An initial assessment of departmental aviation emissions was carried out using air travel data from 2005-06 and the conversion factors published in Defra's Guidelines for Company Reporting on Greenhouse Gas Emissions. These factors are currently 0.11 kg CO2 per passenger kilometre for long-haul travel, and 0.15kg CO2 per passenger kilometre for short-haul. For the purposes of the government carbon offsetting fund, a multiplier of x2 has been applied to the estimated totals to take into account the additional climate impact of non-CO2 emissions at altitude.
To apply an offsetting cost figure to departments, the initial assessment emissions totals were multiplied by £10. This is based upon the price agreed per tonne CO2 for the offsetting of the UK's G8 presidency.
The actual cost per tonne to be paid will depend on the conclusion of the offsetting fund procurement process, due at the start of December. The initial assessment emissions figures will be updated using actual departmental air travel data for the opening year of the scheme, 2006-07. Final calculations of CO2 tonnage and associated offsetting costs will be carried out in April 2007.