Study Shows How Electric Transport and Urban Design Get Us to Climate Targets

New research suggests electric cars alone won't save us.

Transport in Berlin
Bikes, people walking, and streetcars in Berlin.

Lloyd Alter

New research from the Institute for Transportation Development Policy (ITDP) and the University of California, Davis (UC Davis) concludes that electric cars on their own won't save us—the only way we can keep under 2.7 degrees Fahrenheit (1.5 degrees Celsius) of warming is a combination of electrification and increased urban density. Lewis Fulton of UC Davis and D. Taylor Reich of ITDP, the lead authors of the report, titled "The Compact City Scenario—Electrified," ran the numbers on four scenarios:

Compact Cities Scenarios


  • Business as Usual (BAU) where we keep building and driving internal combustion engine (ICE) powered cars, with more than two billion new cars by 2050.
  • High EV where all the cars are electrified at the rate announced at COP26, with ICE vehicle sales phased out by 2040.
  • High Shift where land use is shifted to compact mixed-use design, much like that shown in our post how do we build in a climate crisis. "In the high Shift world, it is easier to get around cities by walking, cycling, or riding transit than it is by driving, and so the demand for cars is reduced. While global car use increases slightly due to population growth, it is far lower than under BAU or High EV."
  • EV+Shift where a combination of High Shift compact design in walkable cities and electrification of all the vehicles.

The problem with the high electric vehicle (EV) scenario is that while the cars and trucks might not emit greenhouse gases in their exhaust, it will take far too long to switch them all over. They will need vast new sources of clean electric power. And, notably, the report takes into account the embodied carbon or upfront carbon emissions from manufacturing and the infrastructure that supports them, which we have noted is an important but ignored issue.

"Our scope is not limited to greenhouse gas emissions from the operation of vehicles (“Well-to-Wheel”). Rather, we include emissions from vehicle manufacture and disposal, which is especially important for electric vehicles because of the carbon-intensive processes of creating batteries. We also include emissions from the construction and maintenance of infrastructure, including roads, rails, bicycle lanes, and parking spaces."

On the first review, I thought their upfront carbon accounting was too low, but they have that covered too. They write: "For vehicle production, disposal, and infrastructure, we assume fairly strong decarbonization, on the order of 50–60% between now and 2050."

Emissions from transport


Including the embodied carbon, or the emissions from manufacturing, means that those dark blue chunks of manufacturing emissions matter; going all-electric doesn't mean that in the full life cycle, emissions disappear. They are as big as the operating emissions that come from the grid not being entirely electrified.

Electricity consumption


The biggest difference between just going High EV and combining High EV with High Shift is the number of cars on the road–about 300 million fewer. This also adds up to a massive reduction in the amount of electricity required to run the transport system.

different scenarios


Put it all together and the electrification of transport plus the shift to compact design is the only scenario that reduces emissions enough to stay below the curve representing the decline in emissions necessary to keep global heating below 2.7 degrees F (1.5 degrees C). Or as ITDP CEO Heather Thompson says in a press release:

“We need electrification, but we will not meet our 1.5°C target if we focus on electric vehicles alone. We need to also focus on the fundamental equation of driving less, even if in electric vehicles, which still require a lot of resources like clean electricity. We need high-density development that provides better access to employment, education, and services for families of all income levels without being dependent on cars. Walkable and cycling cities aren’t just better for the economy and the environment—they're healthier and happier for everyone. We have the evidence, and we know what needs to be done: we need an integrated approach that includes both electrification and compact development. Cities must step up."
Summary of the LCGE and population accommodated with a fixed land area for the four urban typologies.
Summary of the LCGE and population accommodated with a fixed land area for the four urban typologies.

npj Urban Sustainability

Notably absent from the report is the discussion of the carbon emissions that come with the change in building form that comes with compact cities. In an earlier post about the Goldilocks density delivering the lowest lifecycle carbon emissions, we noted research by Francesco Pomponi demonstrating that High Density Low Rise (HDLR) design such as you would have in compact cities of the kind the ITDP is proposing, has less than half the Life Cycle GHG Emissions (LCGE per capita than Low Density Low Rise (LDLR) designs. And I complained in that post that "the study did not take transportation into account, which has much lower impact per capita at high density than at low."

Now the ITDP tells the transportation side of the story but misses the built form side. One of the study authors, Taylor Reich, acknowledges this, telling Treehugger that "we're a transportation consultancy and that is not our expertise."

The ITDP report emphasizes that urban form and transportation are interconnected, a point that we have long tried to make in Treehugger. In the conclusion of my book, "Living the 1.5 Degree Lifestyle," I channeled transportation planner Jarrett Walker and wrote, "How we live and how we get around are not two separate issues; they are two sides of the same coin, the same thing in different languages."

More recently, I wrote: "We have to stop talking about transportation emissions as something detached from building emissions. What we design and build determines how we get around (and vice versa) and you cannot separate the two. They are all Built Environment Emissions, and we have to deal with them together."

The ITDP report doesn't quite pull it altogether and deliver the picture of the full impact of the change in built form and the change in transportation, but the pieces are beginning to fall into place.

Reich also notes that beginning to implement the changes in transit that gets people out of cars, like busways and bike lanes, is a lot faster than waiting for electric cars.

“Timing is key, especially over the next ten years. Electric cars aren’t predicted to really go mainstream until the early2030s, but compact city policies are ready now. If we build public transit, cycleways and compact neighborhoods today, we can reduce the demand for fossil-fuel car ownership. Transit-oriented planning will pave the way for easier electrification, especially in rapidly growing cities.”

The compact city part of the equation takes a little longer and needs something else.

“It’s ambitious to say we can phase out internal-combustion engines by 2040, and it’s ambitious to say we can redesign cities so that more than half of travel is by walking, cycling or public transit,” but these things are logistically and technologically feasible—all that’s missing is the political will.”
emmissions by mode


This graph really sums it all up, the difference that happens when you go from just electrifying all those cars in the High EV scenario or you keep 300 million of them off the road, switching to other modes of transport: greenhouse gases are about 40% lower. As well as needing electric cars, we need fewer cars, and for that, we need cities designed so that people can walk, bike, or take transit.

And that, again, is just transportation emissions; it doesn't include the changes in building form, the total Built Environment Emissions. That will be an even prettier picture.

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View Article Sources
  1. "The Compact City Scenario- Electrified." Institute for Transportation Development Policy, 2021.