Some MPs will argue that it’s okay to expand Heathrow while staying within the national limit for climate change emissions. The Airports Commission did come to this conclusion, but I doubt that these MPs read the report’s smallprint about the squeeze on regional airports and a huge price hike (read more about the nonewrunways campaign).

The Airports Commission suggested two scenarios. The first is keeping to the limit of 37.5Mt, the ‘carbon capped scenario’. However much ‘technical improvements’ are assumed, plus ultimately passenger numbers need to be brought down. If you have to increase the carbon price so much that it puts people off flying then that will be across the country, not just in the south east. This means more passenger flights in London but fewer in other parts of the country, further skewing the UK’s economy to the south east. And also mainly restricting those on lower incomes.

The rise in prices is dependent upon the progress of technical improvements to make flying more carbon-efficient (if there is a big improvement in efficiency, more flights are possible within the limit), and what the underlying demand is (how many flights there would be if there was no carbon price to restrict demand).

The Airports Commission takes an optimistic view about future efficiency improvements, where assumptions are made which are not widely accepted. So what this would mean for ticket prices is not clear, but if the optimism about future technology is not correct, a family of four could have to pay an extra £435 return from Manchester to Tenerife or £363 London to Athens to keep within the limits.

As the government announced its support for a new runway at Heathrow, the Department for Transport released a technical paper which described the ‘carbon capped scenario’ (restricting aviation emissions to a level that will enable us to cut all UK carbon emissions by 80% by 2050, under the Climate Change Act) as  ‘unrealistic in future policy terms’. In other words, it can’t be done if a third runway is built at Heathrow.

The second scenario is to use carbon trading. This involves the aviation industry paying others, like home owners, or industrial producers, to cut their emissions by even more than the 80% average. There is no track record of this working well and it will become an expensive business as other sectors struggle to meet their own targets. The more it costs, the more those costs will get passed onto ticket prices.

Use this link to contact your MP  Or join this GreenPeace social media campaign to lobby those MPs who are still undecided.