The US-China Workshop: Pathways Toward Low Carbon Cities - Quantifying Baselines and Interventions; Hong Kong; a workshop sponsored by the US National Science Foundation to bring together researchers from the USA and China to share and discuss cutting-edge research pertaining to the quantitative assessment of GHG emissions and mitigation actions at the city scale. The workshop was organized jointly by the University of Colorado, Denver (CO, USA) and the Hong Kong Polytechnic University (HKPU; Hong Kong) and was held in December 2010 on the HKPU campus. The researchers spaned multiple disciplines encompassing engineering, building sciences, architecture, urban planning, transportation, environmental sciences, atmospheric sciences and public affairs. 30 speakers attended; 13 from the USA and 17 from China. The workshop was organized broadly into three groups of topics and sessions: Integrative assessment of energy use, GHG emissions and mitigation goals in cities; Infrastructure and urban design strategies, addressing buildings, transportation and materials-waste sectors; and the Role of social actors in GHG mitigation, with emphasis on policy actors. The first finding: Quantifying GHG emissions associated with cities. The workshop concluded that looking beyond the geographic boundary at the lifecycle of infrastructures was very important in properly accounting for GHG emissions associated with cities. The participants agreed that consumption based view and expanded infrastructure based supply chain footprint for cities could be developed along with a better matrix to compare cities with each other, and that per capita matrix was insufficient. The second major finding: The participants acknowledged the challenges in linking short-lived climate forces with traditional GHG emissions in cities, and suggested more field is necessary to properly do emissions accounting in Chinese cities. This is because Black Carbon not only depends on the fuel consumed, but also the technology used because it reflects the optical properties of carbon and not the mass release of carbon per se. The third important finding: Low carbon goals in cities must be reconciled with development goals of cities, and frameworks were discussed where three types of cities were identified. Cities where Carbon mitigation was a primary objective with core benefits being things like water savings, job creating, etc. is a common model applied in US cities. In contrast, for many cities, other priorities may be important where Carbon mitigation is an ancillary goal. For cities in China, economic development would be an important aspect and the low carbon pathway would be an ancillary benefit. There was consensus that thinking about benefits and core benefits is a useful way of articulating sustainability priorities in cities. The fourth finding: Energy use in cities as a whole. Several contrasts between US and China were drawn in the various infrastructure sectors. 1. Energy use in Chinese cities is disproportionately high in the industrial sector whereas the industrial sector emission is relatively small in US cities. This reflects the amount of industrial production that China is engaged in. It also points to different strategies that may be effective in GHG emissions reduction in China vs. the US. 2. Longevity of buildings. The life span of buildings in China was much lower than the building life span that is assumed in the US and on a life cycle basis, materials choice for building materials becomes much more important in Chinese cities compared to US cities. 3. The scale and the different experiments being conducted in transportation systems. The workshop participants noted that much more research was needed to measure the efficiency of urban mixed-design and mass-transit connectivity. 4.Industrial Symbiosis. Exchange of waste materials between industries was pointed out as an extremely innovative strategy for reducing energy use in the industrial sector. Publications Anu Ramaswami, Shobhakar Dhakal, "Low-carbon policies in the USA and China: why cities play a critical role", Carbon Management, p. 359, vol. 2(4), (2011). Anu Ramaswami, James J Schauer, Xiangdong Li, Edwin Chan, "US-China Workshop on Pathways Toward Low Carbon Cities: quantifying baselines and interventions", Carbon Management, p. 377, vol. 2(4), (2011). Anu Ramaswami, Deborah Main, Meghan Bernard, Abel Chavez, Anita Davis, Gregg Thomas, Kathy Schnoor, "Planning for low-carboncommunities in US cities: a participatory process model between academic institutions, local governments and communities in Colorado", Carbon Management, p. 397, vol. 2(4), (2011). Lawrence C Bank, Benjamin P Thompson, Michael McCarthy, "Decision-making tools for evaluating the impact of materials selection on the carbon footprint of buildings", Carbon Management, p. 431, vol. 2(4), (2011). Richard C Feiock, Jungah Bae, "Politics, institutions and entrepreneurship: city decisions leading to inventoried GHG emissions", Carbon Management, p. 443, vol. 2(4), (2011). Abel Chavez, Anu Ramaswami, "Progress toward low carbon cities: approaches for transboundary GHG emissions footprinting", Carbon Management, p. 471, vol. 2(4), (2011). Mark W Davis, Christopher M Weible, "Linking social actors by linking social theories: toward improved GHG mitigation strategies", Carbon Management, p. 483, vol. 2(4), (2011).
