Just plane wrong: Bristol Airport’s expansion application

Last October, the world was given a wake-up call. On behalf of the scientific community, the Intergovernmental Panel on Climate Change (IPCC) released Special Report 15, laying bare that we are already at 1˚C of warming and looking likely, even within the next 10–20 years, to overshoot the 1.5˚C ceiling. Beyond that, we can expect to face increasingly devastating and irreversible impacts from climate change.

The IPCC tells us we have until 2030 to cut global emissions in half, and must reach net zero globally by 2055 in order to avoid the worst impacts of climate change. It has also stated in no uncertain terms that achieving a reduction in emissions from transport, including aviation, is crucial.

Public concern about the climate emergency is increasing, and moves such as the UK Government’s “2050 Net Zero” amendment to the Climate Change Act offer some hope that we can muster a response to the challenge. I am also encouraged that North Somerset Council (NSC) has joined the ranks of authorities in declaring a climate emergency, and has pledged to reach net zero CO₂ by 2030.

Even so, my local area’s carbon footprint contains a behemoth of transport-related climate emissions. Worse still, the threat it poses to our ability to respond to climate change risks being masked.

Flight of fancy

The elephant in the room for NSC is Bristol International Airport (BIA). The airport has grown rapidly in recent years, and aims to double in size over the same time period that the IPCC warns us of runaway climate change. BIA is currently waiting on NSC to determine the first in a string of planning applications related to its growth plans.

I took a look at the CO₂ data to see what this might mean for the authority and those within it. The planning application environmental statement describes the emissions as “infinitesimal” and says they can “not be considered to have a substantial impact on UK greenhouse gas emissions….” That seemed troublingly inconsistent with a news item from 2007 which said BIA had the same carbon footprint as Malawi, at a time when the airport was only 60% as busy as today.

Looking deeper I found some very odd statistics, which I can only hope that the council is taking its time to query, and once it has done so, to challenge. First, a “future baseline” is presented in which CO₂ emissions skyrocket within the currently permitted expansion to 10m passengers per annum (50% additional emissions from 21% more passengers). But then, the “development case” for expansion from 10m to 12m passengers is presented with a far smaller magnitude of additional emissions (only 14% increase in emissions from this subsequent 20% increase in passengers).

These data are presented in the chart below in terms of ‘emissions per passenger’. Perhaps there is a story to be told to make sense of this: maybe the airport expects a short-term waning of local business travel, and an increase in flyers traveling further for holiday –  a trend which it then presciently sees reversing. Whatever the reason, and whatever the quality of the crystal ball that was used, it seems the airport is effectively claiming that all of the high carbon flights will happen regardless of the expansion, and that planning permission is needed only for additional lower emission ones. Or might this be creative accountancy designed to underplay the true impact of the airport’s expansion?

Figure 1: BIA flight CO₂ emissions per passenger – current and planned.

This apparent attempt to dupe the unwary prompted me to look further and consider what else we might not be getting properly informed about.

Flying in the face of reason

Let’s set the airport’s emissions alongside those of the council – which, according to carbon accounting convention, don’t include aviation. Central government data tells us that NSC’s ‘sphere of influence’ CO₂ emissions have fallen in recent years to 886 thousand tonnes per annum (ktpa) for 2017, but it is clear that the decarbonisation effort must intensify in order to achieve the council’s net zero pledge by 2030. BIA’s intentions, however, could make a plane wreck of the council’s efforts.

In the chart below, BIA’s emissions are layered on top of those for NSC. I have moderated the data so that future emissions per passenger are not front-loaded into the baseline, but instead averaged out across all proposed growth. Just looking at aircraft flight emissions (which are far from being the only impacts of aviation – of which, more below), NSC’s efforts to reduce local climate change emissions are cancelled out by the increase in CO₂ emissions directly from jet planes.

Figure 2: Climate change emissions from BIA’s expansion to 20m passengers. (Click on image for full resolution).

Looking further ahead, if BIA is allowed to continue to its stated aim of 20m passengers per annum by the 2040s, direct aircraft CO₂ emissions are likely to exceed 2 million tonnes per annum (mtpa) by this time, closing in on 2.4mtpa when additional non-aviation operations are taken into account.

But these initial figures only tell part of the story. Non-CO₂ gases, particulates, and contrails from aviation all affect atmospheric conditions, adding to the climate change impact. This effect, known as ‘radiative forcing’, is entirely omitted from BIA’s planning application. The precise magnitude of radiative forcing is currently uncertain, though the greenhouse gas conversion factors for company reporting produced by the Department for Business, Energy and Industrial Strategy (BEIS) clarifies that “aviation imposes other effects on the climate which are greater than that implied from simply considering its CO₂ emissions alone”. The document recommends using a multiplier of 1.9, “based on the best available scientific evidence”. I have applied this multiplier only to the high-altitude flight cruising emissions, and not to emissions related to landing and take-off – a conservative assumption, as some sources state that a multiplier of 5.2 might be justified when restricting scope in this way.

Sadly, that’s not end of the story. “Well-to-tank” emissions (documented in the BEIS 2018 spreadsheet accompanying the document linked above) which result from extraction, transport, refining and distribution of aircraft fuel add a further 21% to the direct CO₂ emissions. Additionally, lifecycle analyses indicate that manufacturing the types of aircraft operating from BIA accounts for, on average, further emissions equal to 4% of the direct flight emissions.

What goes up must come down

The planning application follows a convention where emissions are only counted for outgoing flights, with incoming flight emissions attributed to other airports. This is a convenient and simple approach used to divide up emissions between airports on a steady state, day-to-day basis. However, it looks more like a dodge when used in the context of accounting for the expansion of aviation.

Creating more flights out also creates more flights coming back. Ignoring the ‘return’ half of emissions in planning application environmental statements doesn’t make any sense. If an airport is looking to lay on 10,000 more outgoing flights and 10,000 more returning flights, then the net increase is 20,000 additional flights. Return journey emissions should be accounted for.

Figure 3: North Somerset and BIA climate emissions.

Putting the data together, I find that the all-told impact of the current planning application to 12 million passengers by 2025 is likely to be around 920ktpa CO_2e per annum, six times greater than the 154ktpa CO₂ stated in the environmental statement. Longer term, BIA’s further planned expansion entails 4.5 million tonnes more CO_2e emissions per annum than if development stopped at 10 million annual passengers.

Let’s put those figures in perspective. A tree takes 40 years to absorb one tonne of CO₂: to offset these additional emissions would require 180 million trees to be planted every year, creating 430 square miles of new forest. That would mean reforesting an area the size of North Somerset every four months. We simply don’t have three North Somersets a year to plant with trees.

Cancelling the flight

The omissions and errors in BIA’s environmental case raise serious concerns regarding whether the wool is being pulled over the eyes of the public, and local and national government alike. When we start to dig into the detail, the case for development is not at all as presented. The proposed BIA expansion does not represent an ‘infinitesimal’ increase in carbon emissions: it represents a massive source of additional emissions which would further accelerate a climate catastrophe – and completely obliterate the good work that might be done by the council in meeting its pledge to reach net zero emissions by 2030.

We are yet to see whether the council’s planning policies prioritise the climate emergency over the airport’s expansion. However, an important precedent has been set. Last month, following a 1,600 strong petition, Uttlesford Council decided to overturn its previous provisional approval and instead refuse Stansted Airport’s application to expand.  Explaining the decision, the leader of the council cited the Government’s plan to achieve net zero emissions by 2050, saying that the council now needed to look at “the bigger picture”.

This blog sets out the bigger picture for NSC. Given just how bad the environmental impact of expanding BIA would be, it is incumbent on the council to follow Uttlesford’s example and turn the application down.

Addendum, 3^rd December 2020

On 24^th November 2020, the European Union Aviation Safety Agency published an updated ‘Analysis of the non CO2 impacts of aviation’, which provides new insight into the global warming potential (GWP) of aviation. This prominent report identifies a new application of the GWP, referred to as ‘GWP*’, which produces a better global temperature response than the earlier method. It suggests that aviation emissions are currently warming the climate at approximately three times the rate of that associated with aviation CO₂ emissions alone, and therefore that focusing solely on CO₂ is inadequate.

There is urgent need for the policies used to make planning decisions to properly account for aviation’s impacts, and GWP* appears to offer a credible approach. Under The GWP* metric, the impact on global temperature from increasing Bristol International Airport’s capacity to 12 million passengers per annum is higher than stated in the article above, at around 1.36 million tonnes CO₂e per annum. This is nine times greater than the CO₂ emissions suggested by the airport’s environmental statement. The longer term expansion plans to 20 million passengers would result in an additional 6.6 million tonnes CO₂e per annum, when compared to limiting passengers at 10 million per annum.

Featured image: Tom Collins (GFDL-self), via Wikimedia Commons