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pansion through taxation. Unfortunately, technological solutions are not abundant. There is some potential for the introduc- tion of alternative fuel technologies. For example, low concentration biodiesel could be introduced in the relative short- term. Liquid hydrogen is another possi- bility, although this would increase emis- sions of water vapor in the stratosphere where it also acts like a greenhouse gas. Future technological solutions will need to focus on increasing fuel efficiency through airframe and engine design and will ultimately necessitate a move from conventional turbofan aircraft to new configurations such as blended wing- body aircraf t. Although signif icantly slower, high-speed propeller aircraft are an alternative and realistic proposition and obtain a 56 percent cut in CO2
emis-
sions per passenger kilometer compared to turbofan aircraft. Therefore, with technological solu-
tions lagging behind the expansion of aviation, economic instruments provide the only viable means of tackling emis- sions. The favored approach to taxation is based on contraction and convergence, with nations working together to reduce year-on-year emissions before converging over time towards equal per capita emis- sions. Additional methods such as trading can then be used to help minimize the total cost of emission reduction activities worldwide. Key to this option would be unilateral agreement between domestic and international schemes, an approach that has so far proved to be a considerable stumbling block in implementation. The expansion of highly polluting
short-haul f lights could be tackled by encouraging a shift to cleaner modes of transportation. Many short-haul f lights could easily be replaced by rail, reducing emissions per passenger kilometer by up to 20 percent. Airfreight is the fastest grow- ing sector of aviation and limiting this to essential perishable goods could also encourage these flights to be replaced by shipping. Changes to air traffic manage- ment, such as optimizing flight routing, could also improve fuel efficiency in the region of 6–12 percent. Other economic tools include increasing the price of slots at airports, hence encouraging airlines to maximize the income from each flight.
„„ SHIPPING
Shipping is the dominant transport mode for overseas freight and is often recog- nized as a sustainable, energy efficient and relatively environmentally friendly form of transportation. It offers an alter- native mode to the forecast growth in air- freight. However, the significant levels of sulfur emitted from ships must be tack- led. One possible route is through the in- troduction of hybrid fuel cells, with ships providing the ideal platform for these technologies due to their bulk and size.
OTHER MODELS
Several existing modes of transport offer alternatives that could be promoted to achieve reductions in emissions.
„„ WALKING AND CYCLING
Finally, walking and cycling is the ulti- mate “zero carbon” and environmentally friendly solution for personal transport. However, in the developed world, this mode of transport has rapidly declined due to the growing affordability of the car. Behavioral change programs are essen- tial because reducing traffic from short journeys will not only reduce the environ- mental impact, it will also make society healthier as a whole. Measures include the promotion of “walking buses” as an al- ternative to the school run and the alloca- tion of existing road space to cycle lanes and pedestrianized areas.
„„
RAIL „„ BUSES
Buses are acknowledged as a relatively sustainable form of passenger transpor- tation, with a double-decker bus having a capacity equivalent to as much as 50 other motorized vehicles. The sustain- ability of buses will increase further with the introduction of hydrogen fuel cells and other cleaner fuel sources. More frequent services, subsidized f lat fare schemes, real-time passenger informa- tion systems, and pre-paid ticketing are all methods likely to encourage a shift to this form of transport.
A shift to rail transport is proposed as mitigation to the environmental effects of both road transport and short-haul aviation. Rail is approximately four times more efficient than road transport for pas- sengers and twice as efficient for freight. However, there is a need to ensure that strategic rail services are fully integrat- ed with other transport modes such as buses. With respect to freight, more non- bulk volume on the railways needs to be encouraged as rail is traditionally seen as a transport for bulk markets. PE
DR LEE CHAPMAN is a Roberts Research Fellow at the University of Birmingham with interests in weather, transport, and impacts of climate change on the built environment. DAVID JAROSZWESKI is a PhD student at the University of Birmingham researching the potential impacts of climate change on road freight.
Local Action Moves the World •
www.icleiusa.org
PLANET EARTH \\ DRIVING CHANGE
STEVE GIBSON; PARAG.NAIK
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