At first glance, the assertion that dockless electric scooters are more environmentally friendly than other modes of transportation seems sound. They don’t emit greenhouse gases. They don’t add to vehicle congestion. “Cruise past traffic and cut back on CO 2 emissions – one ride at a time,” touts Bird, one of the most popular scooter companies in the US.

But scooters are not as eco-friendly as they may seem, according to a study published on Friday.

Researchers at North Carolina State University found that traveling by scooter produces more greenhouse gas emissions per mile than traveling by bus, bicycle, moped or on foot.

The team discovered that while the scooters themselves were not particularly environmentally unfriendly, the materials it took to manufacture the frame, wheels and battery, as well as the companies’ efforts at the end of each day to round up the scooters, charge them and then return them to the streets, had significant impact when it came to greenhouse gas emissions.

“They claim that they’re Earth-friendly and potentially carbon-free,” said the study author Joe Hollingsworth. “What we found is while they might have zero tailpipe emissions, there are definitely upstream and downstream processes that definitely do not make the processes carbon-free.”

The researchers took apart the same model of scooter used for the first generation of Birds, and calculated the greenhouse gas emissions associated with putting it together. They determined that the materials and manufacturing made up about half of the scooter’s global warming impact, something that is only exacerbated when the scooters are vandalized or destroyed.

And scooters, in particular, are targets for vandalism and destruction. Bird Graveyard, an Instagram account started by three friends in west Los Angeles, has more than 99,600 followers who subscribe to their documentation of scooter vandalism. One of the founders of the account, who has never disclosed his name because of the nature of the material, told the Guardian on Friday that while he has always supported the concept behind the scooters – a transportation alternative to environmentally unfriendly cars – the rollout of the scooters has made them targets of vandalism.

“It’s a great idea, but it’s carried out very poorly,” he said. “People are going to do people things, and destroying it is just going to be part of it. They should have accounted for that at least somewhat and had something to counteract that.”

Bird and Lime did not immediately respond to requests for comment.

In 2018, people rode scooters on 38.5m trips, according to the National Association of City Transportation Officials.

Hollingsworth and the other researchers encouraged the scooter companies to “reduce collection and distribution burdens by incentivizing or requiring the use of efficient automobiles”, and centralizing management or “allowing chargers to ‘claim’ e-scooters to eliminate unnecessary and competitive driving during daily collection”.

“I hope that our paper helps consumers consider what they’re actually replacing with the scooters,” he said. “Hopefully, it will help these companies to better manage how their employees are driving around to pick these scooters up to make them more efficient.”