SOU (Southampton Airport) estimates that each passenger on a non-return flight to Bordeaux is responsible for 85.3 kg aviation CO2 emissions. [https://www.southamptonairport.com/media/6029/southampton-airport-public-information-session-materials.pdf page 8 ]. Assuming that only Bordeaux is served, this amounts to 170,000 tonnes CO2 each year that flights from Southampton airport account for, currently [this is more than 4 times what Eastleigh BC have calculated https://meetings.eastleigh.gov.uk/documents/g6531/Public%20reports%20pack%20Tuesday%2022-Oct-2019%2018.30%20Policy%20and%20Performance%20Scrutiny%20Panel.pdf?T=10 page 44 of the pack ]. This would be scheduled to rise to 340,000 tonnes by 2027 and 425,000 tonnes by 2037. These calculations do not take account of possible improvements in fuel efficiency by 2037 (which would reduce the tonnage). However neither do these calculations take account of ‘radiative forcing’ (contrails etc.) which would be conservatively set to double the effect of their levels.
The above graph (produced by MH) is a more sophisticated analysis based on analysis of the figures provided verbally by the author of the airport’s EIA. This takes account of 0.5% efficiency improvement with aircraft engine design and a more mixed fleet of aircraft. Nevertheless, applying radiative forcing would approximately double the emissions.
https://www.carbonindependent.org/22.html calculates a CO2 equivalent of 250 Kg (1/4 tonne) per passenger for each hour of flying.
A study by Southampton University has estimated that the trees of Southampton sequestre 2,684 tonnes of CO2 each year :[https://www.southampton.ac.uk/news/2018/02/southampton-trees.page] This means that Southampton would need more than 60 times as many trees as it has just to neutralise the effects of Southampton airport’s current aviation CO2 emissions.