Heathrow Airport
Image credit: Creative Commons, tataquax

Last Friday, Green MP Caroline Lucas and Airbus Senior UK VP Katherine Bennett got into a tad of a statistical snafu on Any Questions. Katherine had stated that Aviation accounted for ‘2-3% of man made CO2’, Caroline rebutted saying that wasn’t the full story, which it isn’t as EASA states here:

The main pollutants emitted by aircraft engines in operations are carbon dioxide (CO2), nitrogen oxides (NOx), sulphur oxides (SOx), unburnt hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM) and soot.’.

Caroline came back, saying:

It’s not true to say that Aviation is only responsible for 1 or 2% of our overall Greenhouse gas emissions, when you look at condensation trails, when you look at the impact of those kinds of emissions at altitude, when you look at the Nitrogen as well, we’re looking at something that’s knocking much more closely to 8 or 9%’

So who’s right?

Let’s start with CO2, the Donald Trump of gases – awful and constantly grabbing the headlines. According to ATAG, a not-for-profit representing ‘all sectors of the aviation industry’, IATA, the body representing 290 airlines globally and the European Commission, globally the aviation industry is responsible for 2% of all man made CO2 emissions. According to EASA, the Agency responsible for aviation inside the EU, the sector is responsible for 3.6% of CO2 emissions for the EU 28. For the UK, now that DECC is long gone, it’s to BEIS that we go to trawl for the latest stats, and here’s where it gets tricky.

For the UK, Aviation is split in emissions statistics, into Civil, and ‘Emissions arising from use of fuels from UK Based International Aviation Bunkers’ which, according to the footnotes ‘do not count towards the UK greenhouse gas emissions totals as reported to the UNFCCC and the European Commission, or used for assessing progress against UK emissions reduction targets.’

Oh joy…

Civil Aviation accounted for an estimated 1.5 MtCO2e in 2017, or 0.4% of total UK carbon emissions. Which is child’s play compared to ‘passenger cars’ 69.1 MtCO2e or 18.5% of total UK CO2 emissions. But don’t planes fly outside the UK? Yes, how else would we colonise the west of Spain without those flights to Malaga and Alicante.

Now we come to that pesky International Aviation, because really, who cares about planes if they don’t go anywhere Brexit isn’t? These emissions statistics are calculated based upon the refuelling of planes in the UK at airports, but BEIS say:

Whether emissions from refuelling at UK-based international aviation and shipping bunkers can be used as an accurate estimate of UK international aviation and shipping emissions depends on what assumptions are being made about how to allocate international aviation and shipping emissions to different countries.

Basically, the fuel’s here, sold here, and burnt here on take off and partially at cruise, but because it’s a plane and planes travel outside our borders, because that’s what International Aviation means, we don’t take any responsibility for it.

So for 2017, fuels from Aviation Bunkers in the UK produced an estimated 34.6 MtCO2e, half as much produced by passenger cars but nonetheless a massive amount. If you add the emissions by International Aviation from UK fuel bunkers to overall CO2 emissions, those emissions make 8.48% of that new total UK CO2 emissions.

As for other Gases, well, as previously mentioned, planes spew out a lot of nasty stuff that are most likely worse than CO2 in the short and long term. But a lot of bodies don’t report those emissions statistics. IATA and ATAG don’t mention any other gases than CO2 on their website. EASA states that European Aviation counts for 7% of total NOx emissions and that CO and SOx emissions have risen since 1990. The BEIS tracks CO2, CH4 (Methane), N2O and Fluorinated Gases, but not in great detail.

So who’s right?

Well, both really, Katherine is right that globally aviation produces globally 2-3% of man-made CO2, not counting for all the other poison that aeroplanes spew out. But Caroline is definitely right to say that CO2 is not the whole picture, and that Aviation is definitely responsible for more than 2-3% of the UK’s, what one might reasonably construe as ‘our’, greenhouse gas emissions, whether or not the Government feels the need to take responsibility for it.