There is no easy way out of “flight shame.” Swedish climate activist Greta Thunberg’s warnings against air travel seem to be having an effect, particularly in Europe. In a recent survey by Swiss bank UBS, 21% of respondents in the U.S., the U.K., Germany and France said they had cut back on flying this year. Perhaps more importantly, lawmakers are listening: Starting next year, France will impose a tax on outbound flight tickets. …