國際重要組織──地方政府永續發展理事會(Local Governments for Sustainability) 與氣候變遷領導組織(C40 Climate Change Leadership Group) 均指出都市CO₂排放量盤查為落實都市地區溫室氣體減量的首要工作，並建議以IPCC 所制訂的「2006 年IPCC 國家溫室氣體清冊指南(2006 IPCC Guidelines for National Greenhouse Gas Inventories)」作為都市CO₂排放量計算之基礎。目前，我國經濟部能源局已遵照「2006 年IPCC 國家溫室氣體清冊指南」之規範，逐年進行「我國燃料燃燒CO₂排放統計」之更新，而行政院環境保護署則參採國際地方政府溫室氣體分析議定書(International Local Government Greenhouse Gas Emissions Analysis Protocol)，提出我國「縣市層級溫室氣體盤查計算指引」。然而，我國都市層級CO₂排放量計算與國家層級的計算依據不同，部門分類與計算方式亦缺乏一致性，容易造成國際接軌之落差。有鑑於CO₂排放量亦與都市土地使用配置及規劃息息相關，若僅計算都市層級的CO₂排放量，仍不足以探討都市發展過程土地使用改變對CO₂排放量之空間分佈有何影響。基於上述論點，本研究以經濟部能源局之CO₂排放量計算規則為基礎，建置一都市CO₂排放量降尺度至行政區的計算方法，同時以臺北都會區與高雄市為個案分析對象，估算其各行政區之CO₂排放量，並呈現臺北都會區與高雄市CO₂排放量的時空變化。

International institutes, such as Local Governments for Sustainability (ICLEI) and C40 Climate Change Leadership Group (C40), agree that the priority for mitigating GHGs emissions in urban areas is to inventory urban CO₂emissions, and suggest that the inventory should be done based on ＂2006 IPCC Guidelines for National Greenhouse Gas Inventories.＂ Currently, the Taiwan Bureau of Energy of Ministry of Economic Affairs follows the Guidelines to calculate national CO₂emissions every year, as reported in the ＂Statistical Analysis of Taiwan Fuel Combustion Carbon Dioxide Emissions＂. On the other hand, the Environmental Protection Administration of Executive Yuan proposes ＂Guidelines for City Level Greenhouse Gas Inventories＂ following ＂International Local Government Greenhouse Gas Emissions Analysis Protocol.＂ However, the calculations of the two levels of CO₂emissions (i.e., national and city) are based on different classifications of sectors and data sources. Additionally, urban CO₂emissions are insufficient for analyzing the relationship between land use change and spatial distribution of CO₂emissions. Accordingly, this study develops a quantitative approach for downscaling analysis on urban CO₂emissions. Using the Taipei metropolitan area and Kaohsiung City as case studies, the CO₂emissions on the city and district levels are estimated and, the temporal-spatial CO₂emissions patterns are illustrated.