As delegates from around the world flew into Scotland for the COP26 climate change summit, Australia’s former foreign minister Alexander Downer weighed in on the climate impact of the attendees’ air travel.
“There are 400 private jets ferrying delegations to the COP26 conference. @POTUS [US President Joe Biden] brought five. It is estimated they will emit in 24 hours as much CO2 as Scotland emits in a year!,” Mr Downer wrote on Twitter.
Would 400 private jets emit as much carbon ferrying delegations into Glasgow in 24 hours as Scotland emits in a year? RMIT ABC Fact Check investigates.
Mr Downer’s claim is nonsense.
The Scottish government’s most recent estimate, from 2019, puts the country’s annual emissions for that year at 47.8 million tonnes of carbon dioxide equivalent.
It is not clear just how many private jets arrived in the UK for the Glasgow summit within 24 hours of Mr Downer’s claim, but Fact Check’s rough calculations for the emissions that could be generated by 400 private jet journeys are in the tens of thousands of tonnes.
This estimate is several thousand times smaller than the annual emissions of Scotland.
The source of the claim
Fact Check contacted Mr Downer via Twitter to ask for the source of his claim, but did not receive a response.
The headline of an article written for Scottish masthead the Daily Record on October 31 reads “Private jets flying to COP26 in Glasgow will blast more CO2 than Scots pump out in a year”.
In the description and body copy, the article clarifies that the flights would generate carbon emissions equal to the annual emissions of just 1,600 Scottish residents, under its calculations.
The article quotes anonymous “aviation sources” which “confirmed more than 400 private aircraft will likely carry over 1000 world leaders, business execs and their staff to the talks”.
How many private jets flew into Glasgow?
Fact Check could find no publicly available data on how many private jets enter Scotland or the UK on any particular day.
A spokesman for the UK’s Civil Aviation Authority told Fact Check the organisation did not collect that type of data, and suggested contacting NATS, a UK-based air traffic control company, formerly known as the National Air Traffic Control Service.
NATS did not respond to emailed enquiries by the time of publication.
Fact Check was unable to verify the exact number of private jets flying into Glasgow for the summit.
According to the COP26 website, around 120 leaders met in Glasgow on November 1 for the summit.
On November 4, the BBC, citing flight tracking website FlightRadar24, reported 182 non-commercial flights had landed in Glasgow, Prestwick and Edinburgh airports since October 27, excluding cargo, regular or local journeys.
This number, however, excludes some national chartered flights such as US President Joe Biden’s plane, Air Force One.
Aviation analytics company Cirium also told the BBC there were a total of 76 flights involving private jets, or VIP flights, arriving in and around Glasgow in the four days leading up to 1 November.
Calculating aircraft emissions
In May, Transport and Environment, a European non-governmental organisation focussed on reducing transport emissions, released a report which makes the case for reducing private jet travel.
The report calculates that a single private jet can emit 2 tonnes of CO2 per hour, based on a particular model of aircraft called a Cessna Citation Excel, on a London to Paris flight lasting about 55 minutes.
This calculation was drawn from a tool developed by the European Environment Agency, a European Union body with 32 member countries and 6 co-operating countries. The calculator asks for an aircraft model and flight distance in nautical miles as inputs.
Using these inputs it calculates the emissions generated by the LTO (landing and take off) phases and the CCS (climb/cruise/descent) phases.
Data analyst for Transport and Environment, Valentin Simon, told Fact Check that these phases generated emissions at different rates.
“Take-off and landing burn fuel much faster than during normal cruising, which is why an accurate calculator should consider the phases separately,” he told Fact Check in an email.
Other experts contacted by Fact Check agreed this tool was adequate to produce estimates of aviation emissions.
As previously mentioned, Fact Check was unable to independently verify how many private jets arrived in Scotland or the UK for the purpose of transporting delegates to the summit.
But using Mr Downer’s claim of 400, some rough calculations can be made which can be compared with the magnitude of Scotland’s annual emissions.
The Daily Record claimed “around 100 of the aircraft are believed to be carrying delegates from Europe — with most round trips taking on average four hours — while a further 300 long haul trips will clock up roughly 20 hours in the air.”
The article calculates that the 400 aircraft would emit 13,000 tonnes of carbon into the atmosphere ferrying delegates to and from the conference.
However, this calculation appears to be a product of the average emissions of a private jet in the Transport and Environment report (which the article references) and the total number of hours in the air for the 400 jets which the article asserted were involved, which would give a solution of 12,800 metric tonnes.
Mr Simon told Fact Check more accurate calculations could be made using distances matching the flight times in the EEA calculator.
He recommended using a Cessna Citation Excel (C550XL) for short-haul legs, assuming an average one-way trip of two hours, and a Bombardier Global Express (BD700) for long-haul legs, assuming an average one-way trip of 10 hours.
As an exercise, Fact Check has used the Daily Record’s splits of aircraft and average flight time to calculate the rough magnitude of emissions that would be generated from 400 flights.
However, Gianmarco Andreana, a PhD student in applied economics and management at the University of Bergamo in Italy cautioned that the calculator could sum emissions on average, but did not account for the emissions of civil aviation aircraft like the US President’s Air Force One.
“… their emission values can largely differ from the one computed by any emissions calculator (different engines, weights, instruments, airframe, etc…). This means that using the value provided by an emissions calculator will, generally, underestimate their effective environmental footprint,” he told Fact Check in an email.
For a one-way journey lasting 2 hours on the Cessna model, the calculator predicts 3.4 tonnes of carbon dioxide would be emitted. One hundred of those journeys would emit 342.8 tonnes, while 100 return journeys would emit 685.7 tonnes.
For a one-way journey lasting 10 hours on the Bombardier model, the calculator predicts 46.697 tonnes would be emitted. Three hundred of those journeys would produce 14,009.0 tonnes of carbon dioxide and the equivalent number of return journeys would produce 28,018.0 tonnes.
Summed together, this would equal 14,351.8 tonnes for all the one-way trips.
For return trips 28,703.6 tonnes would be emitted. However, it is unlikely that the bulk of the return journeys would be completed within the 24 hour time frame selected by Mr Downer.
How does this compare to Scotland’s annual emissions?
By comparison, the Scottish government’s most recent estimate of annual emissions puts the country’s carbon output at 47.8 million tonnes (47,800,000) of carbon dioxide equivalent.
This is over 3,000 times greater than the one-way journey estimates made by Fact Check.
To put the comparison between Scotland’s emissions and aviation emissions another way, if all 39,509 participants (provisionally estimated) attending the Glasgow conference each flew in their own Airbus A380 from Sydney, stopping in Dubai and then continuing on to Glasgow, these 39,509 individual one-stop, one-way journeys would generate approximately 33,554,586 tonnes of carbon dioxide, according to calculations made by Fact Check using the calculator.
This would still not be enough to match Scotland’s annual emissions output.
This calculation is obviously absurd, but equally it demonstrates the absurdity of comparing 400 private jet journeys with the annual emissions of a country the size of Scotland.
A study published in Global Environmental Change in 2019 calculated that the entire private jet sector emitted 33.7 million tonnes of carbon in 2016.