1. Air travel

The lifestyle carbon footprint covers personal behaviour so this target does not include flying for work. However, we encourage participants to take action at work too, particularly by avoiding flights using jet aircraft.

Taking a flight in a jet airliner is currently responsible for such a high level of carbon emissions on a per capita basis that it is extremely difficult to accommodate even one trip a year on a jet airliner within a 2.5 tCO₂e lifestyle. For example, using official UK government ‘conversion factors’ (BEIS, 2021), a return flight (economy class) from London to Hong Kong (nearly 10,000 km each way) leads to the equivalent of 2.9 tCO₂e once the additional heating effects of high-altitude flying are included, together with the lifecycle emissions of the fuel. Professor Mike Berners-Lee of Lancaster University, UK, argues that, if the relevant lifecycle emissions of the airline company are included as well, then this figure rises to 3.5 tCO₂e (Berners-Lee, 2020: 140-142). Even a return flight from London to Glasgow (only around 600 km each way) could be responsible for over 0.3 tCO₂e, including all lifecycle effects (Berners-Lee, 2020: 114-116). Travelling business class would nearly triple these figures, while going first class would roughly quadruple them (Berners-Lee, 2020: 140-142).

There are limited options for flying that might be compatible with a 2.5 tCO₂e lifestyle, but we have not yet included them within this current set of targets. These include flying on a jet airliner once every several years (depending on the distance travelled), and flying on a (lower impact) turboprop plane over distances up to a couple of hundred kilometres per year, where land transport is not available (e.g. for island travel). You are invited to explore these options further yourself.

There are also new technological options not yet deployed on a wide scale that may reduce the carbon emissions of flying, e.g. using biofuels, hydrogen, synthetic fuels, batteries or airships. From the information currently available – see, e.g. Asher (2022) – we think that none of these are likely to significantly reduce the carbon emissions of flying before 2030, so we do not consider them further here. However, we will continue to monitor developments in this area.