2.3 Scope – aviation

Aviation adds an extra issue – the effect of water vapour ejected at high altitude (contrails) means that flights have a much greater contribution to global climate change than solely from their CO₂ emissions. This is sometimes called the radiative forcing effect, and some carbon footprint calculators take it into account. You will also need to consider the differing emissions from long- or short-haul flights, and for flying in different classes to provide an accurate footprint.