The growth of ride-hailing has directly contributed to increased local pollution and exacerbated traffic congestion in dense urban areas, according to a new report. Uber

Ride-hailing companies like Uber and Lyft have experienced exponential growth in a short period of time. The expansion of these services is changing transportation, but that rapid growth also comes with significant risks.

A new report, “Ride-Hailing’s Climate Risks: Steering a Growing Industry Toward a Clean Transportation Future,” by the Union of Concerned Scientists (UCS), finds that the rising use of ride-hailing services is increasing carbon emissions, with ride-hailing trips producing nearly 70 percent greater emissions compared to the trips they are replacing. This dramatic increase in emissions comes in part from “deadheading,” the increased miles a driver travels waiting for a ride request or picking up a passenger. In addition, ride-hailing trips frequently replace lower-carbon transportation methods — such as public transit, walking, or biking — that consumers might have used otherwise.

Even when compared to trips made in private vehicles, non-pooled ride-hailing trips on average produce almost 50 percent more emissions, UCS found. With ride-hailing services now providing more trips nationally than taxis, the growth of ride-hailing has directly contributed to increased local pollution and exacerbated traffic congestion in dense urban areas.

“Despite these troubling findings about their climate impacts, ride-hailing services still have the potential to be part of a cleaner, low-carbon transportation future,” said Don Anair, deputy director of the UCS Clean Transportation Program and lead author of the report. “Through electrification of vehicles and increased use of pooled rides, we can reduce the climate risks of ride-hailing services.”

The UCS report found that a pooled ride-hailing trip results in emissions similar to a private vehicle trip. An electric ride-hailing trip can cut emissions by about 50 percent compared to the average private car trip, while an electric and pooled ride-hailing trip can reduce emissions by about 70 percent compared to the average private car trip.

“The responsibility for change lies first and foremost with the ride-hailing companies themselves,” said Jeremy Martin, senior scientist and director of fuel policy at UCS. “Ride-hailing companies should take steps to reduce emissions by supporting their drivers in adopting electric vehicles, increasing pooling of rides, and encouraging travel by cleaner modes such as transit, walking, and biking where feasible. Ride-hailing companies should work to make sure their services complement, rather than replace, these lower-carbon options.”

Comparison of CO2-equivalent emissions from an average gasoline-powered personal car trip, a non-pooled TNC trip, bus and rail trips, and a mixed mode with 25 percent pooled TNC ride and 75 percent rail. UCS

• UCS experts recommend that companies encourage the use of electric cars by offering attractive electric vehicle-lease rates to drivers who lease vehicles for use on their platforms.

• They also suggest companies work with charging infrastructure providers to increase access to convenient charging for ride-hailing drivers.

• They can also encourage shared ridership by discounting pooled trips to make them more affordable.

Lyft and Uber have taken some steps to begin to address the climate impacts of their services.

• For example, last fall Lyft announced a program in Denver to deploy 200 electric vehicles in ride-hailing service.

• Uber announced per-ride driver incentives of up to $20 per week in some cities through their electrification initiative.

• Both companies are partnering with transit agencies in various ways, including pilot projects to help people get to or from transit as well as beginning to incorporate transit information into their apps.

• Lyft has also unveiled a carbon-offset initiative, though programs like this are not a substitute for reducing emissions and congestion.

These companies will need to put in greater effort to substantially reduce emissions and congestion coming from ride-hailing trips.

“The rapid growth of ride-hailing services has cities scrambling to keep up, and much work remains to implement effective policies addressing pollution and congestion,” said Martin. “Policymakers need to ensure that ride-hailing companies take steps to reduce their environmental impact, and ensure that people have a range of clean, safe, accessible, and affordable transportation options. Some policies cities and states should consider include discounting fees on ride-hailing for pooled and electric rides, incentive programs for electric vehicles and charging infrastructure, setting pollution standards for companies, and increased investment in public transit.”

The report suggests that while ride-hailing companies and policymakers bear the biggest responsibility in limiting ride-hailing’s negative impacts, individuals can help.

• Traveling by transit, walking, or biking when and where possible are the best choices for the climate.

• And when using ride-hailing, choosing a pooled or shared ride where available, or using ride-hailing to connect to mass transit, are good options.

• Selecting an electric ride is a good choice as well, though only in a few markets, including Seattle, do riders have this option.

“Ride-hailing services are continuing to grow — so companies like Lyft and Uber, policymakers, and consumers all need to make smart choices now to steer ride-hailing in a cleaner direction,” said Anair. “Ride-hailing can be part of a low-carbon transportation system. But it can’t happen without meaningful action from these companies and from policymakers.”