Thread by @JefimVogel

✈️Can Leeds meet its climate targets if Leeds City Council allows expansion of Leeds Bradford Airport (LBA)?

No.

Is LBA’s own climate impact assessment accurate?

No.

Here’s the latest evidence. I urge Leeds City Plans Panel to
read this and act on it conscientiously.

THREAD

2/ Leeds City Council has adopted a CO2 target for Leeds based on a CO2 budget in line with 66% chance of staying below 1.5 C (black dotted curve) and committed to work towards net-zero CO2 by 2030, roughly met by @LeedsClimateCom's net-zero 2033 trajectory (grey dotted curve).

3/ Both trajectories exclude LBA emissions (~18% of Leeds emissions). I adjusted them to account for LBA emissions. Dark green dotted curve = budget-based CO2 target for Leeds incl. LBA; light green dotted curve = net-zero 2033 trajectory scaled by current share of LBA emissions.

4/ As the CCC recognises, all sectors must reduce emissions. So LBA emissions should decrease roughly in line with the CO2 target for Leeds incl. LBA, if we are to sustain essentials (food, warm homes, health care, education, public transport etc.) within our tight carbon budget.

5/ We can derive a pro-rata CO2 target for LBA by allocating to LBA a fixed proportion of the annual CO2 target for Leeds incl. LBA, based on LBA’s current share in Leeds emissions (dark green / light green dashed curves, based on the respective dotted curves for Leeds incl. LBA)

6/ How do LBA emissions in case of expansion (red curve) fit with those CO2 targets? They don’t. While the targets require that LBA emissions DECREASE rapidly, expansion would see LBA emissions INCREASE steeply and vastly exceed the CO2 allowance for the whole of Leeds incl. LBA.

7/ The steep increase in LBA emissions between 2024--2030 is due to the rise in passenger numbers which the expansion is aimed at. LBA is not clear about passenger goals post-2030 but draws up a vague scenario of constant passenger numbers post-2030 and technological progress.

8/ IF LBA passenger numbers actually stayed constant post-2030 (probably a best-case after expansion), LBA emissions post-2030 would decrease ever-so-slowly (due to efficiency improvements) - but still exceed the CO2 targets for all of Leeds incl. LBA by miles (well, mega-tonnes)

9/ For the red curve, LBA emissions are calculated as emissions from baseline departure flights + ALL additional flights due to expansion. That’s exactly what LCC (rightly) requested, recognising that ALL additional flights above baseline would be facilitated by the expansion.

10/ Some may argue regardless that one should only count departure flights, i.e. exclude additional arrivals. I've tested it (orange dashed curve). Does that change our previous conclusion? No. LBA emissions would still exceed the CO2 targets for the whole of Leeds (incl. LBA).

11/ For comparison, I’ve also calculated all emissions associated with LBA, i.e. emissions from both departure and arrival flights (dark red dashed curve), to show the total climate impact associated with LBA operation (= the climate impact that would be avoided if LBA shut down)

12/ Here is the whole story (thus far) in one graph. From this analysis, it is clear that no matter how you twist it and turn it: expansion of Leeds Bradford Airport would be incompatible with Leeds’ climate targets, making it virtually impossible for Leeds to meet these targets.

13/ For those who like it simple, here’s a simplified version of the graph with just the main message: LBA expansion blows Leeds climate targets irreconcilably.

14/ And for those who are not convinced by LBA’s vague post-2030 passenger goals, here is the same graph just for the period until 2030 (when expansion is supposed to be complete and when Leeds is supposed to reach net-zero emissions).

15/ Does LBA admit the devastating climate impact of the expansion? Not quite. LBA’s Environmental Statement admits that “GHG emissions from the Development are potentially significant adverse” (p.34) - but dramatically underestimates (or downplays?) the magnitude of the impacts.

16/ How? First, LBA excludes non-CO2 effects. The total warming effect of aviation, including non-CO2 effects, is roughly 3x as large as the effect of flight CO2 emissions alone (Lee et al. 2020). Excluding non-CO2 effects means underestimating impacts per flight by a factor of 3

17/ This figure from Lee et al. (2020) shows: the probability of the effect of non-CO2 radiative forcing being zero or negative is tiny. Not accounting for non-CO2 effects corresponds to the assumption that their (most likely) effect is zero. This assumption is very likely wrong.

18/ This means that LBA’s current emissions as well as baseline emissions (no-expansion case) are ~3x as high as LBA claims (286%). That's a BIG underestimate. But it gets even worse.

19/ Second, LBA counts only the emissions of departure flights and hence excludes additional arrival flights due to the expansion (i.e. they exclude half of all additional flights due to the expansion), even though LCC has (rightly) explicitly requested to include them.

20/ The effects of LBA’s exclusion of additional arrival flights compounds with their exclusion of non-CO2 effects. With the expansion, LBA’s emissions would be ~4x as high as LBA claims (372%).

21/ Due to these exclusions, LBA underestimates the change in emissions due to the expansion by a factor of 6! And it gets even worse...

22/ Third, in their comparison with Leeds’ climate targets (Leeds Carbon Roadmap). LBA excludes international flights (which constitute >90% of LBA flight emissions). This exclusion means underestimating LBA’s climate impact by more than a factor 10!

23/ LBA’s exclusion of international flights compounds with their exclusion of non-CO2 effects and additional arrival flights. In fact, with expansion, LBA emissions in 2030 would be MORE THAN 30x AS HIGH (3383%) as what LBA claims in their comparison to Leeds’ CO2 targets. 30x!!

24/ LBA’s claimed that LBA emissions in 2030 in case of expansion would correspond to only ~5% of Leeds’ CO2 target. That's utterly wrong. In fact, LBA emissions would amount to more than 180% of Leeds’ CO2 target and thus completely blow the CO2 target for the whole of Leeds.

25/ If the expansion goes ahead, LBA’s cumulative emissions until 2050 would use up and exceed Leeds’ entire carbon budget until 2050.
How can we square that with our (as yet) carbon-intensive needs for transport, electricity and heating homes, schools and hospitals? We can’t.

26/ In summary, LBA’s climate impact assessment is heavily flawed: it dramatically and systematically underestimates the climate impact of the expansion. Once these flaws are corrected, it is clear that LBA expansion would be fundamentally incompatible with Leeds’ climate targets

27/ All data shown here draw on LBA’s Environmental Statement, however correcting LBA’s figures for the omitted non-CO2 effects and additional arrival flights due to expansion (as indicated), thus combining LBA’s intel on flight operations with more adequate emissions accounting.

28/ Annual data shown here involve linear (2020—2024) and logistic (2024—2030) interpolations between the sparse data points provided by LBA.

29/ Many of the points I made in this thread are also explained (partly in more detail) in this talk I gave a couple of months ago:

END/ Thanks for reading this long thread. Now please spread the word to all those who need to hear (read) it. Importantly, please make sure that the City Plans Panel reads this, and make sure they hear your voice on this issue. They have to be accountable to the people of Leeds.