouse Gas Inventories", "2013 Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories:Wetlands", and "2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories", all of which served as guidelines for national GHG inventories. Despite progresses on GHG inventory methods, the definition and classification of wetlands in IPCC guidelines are inconsistent with those in the Chinese land use classifications. Moreover, the default parameters in IPCC GHG inventory guidelines have largely not been validated against GHG data from the Chinese wetland studies. Therefore, it is imperative to establish a GHG inventory methodology and a parameter set under the IPCC framework and suitable for Chinese wetlands. This paper aims to review the state-of-the-art of GHG inventory in Chinese wetlands. Specifically, this review is intended to (1) compare the methodology of wetland GHG inventory among the three IPCC GHG inventory guidelines and summarizes the updates of the two recent guidelines to "2006 IPCC Guidelines for National Greenhouse Gas Inventories" regarding wetland classification, evaluation method, and default parameters; (2) discuss how and why GHG inventory results for the Chinese wetlands differ from GHG budget estimates based on other methods; (3) clarify how much data from Chinese wetland studies have been incorporated into the databases on emission and removal factors in the three IPCC GHG inventory guidelines; (4) summarize the state of the applications of high-level methodologies for wetland GHG inventory in China. Based on above-mentioned comparisons and summaries, this review proposes that wetland GHG inventory should be improved in terms of promoting data transparency, strengthening the assessment of human activities, and developing high-level methodologies. Such improvements are expected to meet current challenges in wetland GHG inventory, such as the unavailability of activity data and emission factors used in wetland GHG inventory, and a lack of a sophisticated evaluation methodology. This review could help enhance China''s ability to carry out wetland GHG inventory, and thereby reduce the uncertainties in the contribution of AFOLU to carbon neutrality.