There has been criticism on social media over delegates arriving at the UN Climate Change Conference COP27, in Sharm el-Sheikh, Egypt.
The day before the conference began, hundreds of environmental activists stopped private jets leaving Amsterdam’s Schiphol Airport, sitting in front of their wheels and cycling around the airfield.
How many private jets have been to Sharm el-Sheikh?
Data from FlightRadar24 shows that 36 private jets landed in Sharm el-Sheikh between November 4 and 6, when the summit began.
Another 64 landed in Cairo, including 24 from Sharm el-Sheikh.
The COP27 website states that delegates must use either airport.
Nine of the flights were from the UK, others from European countries including Italy, France and the Netherlands.
Two were from the United States in Cairo – one from Atlanta and one from Washington DC.
FlightRadar24 says there may have been more scheduled private flights that it was unable to track due to limited coverage in the area.
But fewer private jets appear to be flying to COP27 than to COP26, in 2021, in Glasgow – BBC Reality Check investigated their use at the time.
One reason for this may be that there have been fewer world leaders, so far, who have attended the Sharm el-Sheikh summit.
What is the carbon footprint of private jet travel?
Flights produce greenhouse gases – mainly carbon dioxide (CO2) – from burning fuel. These contribute to global warming.
Emissions per kilometer traveled are significantly lower than for any other mode of transport.
This varies considerably depending on:
But private jets generally produce far more emissions per passenger than commercial flights.
There are many different models of private jets, but the one that flew most often in Egypt before Cop27 was the Gulfstream G650, which uses around 500 gallons (1,893 liters) of fuel per hour.
If a private jet had managed to take off from Amsterdam – despite the protests – it would have taken around five hours to reach Sharm el-Sheikh, consuming around 9,465 liters of aviation fuel.
The Department for Business, Energy and Industrial Strategy (BEIS) reports that 2.5 kg (5.5 lb) of CO2 is emitted for every liter of jet fuel burned. This flight would therefore produce 23.9 tonnes.
But to “capture the maximum climate impact” of flights, BEIS recommends, the CO2 emissions figures should be multiplied by 1.9 – to reflect the non-CO2 emissions emitted by aircraft at high altitudes, which scientists say increase the warming effect.
Therefore, the total emissions for this flight would be 45.3 tonnes of CO2 equivalent – and with a capacity of 15, each passenger would be responsible for approximately three tonnes during their journey.
These emissions figures are estimates for actual journeys – they do not include the emissions associated with manufacturing private jets in the first place.
If our COP27 delegates had opted for a commercial flight from Amsterdam to Egypt, assuming they were traveling premium class, their emissions would have been around half a ton each, according to the Organization’s calculator of international civil aviation (ICAO).
Even though a commercial flight consumes more fuel per hour, it can carry many more passengers than a private jet and therefore produces fewer emissions per person.
The British Prime Minister and Foreign Secretary arrived in an adapted RAF Voyager aircraft which is a version of the Airbus A330-MRTT.
Airbus told BBC News that a standard flight would use between 5 and 5.5 tonnes of aviation fuel per hour, depending on factors including the amount of cargo and altitude.
Using government conversion factors, this means the flight to Sharm el-Sheikh will have emitted between 79 and 87 tonnes of CO2. Using the BEIS multiplier brings this to 150 to 165 tonnes of CO2 equivalent.
BBC News asked Downing Street how many other passengers were on the flight to Sharm el-Sheikh, but Number 10 would not say.
A government spokesman said: “This delegation traveled on one of the most carbon efficient aircraft of its size in the world and the carbon emissions of these flights are also offset.”
International Head of the Energy and Climate Intelligence Unit told BBC News that focusing on world leaders taking private jets to COP27 was “missing the point”.
“The emissions are negligible compared to the impact of the decisions and commitments made at these summits,” he said.
“If you want emissions to go down, you want leaders in the room and the media, scientists and stakeholders to ask the important questions.”
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