Achieving the climate change mitigation potential of transport

Climate change is a concerned problem for scientists and policy makers all over the world. There are a lot of factors resulting in global warming， such as anthropogenic CO2 emissions including transport and household and industrialization. There are four main ways in which transport emissions can influence the climate： direct greenhouse gas emissions， CO2 mainly； indirect greenhouse gas emissions such as gases affecting the atmospheric oxidation capacity like NOX and CO and precursors of tropospheric O3； direct impact of aerosols emission， especially organic carbon （CO）， black carbon （BC） and sulphur compounds； indirect impact of aerosols， leading to clouds changes in properties and distribution. The main reason of growing emission is the increasing demand for transportation and the energy efficiency is not abundant to balance this situation.

Transportation is the most difficult part to reduce greenhouse gas emissions and energy demand. Besides， owing to the inert attribute of fossil fuels and persistent demand， it is more difficult to decarbonise in transportation part. Car use， aviation and road freight are the main emitters of greenhouse gas in the transportation part and the emission is still increasing. Road freight makes up almost 50% of the road transport total and then is the aviation. Aviation is far less environmental friendly because other greenhouse gas may be released directly into the upper atmosphere and then the effects can be only from CO2 alone.

In general， the expansion of advanced vehicle technologies plays an important role in decarbonising transport， which requires a lot like technical innovation and development. However， many of these technologies are quite expensive and perform poorly compared with current technology. A car emits less greenhouse gas and pollutants today than a car produced ten years ago. More and more cars use renewable and alternative fuels or electricity instead of fossil fuels. Aviation also benefits from technology development. The long term aim is to reduce CO2 emissions and fuel usage for aircraft.

International transport accounts for 33% of worldwide trade emissions and over 75% of the emissions comes from transport equipment， machinery， electronic equipment and manufacturing. International trade produce greenhouse gas emissions in two parts： transportation among trading partners and production of goods. In the last decade， some progress has been achieved in decarbonisation of transport sector. A number of transport studies research on climate change mitigation at regional and national scale， but only a few focus on global scale.

With the increasing greenhouse gas emissions in transport sector， policy makers are making great efforts to develop regulations to decrease emissions. The transition to a low carbon emission transport situation needs a lot of demand and policies to be developed and implemented. It is necessary to control the price and taxation of vehicles， which have an influence on use of vehicles， purchasing behaviour and overall ownership. It is also the most effective way by more complex and ambitious car purchase tax and fee policies to decelerate carbon emissions， even to decrease emissions. In order to reduce greenhouse gas emissions from road transport， the shift to public transport is necessary. Usually， a common method to increasing the public transport use is to decrease the car ownership affordability by various taxation such as fuel tax levy or parking charges at destination.

Although the greenhouse gas emissions have been controlled in some sectors like housing and industry， the transport sector is still growing. Appropriate policies need to meet the goals of sustainable development， socially and environmentally. To sum up， with the policies of taxes and regulations， technology development and demand limits， greenhouse gas emissions can be stable and behavioural change is the key factor of reducing the transport emissions.

【作者簡介】黃愛玲（1967-），女，漢族，山西太原人，中國民用航空華北地區(qū)空中交通管理局山西分局，大專，主任工程師，研究方向：民用航空氣象地面觀測技術(shù)。