A significant amount of time, effort, capital, brainpower and, yes, energy is being spent developing solutions intended to cut transportation’s greenhouse gas emissions. Many of these efforts — such as self-driving cars and electric vertical takeoff and landing air taxis — are laudable, incorporating cutting-edge technologies. But in our rush to address the myriad contributors to the climate crisis, we often fail to see the bigger picture of how these forces interact. Tackling one problem can lead to unforeseen consequences that inadvertently push the goal line further away.

While self-driving cars and robotaxis were once hailed as a solution to climate-harming congestion, they may actually make the climate situation worse. I believe they will have major unintended negative consequences with second- and third-order effects that will seriously undermine climate goals.

The Transportation Climate Problem

Transportation is now the U.S.’ leading source of greenhouse gas emissions, with cars, SUVs,  pickup trucks and minivans representing the largest share of that category. Carbon dioxide emissions from transportation have grown from 2021 to 2023 after a brief pandemic pause and are on track to increase.

Many other sectors of the U.S. economy have dramatically reduced their carbon dioxide emissions over the past two decades and continue to trend lower. Electric power generation, which was the top GHG source less than a decade ago, has cut emissions by more than 30% over the last 20 years.

A major reason transportation emissions are growing is that total vehicle miles traveled, or VMT, continues to grow and hit its highest recorded level last year. Every year, the tendency is for people to take more frequent and longer average trips, in part due to growing urban-suburban sprawl.

Self-driving Cars and Robotaxis = More Miles Traveled

Robotaxis will accelerate VMT growth even further. A 2022 Urban Institute report warned that despite some potential benefits, such as improving road safety and access to mobility, robotaxis may “produce several potential downsides for the transportation system,” one of them being “significantly higher VMT.”

Read the full article about the environmental costs of self-driving cars by Jeral Poskey at Smart Cities Dive.