There’s no way around the fact that flights are bad news for the environment. It’s not just that planes are worse than most other forms of transport in terms of the impact of greenhouse gases per passenger mile. Just as important is the simple fact that flying allows us to travel a far greater number of miles than we otherwise could. Thanks to these two factors, individual trips by air can have a remarkably large carbon footprint – which helps explain why aviation has become such a heated issue in the climate change debate.