Tsung-Chen Lee, Chia-TSung Yeh, & Chen-Yu Chan, National Taipei University, Taipei, Taiwan

Shin-Kun Peng, Academia Sinica, Taipei, Taiwan

Presentation Title: Bottom-up urban CO2 emissions: A consistency check with top-down national estimates




Although climate change has been recognized as a global externality, climate responses are, in fact, multi-spatial. In this regard, the roles and responsibilities of cities in CO2 mitigation have drawn increasing attention in the recent years. To facilitate the optimal design of effective mitigation policies at city levels, it is essential for city authorities to understand the magnitudes and sources of their CO2 emissions. At present, however, the widely accepted principles of estimating CO2 emissions, such as IPCC guidelines are, in general, at the national level. Despite several academic papers, international or national protocols, and local government guidelines suggesting the methods of estimating CO2 emissions at the city level, few justify the robustness of their estimates. In addition, there is a lack of cross-cities comparison and consistency check with national top-down estimates. To bridge this gap, this research has constructed a comprehensive "bottom-up" framework for estimating urban CO2 emissions, offering a consistency check with "top-down" national estimates. 

Policy/Practice Implication of Research

Using Taiwan as a case study, the geographic distribution of CO2 emissions within the country are displayed. This 'CO2 emissions map' provides important information on the coordination of climate policies at top-down national levels and bottom-up urban or regional levels.

Market-based measures (MBMs) of carbon mitigation (i.e., carbon taxes and emissions trading schemes) serve as cost-effective policy instruments, which are of considerable attention, but most of the associated economic impact analyses to date are performed at national, multi-country or global levels. These studies may belie the extreme economic impacts on individual cities or regions because they provide only the averages at higher spatial levels. The “CO2 emissions map” could serve as a supplement for better understanding the impacts of MBMs at lower spatial levels. With this information, any urban- or regionally-coordinated set of measures to alleviate the burden of MBMs could be more effectively targeted if the most adversely affected sectors within the city or region are identified.

Knowledge Gaps and Needs

In order to implement carbon mitigation policies effectively, needed is:

  • A thorough analysis of the sources and drivers of GHG emissions at different spatial and temporal scales;
  • A full understanding about the mitigation potentials, consisting of mitigation sectors and their actions; and,
  • A city- or regional-wide impact analysis of MBMs.