Advancing the Science of Climate Change (2010) / Chapter Skim
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13 Transportation
13 Transportation
Pages 333-348
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From page 333... ...
This chapter summarizes how reducing the total amount of transportation activity, shifting some of the activity to less energy- and emissions-intensive modes, increasing energy efficiency, and reducing the GHG intensity of transportation fuels could help in lowering GHG emissions from this sector. Additionally, the chapter outlines how climate change will affect the transportation sector and describes the scientific and engineering knowledge regarding adaptation options.
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From page 334... ...
In the United States between 1970 and 2007, energy intensity -- the amount of energy required to produce a unit of transport activity -- declined for nearly all transportation modes (for example, energy intensity declined by 0.3 percent per year on average for medium and heavy freight trucks, 0.8 percent per year for passenger cars, 1.5 percent per year for light trucks, 1.8 percent per year for freight rail, and 3.3 percent per year for domestic passenger air travel)
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From page 335... ...
TABLE 13.1 Energy Use and Activity Characteristics of Various Transportation Modes in 2006 Energy Use Passenger Transport Activity Goods Transport Activity Passenger -miles Trillion Ton-miles (millions) Mode BTU % Cum % % Cum % (millions)
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From page 336... ...
. The Limiting report concludes that "near-term opportunities exist to reduce GHGs from the transportation sector through increasing vehicle efficiency, supporting shifts to energy efficient modes of passenger and freight transport, and advancing low-GHG fuels." Achieving large (that is, on the order of 50 to 80 percent)
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From page 337... ...
, although it is unclear by how much." While the study concluded that significant increases in more compact, mixed-use development result in only modest short-term reductions in energy consumption and CO2 emissions, these reductions will grow over time. The implications of this and other findings for limiting GHG emissions from the transportation sector can be found in the companion report Limiting the Magnitude of Future Climate Change (NRC, 2010c)
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From page 338... ...
Shifting Transportation Modes Because there are significant differences in the energy expended per passenger-mile or ton-mile among the major modes of transportation, a second candidate strategy for reducing transportation-related GHG emissions is to shift people or freight to more energy efficient modes. The two most widely discussed options are (1)
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From page 339... ...
While high gasoline and deisel fuel taxes and road tolls tend to discourage intercity travel by private car in Europe and Japan, the ease and low out-of-pocket cost for automobile travel in the United States favors their use. Automobiles also offer flexibility for local travel once at the final destination, which is particularly important for families and leisure travelers who make trips between suburbs rather than center cities.
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From page 340... ...
. Tapping the reservoir of unrealized fuel economy potential with continued modest improvements in the efficiency of conventional gasoline and diesel engines would be the easiest way for motor vehicle manufacturers to meet these new efficiency standards.
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From page 341... ...
In addition to such federal actions, some states, led by California, have set their own fuel economy standards and taken other actions, such as requirements to sell a certain number or fraction of low-emissions vehicles. In addition to improving the efficiency of the vehicle fleet, there are behavioral changes that may be able to increase the energy efficiency of the operations of existing vehicles in the light-duty fleet, such as maintaining properly inflated tires, reducing time spent idling, and removing excess weight from trunks.
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From page 342... ...
. The report assesses some of the possible impacts of climate change on various transportation systems, with an emphasis on four categories of climate change impacts: increases in very hot days and heat waves, increases in arctic temperatures, rising sea levels, and increases in hurricane intensity.
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From page 343... ...
Transportation TABLE 13.2 Potential Climate Change Impacts on Transportation Potential Change in Climate Impact on Operations Impact on Infrastructure Thermal expansion on bridge joints and Increases in Impact on liftoff load limits at high paved surfaces very hot days altitude or hot-weather airports, Concerns regarding pavement integrity, and heat waves resulting in flight cancellations or traffic-related rutting, and migration limits on payload or both of liquid asphalt Limits on periods of construction Rail-track deformities activity due to health and safety concerns Thawing of permafrost, causing Increases Longer ocean transport season and in Arctic more ice-free ports in northern subsistence of roads, railbeds, bridge supports, pipelines, and runway temperatures regions Possible availability of a northern sea foundations route or a northwest passage Shorter season for ice roads Inundation of roads, rail lines, and airport Rising More frequent interruptions to coastal runways in coastal areas sea levels, and low-lying roadway travel rail More frequent or severe flooding of combined with service due to storm surges underground tunnels and low-lying storm surges More severe storm surges, requiring infrastructure evacuation or changes in Erosion of road base supports development patterns Reduced clearance under bridges Potential closure or restrictions at Change in harbor and port facilities to airports that lie in coastal zones, accommodate higher tides and storm affecting service to the highest surges density U.S. population centers Increase in flooding of roadways, rail Increases Increase in weather-related delays lines, runways, and subterranean in intense and traffic disruptions tunnels precipitation Increased flooding of evacuation Increase in road washout, damages events routes to railbed support structures, and Increase in airline delays due to landslides and mudslides that convective weather damage roads and tracks Increases in scouring of pipeline roadbeds and damage to pipelines Greater probability of infrastructure More intense or More frequent interruptions in air failures more frequent service Increased threat to stability of bridge hurricanes More frequent and potentially more decks extensive emergency evacuations Impacts on harbor infrastructure from More debris on roads and rail lines, wave damage and storm surges interrupting travel and shipping SOURCE: NRC (2008g)
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From page 344... ...
The report also identifies a number of research needs and potential actions that will be necessary to support climate-related decision making in the transportation sector, including improved communication processes among transportation professionals, climate scientists, and other relevant scientific disciplines; a clearinghouse for transportation-relevant information on climate change; developing climate data and decision-support tools that incorporate the needs of transportation decision makers; developing and implementing monitoring technologies for major transportation facilities; developing mechanisms for sharing best practices; reevaluation of existing and development of new design standards; and creating a federal-level interagency working group focused on adaptation. Many of these initiatives would require federal action, while others would require action by professional organizations and university researchers.
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From page 345... ...
Further research is needed on the relationships among household location, workplace location, trip-making activity, and light-duty vehicle travel, and on the effectiveness of various policy mechanisms to influence these relationships. Technological improvements such as online shopping, telecommuting, and virtual conferencing also have the potential to significantly reduce total transportation activity, but further research is needed on how to facilitate and promote expanded use of these technologies (and this research will require data on current levels of usage of these technologies -- an example of a climate-relevant observation that falls outside the rubric of traditional climate observations)
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From page 346... ...
For example, there are behavioral changes that increase the efficiency of existing vehicles, such as maintaining properly inflated tires, but we lack basic data on the prevalence of these behaviors as well as on how they might be effectively encouraged. Further research is also needed on factors that encourage the purchase of more efficient vehicles -- fuel prices are certainly one factor, but, as with the adoption of any new technology, prices are only part of the explanation and a more nuanced understanding might lead to the design of effective policies.
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From page 347... ...
Transportation projected climate changes, such as changes in temperature and precipitation, will affect different kinds of infrastructure in different regions, and improved methods of providing information to transportation decision makers. Practical research on adaptation measures, both for current transportation systems and for the design of new systems and infrastructure, is needed to better inform all kinds of transportation-related decisions as climatic conditions continue to exit the range of past experience.
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