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Research article

Navigating the Climate Conferences: Comparing the Carbon Footprint of Private Jet Travel and Other Modes of Transport to COP28

Authors
  • Carole Roberts orcid logo (university college london)
  • Simon Chin-Yee orcid logo (university college london)
  • Richard Taylor orcid logo (university college london)
  • Mark Maslin orcid logo (university college london)
  • Lisa Vanhala orcid logo (university college london)
  • Penlope Yaguma orcid logo (university college london)
  • Jacqueline McGlade orcid logo (university college london)
  • Priti Parikh orcid logo (university college london)

This article is a preprint currently under revision.

Abstract

The annual Conference of the Parties (COP) meetings are pivotal events for collective action to combat climate change. This year, as world leaders, government officials and observers convene in Dubai, UAE, for COP28, climate justice will be a central theme. In light of these negotiations, we present an updated version of UCL’s carbon footprint calculator to compare different modes of transport from the UK to COP28 in Dubai. Analysing private jet data from the 2022 COP27 in Sharm El-Sheikh, Egypt, we then investigate the carbon footprint of private jet travel to COP28. The carbon footprint calculator demonstrates the carbon inefficiency of air travel compared to alternative modes of transport to COP28. As the most polluting form of transport, the carbon footprint of private jets is disproportionately high. We find that for a journey from London to Dubai, private jet travel is 9 times more polluting than a commercial flight, 35 times more than train transport and 52 times more than coach travel. Given the primary objective of COP conferences to discuss and negotiate climate change policies and actions, the use of private jets by prominent individuals undermines the core mission of these discussions. The research calls for transparency, accountability and informed choices in travel decisions to align with climate change commitments. Additionally, we explore the significance of the chosen COP venue in promoting equity, the associated carbon footprint and the influence of the hosting nation on negotiations.

Keywords: : Carbon footprint, Climate change, COP, Private jet, Transport, Environmental policy and practice, Environmental justice and inequality/inequity

Preprint Under Review
License
Creative Commons Attribution 4.0

 Open peer review from Stephen Blenkinsop

Review
The paper is well written although would benefit from a more clearly defined aim and better structured discussion. The significance of the results needs to be better contextualised as the potential significance of these isn't clearly articulated - are these not just an expected function of distance? These main points are detailed in 3-6 below.

MAIN COMMENTS
1.In several places elements of the the methodology requires further explanation:
i. P5; can you state how the data gaps referred to are dealt with?
ii. P5; a little more explanation of the multiplier is needed to justify its application. Also, what are the indirect effects? Is the multiplier applied after or before the conversion to CO2 equivalents? If after, it would be better describing it where equivalents are discussed.
iii. P6; Can you first explain what a load factor is? Also how is the load factor itself used?
iv. P6; Do you attribute all these flights to COP27 or do you just attribute those above average outside the COP period? Would it be most appropriate to do the latter?
v. P7; In the last paragraph, can you add detail of how the carbon footprint was derived from the tool. Were all these individual journeys entered into the tool?

2. P10; Carbon intensity needs defining somewhere - it isn't clear how the discussion around the figures quoted differ from the figures in the previous paragraph. Some differentiation between these two metrics is required. Also, more clarity would be useful in the last paragraph in terms of how the number of people equivalent is derived - is this derived from the carbon footprint (in Figure 6) or the carbon intensity (in Figure 7)?

3. P13; in terms of the main result, the carbon footprints seem unremarkable in that they just reflect the distance from London e.g. COP26 is the lowest. This analysis seems rather obvious unless I am missing something and would remove it or alternatively better explain the value and novelty of the analysis undertaken. Similarly, the result presented on P18 also seems unremarkable – the lowest carbon footprint is achieved by taking the option with the shortest flight. Also, the paper is about private jet travel, are those with access to a private jet likely to travel to Istanbul via coach to lower their emissions? Some indication of the relative journey times would also seem to be an important consideration if the aim of this information is to empower people to make decisions.


4. P15-16; much of the discussion in the section Environmental Impact of Aviation seems to be a methodological discussion rather than a discussion of the actual results e.g. the indirect effects of aviation and how relevant this is to private jet travel. Consider how much of this information is needed and where it might more appropriately sit in the paper.

5. P18; The points made in the final paragraph of the discussion don’t clearly sit within the context of comparing the carbon footprint of private jet travel and other modes of transport or could these be brought into a wider ranging discussion of locations for COP meetings that somehow incorporates the analyses undertaken in this paper? Similarly, the closing paragraph of the conclusion also states that the paper considers the choice of location for COP, but this is not clearly articulated in the introduction as an aim of the paper. In this regard, the results relating to location seem to be because of the use of London as a starting point. Would addressing this question not require an analysis of which potential location(s) would minimise emissions given the origins of delegates? This is also a different issue to that posed in the paper title which relates to the use of private jets. Consequently, some general thinking and articulation about the aim of the paper is required – is this a paper about the quantification of the emissions associated with private jet travel, a more general critique of such travel, or an assessment of potential locations for COP? This isn’t clear and needs to be better articulated in the paper introduction.

6. In terms of the conclusions, these would benefit from the inclusion of some headline quantitative information from the paper to convey the key messages and need some reframing in the context of point 5. Further, where you state the work empowers participants to make informed choices, it provides them with information but does it really empower them, what are the other barriers to change and what more action might be needed to effect change?


MINOR COMMENTS
1. P3; Instead of ‘After last year’s’ state the year
2. P3; can you state whether the figure of 50,000 is related purely to private jet travel or more generally to this population.
3. P6; What is meant by empty lags here?
4. P9; Presumably the journeys to COP28 are hypothetical journeys. I think this should be made explicit in the text. Also in this section can you make explicit whether this approach refers to a private or commercial flight.
5. P9; In the discussion of Figure 5 it would be helpful to refer to route 4 in the figure. In the caption for Figure 5 it would be useful to provide an explicit description of routes 1 -4 i.e. name locations 1-4 and make explicit whether private or commercial flights are referred to. Can you also explain/justify the choice of car and whether this apply to electric, diesel and petrol?
6. P16; delete reference to conference that will take place in the future.
7. P17; States that ‘Showcasing a lack of commitment to sustainable practices shapes public opinion and influences the behaviour of others’ but is there evidence to support this?
8. P17; Refers to domestic EU private flights <500 km as short-haul but should these not be medium haul according to earlier in the paragraph.

Note:
This review refers to round 1 of peer review.

 Open peer review from Markus Funke

Review

Review information

DOI:: 10.14293/S2199-1006.1.SOR-EARTH.AUJDMK.v1.RXYTFA
License:
This work has been published open access under Creative Commons Attribution License CC BY 4.0 , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com .

ScienceOpen disciplines: Environmental change , Environmental management, Policy & Planning , Geography
Keywords: Environmental justice and inequality/inequity , Transport , Climate change , Private jet , Carbon footprint , COP , Environmental policy and practice

Review text

Summary
==========

This work heavily builds up on previous results from Barnsley et al. 2022, presenting an extension of Barnsley et al.'s carbon footprint calculator by incorporating travel emissions arising from private jet travel to the UN Climate Change Convention Conference of the Parties (COP) 2023, held in Dubai, UAE. The results of the calculation emphasise the high environmental impact and significant low efficiency of private jet travel compared to commercial flights and ground travel.

In general, the topic of considering private jets as a travel option is of great importance to both the research community and the actual participants attending conferences. Research in that direction helps (i) to raise awareness and (ii) to provide a mechanism to actually measure the impact. Also, the language used in the article is of good quality and easy to follow.

While the paper addresses an interesting research angle, the lack of methodological rigour poses challenges to the validity of the results, and, most importantly, the discussion appears to be insufficient and inadequate, which may impact the attainment of a comprehensive and balanced research outcome. Given these major concerns, I recommend rejecting the paper in its current form.

Detailed comments
==========

Major concern I - methodological rigour
+++++++++

The methodology section consists of several shortcomings resulting in an overall unclear and intransparent study design.

- To compute the private jet travel data, Flightradar24 was used. However, as the work clearly states, this platform allows "aircraft owners privacy options to restrict information" and "Data gaps are, however, present due to reduced coverage over the region". Even though this is indeed a valid point, it needs to be discussed rigorously as a potential threat to validity and whether or what kind of strategy has been implemented to mitigate this threat.

- Considering the main contribution of this research, the methodology provided for the calculation of private jet travel emissions is not sufficient. On page 6, the methodology is briefly outlined. It is stated that the UCL carbon footprint was used to calculate the emissions. However, the work introduces the "load factor" as an additional variable. It is not clear how this load factor influences the overall calculation and how it was incorporated into the existing calculator.

- also, it raises the question whether the aircraft type influences the calculation or not. It remains unclear if a private jet has the same emissions as a commercial airplane. This circumstance should be considered and discussed. For instance, a concrete example such as Cessna versus Boeing 777 would help.

- Further, the method uses the "average occupancy of private flights in Europe as 4.7 passengers per flight". Apparently, this year's COP edition is based in Dubai, UAE, Asia. It remains unclear whether the factor is also valid for flights outside Europe and intercontinental flights. Again, it needs to be discussed rigorously as a potential threat to validity and whether or what kind of strategy has been implemented to mitigate this threat.

- The same holds for the "average capacity (7.4 passengers) of the most popular aircraft in Europe".

- Beyond the different factors, it is not apparent how the formula for the "private jet passenger load factor" on page 6 emerged. It should be explained whether the formula is based on other research or other basic mathematical models. In its current form, it is presented only without rationale. Also, a concrete example with actual numbers might help to fit it better into the context.

- As stated multiple times, the present work extents on the UCL carbon footprint calculator. However, one of the main contributions of the work by Barnsley et al. 2022 is the "carbon-time efficiency". It remains unclear why the present work does not consider this factor when calculating the footprint of private jets.

Major concern II - insufficient and inadequate discussion
+++++++++

The most important concern arises in the discussion section.

- Section Environmental impact of aviation: while the discussion presents indeed interesting and sound arguments around the impact of flying, the link to the present research and its results is completely missing. Paragraphs 2, 3 and 4 of this section do not even mention the results around the emissions of the private aviation sector. This does not represent an appropriate and analytical interpretation of the results obtained. It remains as background or introduction to the research topic.

- Section The location and context of COP28: while the first paragraph discusses the difficulties to travel to the COP28 location, the second paragraph remains as a social-political reflection which is out of scope of this study. The mentioned aspects are not related to the study at hand and do not reflect on the results obtained.

- Removing these two sections, the section Private jet travel to climate meetings remains: While this section fairly discusses the results obtained, some passages raises some questions. For instance, "[...] use of private jets by high-profile individuals clearly undermines this goal. Such use is a symbol of excess and disregard for the environment, undermining the credibility of the attendees and the conference itself. Showcasing a lack of commitment to sustainable practices shapes public opinion and influences the behaviour of others." While these are fair points, they remain again as social-political reflection without link to the results at hand.

Other comments
==========

- The abstract clearly states the intention of an updated version of "UCL's carbon footprint calculator". Also, the Methodology - COP27 private jet data section indicates an incorporation of "various updates". However, throughout the study, it becomes not clear which concrete parts of the calculator have actually been updated.  It appears that the calculator was reused and the routes to Dubai manually adjusted. Additionally, the private jet travel data has been calculated. From my point of view, I would argue that this research is an instantiation of the footprint calculator with an extension for private jet travel data.

- At several points throughout the study, COP 27 is considered and recalculated. It is not clear why COP 27 was considered for this study in the first place, as the work clearly states the focus of COP 28. Indeed, a comparison to COP 27 might be useful; however, the methodology about private jet data on page 4 are introduced based on COP 27. This remains unclear and should be better explained in the beginning of the paper.

- What is the acronym MLAT on page 4? Acronyms should always be introduced before using them.

- On page 5 "FlightConnections" is used. It remains unclear what this term refers to.

- On page 6, Results, the work underlines the data peak on the 9th November 2022. It would be interesting to discuss or at least outline what events happened at this date to provide an interpretation of this data peak. An idea could be to consider the agenda for COP27 (if available) and interpret/compare the events on this particular date. This might answer the question "why this peak?"

- Figure 4 and the text on page 7 are not in line. While page 7 states "The total carbon footprint of private jet flights to and from Cairo International Airport", figure 4 states "Comparison of carbon footprint per passenger". This results in "total carbon footprint" vs. "footprint per passenger". This problem should be solved.

- On page 10, 2nd paragraph it states "Based on the most frequently flown private aircraft types to COP27, a private jet journey to COP28 would release between 7735 to 11,154 kgCO2e per passenger (Figure 6)." It is not clear why the data are based on COP27 and the journey to COP28 "_would_" release a certain impact? I thought COP28 was particularly calculated. This should be revised.

- The term "carbon intensity" is used on page 10 but was not introduced/defined before. The term should be defined before.

- The last paragraph on page 10 appears to be the most important take-away message among all the results. This should be better highlighted. Maybe it can be better positioned and extended?

- All figures on page 11 do not consider private jet travelling. It remains unclear why these figures are presented. Can the data from private jet be incorporated?



Note:
This review refers to round 1 of peer review.