Environmental groups are hoping to use Uber’s expected IPO next week to highlight the ride hail company’s contribution to climate change and rising carbon emissions. On Friday, the Sierra Club unveiled an ad campaign urging Uber and its rival Lyft to curb air pollution by switching to fully electric cars.

The timing of the ad campaign is crucial: next week, Uber is expected to make its public market debut at an eye-popping valuation of $90 billion, making it the biggest IPO since Alibaba in 2014. As Uber embarks on its roadshow to gin up support among investors, the Sierra Club wants the issue of Uber’s contribution to pollution and climate change to be at the top of everyone’s mind.

To be sure, Uber has weathered criticism about pollution and traffic congestion for years. And the company has tried to address it through a variety of means, including its bike- and scooter-sharing services, its effort to integrate public transportation scheduling and ticketing into its app, and its incentive program to get drivers to switch to electric cars.

But for the 127-year-old Sierra Club, those efforts fall short. “We need to see bolder plans from these companies that are valued at tens of billions of dollars,” said Andrew Linhardt, deputy advocacy director at the Sierra Club. “They can really make an impact, especially considering all the undue harm they’ve caused.”

For the environmental group, that undue harm can be split into two categories: increasing the number of vehicle miles traveled (VMT) in major cities and poaching riders from public transportation. According to Bruce Schaller, a transit consultant who served as deputy commissioner for traffic and planning in New York City, ride-hail companies like Uber and Lyft have added 5.7 billion miles of driving annually in cities like Boston, Chicago, Los Angeles, Miami, New York, Philadelphia, San Francisco, Seattle, and Washington, DC.

“They can really make an impact, especially considering all the undue harm they’ve caused.”

Uber has also faced criticism for its negative effects on public transportation in the US. Declining bus and subway ridership has been associated with thrise of Uber’s popularity in dozens of cities. According to Schaller, about 60 percent of Uber and Lyft riders in large, dense cities “would have taken public transportation, walked, biked or not made the trip” if ride-hailing had not been available.

Despite their efforts to promote themselves as a “last mile” connector to public transportation, both Uber and Lyft admit to being in competition with subways, buses, and trains as a mode of transportation. Linhardt cites Uber and Lyft’s respective ad campaigns targeting bus and subway riders in New York City. “Something about a company that’s comfortable running ads like this makes us suspicious of these other [efforts to help public transportation],” he said. “You need to go beyond just having a page on an app, otherwise it’s just green washing.”

Last year, Lyft announced a multimillion-dollar investment to become a completely carbon-neutral transportation service through the purchase of carbon offsets. Around the same time, Uber kicked off a yearlong pilot program to provide cash incentives to some North America-based drivers who use electric vehicles, with the goal of facilitating at least 5 million trips over the next 12 months.

Linhardt says those programs are good “first steps,” but they don’t come anywhere close to tackling the full breadth of the problem. “They need to put real funding behind these incentive programs, especially for full-time drivers, and get them more quickly into electric vehicles,” he said. “They have the market power to help shape the EV market.”