At least three companies are hoping to reintroduce supersonic jets back into the world of commercial aviation, but a new study released by the International Council on Clean Transportation warns that this could be very bad for the environment.

Supersonic jets fly faster than the speed of sound and at higher altitudes than other commercial airliners. While other commercial planes can fly from Paris to New York in about eight hours, a supersonic jet could make the same trip in three and a half hours. British Airways and Air France offered Concorde supersonic service from 1976 to 2003, when high ticket prices and fears that were stoked by a 2000 crash that killed 113 people resulted in the service being discontinued.

Despite the challenges associated with offering supersonic commercial flights, the startups Boom Supersonic, Spike Aerospace and Aerion Supersonic are looking to bring these faster jets back to the skies.

It’s been estimated that supersonic jets will consume as much as five to seven percent more fuel per passenger than conventional jets. On top of that, there will always be far fewer passengers in a supersonic jet than on other commercial airliners due to higher ticket prices. All of it adds up to what many experts are calling a woefully inefficient method of travel. Passengers may reach their destination in half the time it would take them to get there via more conventional air travel, but it would be at a cost of a much greater carbon footprint.

Boom Supersonic has stated that they are working on making supersonic flight more sustainable that it has been in the past, with their goal being a supersonic jet that burns fuel as efficiently as a subsonic airliner. They also hope that this will lower ticket prices and make the service more affordable and accessible to everyone.

Whether these new supersonic flight services will truly take off remains to be seen. If these companies can truly make these services more sustainable and environmentally-friendly, we may not have as much to worry about as we think. Still, history has shown that commercial supersonic flight may be more trouble than it is worth. The damage to the environment and the high ticket prices might not be worth reaching your destination just a few hours earlier than you otherwise would.