Bristol Airport Expansion – Why the Carbon Case Doesn’t Add Up

The owners of Bristol Airport have recently submitted an application to expand the airport’s capacity from 10 million mppa (passenger movements per annum) to 12 mppa, as part of a longer-term plan to double the airport’s capacity by 2040. They have clearly been shaken by the scale of public opposition to these proposals, and have been trying to argue that their plans are consistent with the UK’s carbon reduction obligations. This post explains why those claims are misleading.

Since 2009 the Climate Change Committee has worked on the assumption that UK international aviation emissions will be no higher in 2050 than they were in 2005. This target does not come from any expert advice; it was a political compromise thrashed out in the cabinet of the last Labour government in 2009, as explained in this article. It is extremely generous to the aviation industry, compared to other sectors of the economy, as the advisory panel to the CCC has pointed out (page 12 of this report). The target itself remains unchanged for reasons of political inertia.

The official figures on UK aviation emissions are substantial underestimates as explained here. The rest of this blog will leave that problem aside and take the official figures at face value. Aviation emissions in 2005 were 37.5 MtCO2e; passenger movements were 230 mppa. Until recently, the CCC assumed that passenger demand could increase by 60%, whilst keeping emissions down to that level. In their recent Net Zero report, they propose a new lower target of 31 MtCO2e, still assuming that demand can increase by 60%. They promise a new report explaining how this could be done, through a combination of efficiencies, technological improvements and some use of biofuels. All of this is rather speculative.

The DfT’s 2017 aviation forecasts, show two main scenarios: “constrained” and “unconstrained”. The central “unconstrained” forecast (page 90) is for 490 mppa. That would be +115% compared to 2005. Even the “capacity constrained” forecast (page 96) shows 410 mppa – that is +78% compared to 2005. That “constrained forecast” specifically includes an assumption that Bristol Airport will remain at 10 mppa (page 86).

So we have a situation where even keeping Bristol’s flights down to current levels would bust the UK’s carbon budgets. Increasing that capacity – unless it was offset by closing down airports or runways somewhere else – is clearly incompatible with the UK’s legal obligations under the Climate Change Act (2008).


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