They can't be serious
It appears (and I am asking formal questions to confirm this) that the UK does not include the 8MtC of emissions from International Air Traffic in its approx 35MtC of transport emissions although it does include the single 1MtC of Domestic Traffic.
I presume the 8MtC is calculated on the basis of the next hop.
The total emissions is about 150-160MtC so this is 5% of the total.
No wonder they don't think an increase to 14MtC will have any impact on the UK's Kyoto figures - the Kyoto figures don't include international air traffic.