A major challenge for cities taking action on climate change is assessing and managing the contribution of urban consumption which triggers greenhouse gas (GHG) emissions outside city boundaries. Using a novel method of creating city-level input–output tables, we present the first consistent, large-scale, and global assessment of three-scope GHG inventories for 79 members of the C40 Cities Climate Leadership Group. These inventories cover the emissions from sources located within city boundaries (Scope 1), emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam, and/or cooling (Scope 2), and all other GHG emissions that occur outside the city boundary as a result of activities taking place within the city (Scope 3). We find that, by only accounting for territorial emissions, without Scope 3, the 79 C40 cities under-report 4% of global annual GHG emissions from six key infrastructure-related transboundary sources (73%) and from service-related sectors (27%). In contrast, when only accounting for consumption-based emissions, the C40 cities would miss the mitigation target on 41% of their territorial emissions. We argue that cities should complement their GHG inventories, adding full Scope 3 to Scopes 1 and 2, and develop low-carbon consumption strategies in addition to current infrastructure-focused action on climate change.

中文翻译：

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全球城市三范围碳排放清单

城市针对气候变化采取行动的一个主要挑战是评估和管理城市消费的贡献，这会引发城市边界以外的温室气体 (GHG) 排放。我们使用一种创建城市级投入产出表的新方法，首次对 C40 城市气候领导小组的 79 个成员的三范围温室气体清单进行了一致的、大规模的全球评估。这些清单涵盖来自城市边界内源的排放（范围 1）、因使用电网供电、供热、蒸汽和/或冷却（范围 2）而产生的排放，以及所有其他发生的温室气体排放由于在城市内发生的活动而在城市边界之外（范围 3）。我们发现，仅考虑地域排放，而不考虑范围 3，79 个 C40 城市少报了 4% 的全球年度温室气体排放量，这些排放量来自六个关键基础设施相关跨界来源 (73%) 和服务相关部门 (27%)。相比之下，如果仅考虑基于消费的排放，C40 城市将无法实现其 41% 的区域排放的减排目标。我们认为，城市应补充其温室气体清单，将完整的范围 3 添加到范围 1 和范围 2，并在当前以基础设施为重点的气候变化行动之外制定低碳消费战略。