evidence: In less than two weeks, leaders from 196 countries and around 25,000 delegates, activists and protestors will descend on the Scottish city of Glasgow for the United Nation’s 26th global climate summit, or COP26. It is no small irony that most of them will travel by air, the most carbon intensive form of travel, emitting six times more CO2 per passenger mile than taking the train. The U.K., of course, is an island, so alternatives are limited. But even for those traveling from elsewhere in Great Britain, where trains are ubiquitous, it’s not an easy choice. A round-trip train ride from London to Glasgow costs nearly three times the price of an EasyJet flight, according to a quick search on the travel cost comparison site Omio.com.