Getting in an airplane long ago ceased to be anything remotely resembling a luxury experience. But in recent years, it has become something else as well - a largely unavoidable form of "climate sin." Although aviation is a relatively slim sliver of global carbon emissions - around 2.5 percent - at the personal level, it carries an enormous footprint practically unmatched by any other individual action. (Avoiding an international flight from New York City to London, for example, could save 600 kilograms of carbon dioxide from spewing into the atmosphere - about double the effect of going vegan for a year.) The climate activist Greta Thunberg once opted to take a high-speed racing yacht across the Atlantic rather than get in a plane; in her home country, Swedes have started using the word flygskam, which means "flying shame."
But despite the efforts of activists and climate scientists, most people are unlikely to give up flying. A new report by the nonprofit International Council on Clean Transportation suggests another way forward: A global tax on those who fly the most - the proceeds of which could be used to fund research and development into emissions-free aviation fuels.