Several major airlines have pledged to reach net-zero carbon emissions by midcentury. It’s an ambitious goal that will require an enormous ramp-up in sustainable aviation fuels, but that alone won’t be enough, our latest research shows. …Several airlines are already experimenting with sustainable aviation fuels. These include biofuels made from agriculture residues, trees, corn and used cooking oil. Other fuels are synthetic, made by combining captured carbon from the air and green hydrogen, made with renewable energy. …Replacing fossil jet fuel with sustainable aviation fuels will be crucial, but the industry will still need to invest in direct-air carbon capture and storage to offset emissions that can’t be cut. …It could require as much as 1.2 million square miles of dedicated land to grow corps to turn into fuel – roughly 19% of global cropland today. …Efficiency improvements will help decrease the amount of energy needed to power aviation, but it won’t eliminate it.