Stephen's views on the expansion of Bristol International Airport

The airport currently has approximately 4.5 million passenger movements a year and they want to triple this number by 2030. I oppose this unsustainable growth in local air traffic. We all know that we must act with urgency to combat climate change. Aviation is currently the least taxed, lightly controlled form of transport. This situation must change and limiting any expansion of Bristol Airport will make an important contribution to a more sustainable future.

Britain has agreed to reduce its emissions of carbon dioxide, one of the main "greenhouse" gases that contribute to global warming. The government has various policies in place to reduce emissions caused by land transport, industry and our own homes. However, aviation sits outside all government targets. In fact aviation and shipping were excluded from the 1997 Kyoto Treaty that set international targets for reductions in greenhouse gases.

It should perhaps therefore be no surprise that the recent government announcement on future aviation policy actually envisages a growth in air travel over the next thirty years. The government recognises that air travel is popular and states "but if we want to continue enjoying its benefits we have to increase capacity," which means more runways, more terminals and other airport expansion plans.

We thus face a situation that if all other sectors of the economy reduce energy use over the next period, this good work will be undone by a growth in aviation emissions. I believe that this approach is complete madness.

There is also evidence that aviation emissions are more damaging than those from other sources. The production of CO2 at high altitude, together with Nitrous Oxide and associated vapour has a 'radiative forcing' effect on the atmosphere that exceeds the effect of emissions from ground level. So it is all the more important that we curb the growth of aviation.

There are various ways to control the growth of aviation. The Liberal Democrats believe that a mixture of taxation and regulatory reforms are needed. We believe that there needs to be a "green tax switch" away from taxes on income towards taxes on pollution and resource depletion. Under the current government the share of national wealth absorbed by green taxes (mainly the climate change levy and fuel duties) has actually fallen from 3.6% of GDP in 1999 to 2.9% of GDP in 2006. But aviation is the most lightly taxed mode of transport. There are no taxes on aviation fuel. The current air passenger duty offers no incentive for airlines to optimise their flight patterns.

The Liberal Democrats believe that aviation fuel should be taxed to the same extent as land travel fuel. This will require cooperation with our fellow European Union members. We would replace air passenger duty with a tax on all aeroplane flights. This plane tax would be set according to the emissions level of the plane's engines. Such a tax would incentivise airlines to fill their planes. There could be fewer flights but the same number of passengers overall. It is likely that tax changes on their own will have a marginal effect on the total number of flights but it is surely right that air travel should pay a higher rate of tax to reflect the environmental damage it causes.

Air travel can be further restricted by other market mechanisms. The landing slots at airports should be auctioned so that a true market price is set. It is ludicrous that the current landing fees are subsidised by airports such as Heathrow, which derives its revenue from retail outlets, and Bristol, which makes much of its profit from car park charges. Aviation must not be allowed to operate in the proposed cross industry emissions trading scheme, under which companies can buy up unused quotas from other low carbon use producers.

There must also be a presumption against future expansion of airports, particularly in the South East of England. It is my belief that an unsustainable expansion of Bristol Airport should also be restricted.

All taxes and restrictions must apply to air freight, as well as air passenger travel. Just over a third of all aircraft journeys are freight related.

There are of course important aerospace companies in the West Country. The industry is engaged in vital research and innovation to minimise the environmental impact. But it is my belief that lighter planes and more efficient engines should contribute to a sustainable future for the industry, rather than be an excuse for more growth.

I am fully aware that action on climate change is the biggest challenge facing my generation of politicians. Control of aviation must play a part in our sustainable future.

Please note that the authority that will determine the Airport's planning application for an increase in traffic is North Somerset Council. Neither Bristol City Council nor any of Bristol's MPs have any formal role in this process.