摘要：Transport currently represents approximately 19% of the global energy demand and accounts for about 23% of the global carbon dioxide emissions (IEA 2009). As the demand for mobility is expected to continue to increase in the coming decades, the stabilization of atmospheric carbon dioxide levels will require the evolution of transport, along with power generation, building design and manufacturing. The continued development of these sectors will need to include changes in energy sources, energy delivery, materials, infrastructure and human behavior. Pathways to reducing carbon from the transport sector have unique challenges and opportunities that are inherent to the human choices and behavioral patterns that mold the transportation systems and the associated energy needs. Technology, government investment, and regulatory policies have a significant impact on the formulation of transportation infrastructure; however, the role of human behavior and public acceptance on the efficiency and effectiveness of transport systems should not be underestimated. Although developed, rapidly developing, and underdeveloped nations face different challenges in the establishment of transport infrastructure that can meet transport needs while achieving sustainable carbon dioxide emissions, the constraints that establish the domain of possibilities are closely related for all nations. These constraints include capital investment, fuel supplies, power systems, and human behavior. Throughout the world, there are considerable efforts directed at advancing and optimizing the financing of sustainable infrastructures, the production of low carbon fuels, and the production of advanced power systems, but the foundational work on methods to understand human preferences and behavior within the context of transport and the valuation of reductions in carbon dioxide emissions is greatly lagging behind. These methods and the associated understanding of human behavior and the willingness to pay for reduced carbon emissions are central to the design and optimization of future low carbon transport systems. Gaker et al (2011) suggest a framework, and provide insight into the willingness of transport consumers to pay for emission reductions of carbon dioxide from their personal transport choices within the context of other attributes of transport variables. The results of this study, although limited to a small demographic segment of the US population, demonstrate that people can integrate information on greenhouse gas emissions with other transport attributes including cost and time. Likewise, the research shows that the study group was willing to pay for reduction in greenhouse gas emissions associated with their transport choices. The study examined auto purchase choice, transport mode choice and transport route choice, which represent key decisions associated with transport that impact greenhouse gas emissions. Interestingly, they found that the study group was willing to pay for reductions in greenhouse gas emissions at a relatively consistent price across these transport choices. Clearly, the study results may not broadly apply to all demographics of users of transport, even in the study domain, due to the small demographic segment that was examined and the fact that the study was conducted in the laboratory. However, the methods used by Gaker et al (2011) are cause for optimism that future studies can obtain much needed mapping of transport preferences and willingness to pay for greenhouse gas emission reductions associated with personal transport choices. Although the Gaker et al (2011) study is directed at understanding the promotion of low carbon transport in the context of existing infrastructures, the ability of these studies to elucidate human behavior and preferences within the trade-offs of transport are critical to the design of future transport systems that seek to meet transport demand with constrained greenhouse gas emissions. Additional studies of this nature that examine broader demographic groups in real world conditions are greatly needed in different regions of the US and around the world. As interventions are sought to stabilize atmospheric carbon dioxide levels at levels that are expected to have limited climate impact, there is recognition that the mitigation strategies that will be implemented in the next 5–10 years will have a profound impact on the ability to constrain climate change. The evolution of the transport infrastructure over the next decade, which will provide intermodal opportunities and modal trade-offs, will be an important constraint in the ability of transport systems to reduce greenhouse gas emissions. Likewise, the evolution of the transport infrastructure over the next decade will have an equally profound impact on the ability of transport systems to meet society's expectations for transport in a cost effective and efficient manner. The ability to design and build transport infrastructures that can achieve maximum reductions in greenhouse gas emissions while satisfying the demand for transport by the society relies on the ability to understand the human behavior and human preferences for transport in the context of costs, time, time variability, safety and emission reductions. The study by Gaker et al (2011) is central to answering these questions and will hopefully serve as a conduit to motivate additional studies that examine broader segments of society in developed, rapidly developing, and underdeveloped nations to provide the human input needed to assure future transport systems that can meet greenhouse gas emission reduction targets and the transport needs of society. References Gaker D, Vautin D, Vij A and Walker J L 2011 The power and value of green in promoting sustainable transport behavior Environ. Res. Lett.6 034010 IEA 2009 Transport, Energy and CO2: Moving Toward Sustainability (Paris: International Energy Agency) (available at www.iea.org/publications/free_new_Desc.asp?PUBS_ID=2133 )
