Apr 17, 2015 · 1 minute

Uber claims the UberPool ride-sharing service saved an estimated 120 metric tons of carbon emissions in San Francisco between February 20 and March 20.

That estimate is based on a few assumptions: that most UberPool riders were in a Toyota Prius, that each of those vehicles is getting its advertised mileage, and that every rider would have taken different routes had they ridden separately.

Here's Uber's math (emphasis theirs):

The miles savings estimate for San Francisco is the distance difference between the sum of the individual rider routes and the uberPOOL route, about 674,000 miles in aggregate from February 20th to March 20th. This method accounts for any small amount of additional distance an uberPOOL trip went to accommodate the two rider routes.

Conservatively assuming that every SF uberX vehicle is a Toyota Prius — thus getting its gas mileage of 50 mpg — uberPOOL trips saved around 13,500 gasoline gallons. Accounting for a savings of 8.91 kg of atmospheric CO2 emissions per gallon, San Francisco’s uberPOOL efforts prevented about 120 metric tons of CO2 emissions from Feb-Mar 20th, equivalent to the output of over 128,000 pounds of coal.  And every week as we keep growing, so do CO2 savings. That seems great. I like the environment! People using these pseudo-mass transit services to split rides instead of booking them individually could be good news. But none of this means that UberPool actually had much of an impact.

Other questions will have to be answered before a verdict can be made. Did people stop riding the bus or taking BART in favor of booking an UberPool with their friends? Did they stop driving their own cars in favor of this service? What type of vehicle was being driven, and how good was their actual performance?

If anything, Uber showed that it's better for the environment to take mass transit -- or at least to share a ride -- than to use its ride-on-demand service. UberPool is solving an environmental problem that Uber itself may have helped create.

[illustration by Hallie Bateman]