The potential for reducing the impact of aviation on climate

The paper reviews the technical options available for reducing the impact of air travel on the Earth's climate. The three main impacts come from the emission of CO2 and NOx and the creation of contrails and cirrus cloud. The long-term potential for reducing CO2 emission is considerable, though bounded by the laws of physics. There is still greater potential for reducing NOx emission and contrail formation, although a measure to reduce any one emission can in some cases increase one or both of the others. Ideally, a balance has to be struck which minimises the total climate impact of all three. There is not yet a robust scientific basis for judging this balance. Even so, the paper outlines the technical possibilities for reducing climate impact and offers a conjectural estimate of their potential effect, when deployed in combination, on the future emissions of the world civil aircraft fleet.