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In California, 40 percent of greenhouse gas emissions come from transportation. Emissions from this sector will make it difficult to meet the state’s 2030 climate goals. There is a myriad of solutions: electric vehicles, public transportation, ride share, e-scooters and more. But people’s behaviors and habits as well as bad land-use planning make this one of the most difficult sectors to decarbonize. In this episode of Unfold, we’ll look at how we can transition to low-carbon transportation.

In this episode: 

Giovanni Circella, Director of 3 Revolutions Future Mobility Program, Institute of Transportation Studies at UC Davis

Lew Fulton, Sustainable Transportation Energy Pathways Program Director, Institute of Transportation Studies at UC Davis

Dan Sperling, founding Director of the Institute of Transportation Studies and California Air Resources Board Member

Amy Quinton:  Hey Kat, do remember last year?

Kat Kerlin: Yeah, life was better then.

Amy Quinton: Well I’m going to take you back, one day last December, for a moment, in your mind.

Kat Kerlin:  OK. 

Amy Quinton:  It was raining.

Kat Kerlin:  Wait, you remember it was raining?

Amy Quinton: Yeah, because back then I usually took the bus to work two or three days a week. I’d go across the causeway from Sacramento to Davis. It can take anywhere from 30 minutes to ---well once it took two hours. It depends on I-80 traffic. And when it rained, I hated it cause, I don’t like getting wet.

Kat Kerlin:  Yeah, super inconvenient. Princess. 

Amy Quinton: Well, I was going to campus to talk to one of our transportation experts about reducing greenhouse gases in our transportation sector. And so I thought well, it would be appropriate to take public transit that day. 

Kat Kerlin:  So you’re waiting in the rain for the bus.

Amy Quinton: Well actually, let’s fast forward. The bus has dropped me off on campus, only I need to get to the other side of campus across the highway. And some days, well you know me, I’m pretty lazy. 

Ok, so I’m outside the Mondavi Center and I just called an Uber to take me to the other side of campus, West Village, and I’ve been told it’s going to be $7 to take me 8 minutes away. I’m waiting on Tony and he’s in a Prius. 

Kat Kerlin: Wait, wait, wait….you took an Uber? You could have just hopped on Unitrans, the university’s bus system.

Amy Quinton: Shhh, don’t interrupt, I’m telling a story. So Tony shows up. Hi, are you Tony?

Tony: I sure am. You’re Amy, right? 

Amy Quinton:  Yes. 

Tony: Tilla street, huh? 

Amy Quinton: Yeah, not very far at all. So I strike up a conversation and tell him about this podcast episode. One of the things I’m looking at is reducing greenhouse gas emissions so I’m pleased you picked me up in a Prius. 

Tony: That’s cool. Well, believe me I would drive an electric car if I could afford one that had the range.

Amy Quinton:  Five minutes later.

Tony: Mam’ you have a nice day, ok? 

Amy Quinton: Thank you really appreciate it. 

Tony: Take care.

Kat Kerlin: OK, what was the point of that little scene?

Amy Quinton: Oh, I just wanted to reminisce. We’re not taking Uber as much during the pandemic and I wanted people to just remember what it was like.

Kat Kerlin: No really, Amy, what was the point?

Amy Quinton: Well I thought it was a great example of all the excuses we have for not doing the right thing when it comes to reducing our transportation carbon footprint.  

Kat Kerlin: But you didn’t take a car at first. You took a bus. That was a good start.

Amy Quinton: Yeah, well public transit is always better. But then again, I only take it a few days a week or I did before the pandemic which now has me working out of a closet. And I hardly ever take it if it’s raining.  

Kat Kerlin: Well using Uber isn’t that bad though. And he was driving a Prius.

Amy Quinton: A hybrid is good. But it’s not electric and well, Tony the driver thinks electric cars don’t have the range. And I found out that using ride-hailing services like Uber and Lyft may lead to an increase in the amount of vehicle miles traveled, especially if you’re using the service instead of taking public transit like I was.

Kat Kerlin: Or if the drivers aren’t in a hybrid or electric car. Well, it sounds like there’s going to be a lot to unfold about transportation. 

Amy Quinton: It’s a moving target.

Kat Kerlin: Your puns are just ridiculous, Amy.

Amy Quinton: Yeah, but it is a moving target, the pandemic has completely changed some of our transportation habits. And it keeps changing.

Kat Kerlin: You’re right, and we’ll be talking about that as well. Now let’s move on…

THEME Climate models all agree that temperatures are going to increase. It's going to be hotter. It's going to be drier. Fires are going to burn more frequently. Maybe this is never gonna be the way it was again. We need to come up with ways to literally pull CO2 out of the atmosphere. How are we going to work together to solve a challenge like climate change? 

Amy Quinton: Coming to you from our closet studios as we shelter in place across the Sacramento region, this is Unfold, a UC Davis podcast that breaks down complicated problems and discusses solutions. This week we unfold “transitioning to low-carbon transportation.” I’m Amy Quinton. 

Kat Kerlin: And I’m Kat Kerlin. Speaking of carbon, how carbon-intensive is transportation you might ask? Well it plays a huge role in our greenhouse gas emissions. It accounts for 40 percent of California’s emissions, about a third of US emissions and about 14 percent globally. 

Amy Quinton: In this episode, we’re going to be talking about solutions to our transportation emission problems, but we also need to get real. The main problem is us and our habits. I mean, who doesn’t love getting in their comfy car in the morning. You put your travel mug right in the little cup holder. You start the engine. And, if you’re like me you put on your favorite radio station. And you hit the road. Giovanni Circella with our Institute of Transportation Studies researches travel behavior. He’s the one I went to see that rainy day, last December.

Giovanni Circella: Americans love cars. A lot of people love cars, especially when they need to carry something with them or the weather is not very nice like today in Davis it’s raining so a lot of people are using their cars instead of riding bicycles and this is something we need to deal with.

Kat Kerlin: See Amy, you’re not the only one who doesn’t like to get wet. 

Amy Quinton: Yeah, but I need to stop making excuses. Of course, I can’t bike to work because I live so far away. I also don’t own a bike, but that’s not the point. The point is, according to Giovanni, our cities are also really designed for our love of cars.

Giovanni Circella: Cities have been designed in the way that people travel by car to most places. We have residential neighborhoods that were built. And then we had commercial malls that were built in other areas. And then we have offices in central core of cities and in industrial areas.

Amy Quinton: Giovanni told me that it was rational to design cities this way when you think about building our utility infrastructure, separating residential from industrial uses makes sense. But…

Giovanni Circella: But when it comes to transportation, it’s a disaster because it makes all trips longer, it makes many trips not possible to be made with non-car modes and increases the car dependence of society.

Kat Kerlin: Ok, well, we can’t rebuild cities – at least not easily.  

Amy Quinton: No, so perhaps we should just make our cars more efficient. Well, we’ve been doing that. 

Giovanni Circella: Sure, cars are more efficient than they were 10 or 15 years ago but still today we have more miles traveled so the total number of miles is going up and we have more greenhouse gas emissions from transportation. So, we are not on track to achieve the transportation goals that we set.

Kat Kerlin: By goals, I’m assuming he’s talking about California’s climate change goals which aim to reduce greenhouse gases 80 percent from 1990 levels by 2050.

Amy Quinton: Yeah, and one way to get us there is to get more electric vehicles on the road. In fact, our experts say adoption of zero emission vehicles is by far the single most important strategy for reducing carbon emissions from transportation. And by the way, Governor Newsom recently issued an executive order mandating that all new passenger cars sold be zero emission by 2035.

Kat Kerlin: Right, and that’s going to be a heavy lift, given how few people are buying zero emission vehicles now. Lew Fulton is with our Institute of Transportation Studies. 

Lew Fulton: Right now we’re selling at around 8 percent of sales in California, maybe it’s close to 10 percent now, that are electric or hydrogen, zero-emission. By and large those are mostly electric vehicles. 

Amy Quinton:  So Kat, do you own an electric car?

Kat Kerlin: Sadly, no. We’re waiting until our Subaru is on its last wheels. 

Amy Quinton: I don’t either. In fact, I bought a car just last year and the thought of buying an electric car just seemed overwhelming. I think I just assumed they’re really expensive and require charging stations. So instead I just bought a really reliable, fairly inexpensive used one. Apparently, I’m like most consumers.

Dan Sperling: When it comes to buying something big and expensive, people are conservative. With cars and houses, the two largest purchases that people make, they tend to be much more conservative.

Kat Kerlin: That’s Dan Sperling, director of the Institute of Transportation Studies or I-T-S.

Amy Quinton: He says not only are people simply conservative when they buy cars, when it comes to electric cars, people – just like that Uber driver – have an additional anxiety. 

Dan Sperling: There is this range anxiety that exists. The reality is with most of the electric, new electric cars they have quite a bit of range. They range from about 150 to about 350 miles on a charge. So it’s not as much as gasoline, but it’s not like you have to charge it every half hour to get somewhere.

Kat Kerlin: Ok Amy, so say you’re going on a long trip, you would have to charge the car. And in most states, there aren’t enough public charging stations. I think our experts would agree that there need to be more charging stations.

Amy Quinton: Yeah. It’s happening. It does need to happen faster. But the technologies around these cars are changing fast – including longer ranges. Lew Fulton says people are just unaware.

Lew Fulton: I think when people drive electric cars, they are pretty convinced wow, they’re great. They perform really well. But a lot of people have never been behind the wheel of an electric car, so they don’t know that. And incidently, automakers still do not spend much money to advertise these vehicles. They’re producing them. They’re not really marketing them very aggressively. So that has to change.

Amy Quinton: So Kat, I’m one of those consumers who had never been behind the wheel of an electric car or even been a passenger in one.

Kat Kerlin: You were an environment reporter in California. How is that possible?

Amy Quinton: I know, I know. Well, I told Giovanni Circella that. And after our interview, I had him drive me back to Sacramento in an electric car.

Kat Kerlin: Nice. In the name of journalistic research, naturally.

Amy Quinton: Well, of course. I mean, it was also rush hour. It was 5 o’clock. And let’s face it, if I were going to take the bus back to where I could jump on the shuttle bus back to Sacramento, I would miss the shuttle by about 15 minutes. Then I would have to wait until 6 o’clock and I just wanted to get home.

Kat Kerlin: You are full of excuses. 

Amy Quinton: Like most people. 

Kat Kerlin: True.

Amy Quinton: Oh yeah, and it was raining, which I was complaining about, of course, before we even got to the electric car. 

Giovanni Circella: It could rain.

Amy Quinton: I know, oh my God, if it never dropped any precipitation, I would love it. 

Giovanni Circella: Ok

Amy Quinton: Oh, look at this. Alright, research in motion.

Giovanni Circella: Yes.

Amy Quinton: Do you know about this car? Can you talk about it a little bit?

Giovanni Circella: Sure. We can do it. Ok.

Amy Quinton: What kind of car is this? A BMW?

Giovanni Circella: This is a BMW I-3. 

Amy Quinton: That tiny sound was the motor starting. It’s so quiet.

Giovanni Circella: It is nice to be in an electric vehicle. It’s very quiet. We can start driving and we almost don’t realize that we are really going. The car is on, and we’re starting to drive…

Amy Quinton: As we begin our approximately 16-mile journey. We merge onto I-80 and traffic almost immediately brings us to a crawl.

Giovanni Circella: It’s stop and go. We are actually breaking very often sometimes even stopping in the middle of the freeway. It’s very far away from the idea of free flow for which many times we built our interstate system.

Amy Quinton: This was an interesting point. Giovanni says engineers were taught to add more lanes when traffic was not flowing freely. 

Giovanni Circella: It doesn’t work. The more capacity we put on the roadway the more people will travel by car.

Amy Quinton: And the more cars on the road, the longer people sit in traffic, the more greenhouse gases. It’s a vicious cycle. By 5:26, we’re still not in Sacramento. We’re not even in West Sacramento.

Giovanni Circella: The I-80 is a major corridor. The thing that is kind of concerning is that every year it is getting worse.

Amy Quinton: No doubt – but it makes me feel a little better that we are in an electric car. 

Giovanni Circella: The car is telling us right now that we have 67 miles of range remaining. So we pretty much can go for 67 miles without charging, which makes enough for short trips like the one we’re doing. Now of course you know, batteries get depleted. We also have newer cars that actually have better range. But the range is becoming less and less of a concern for most trips.

Amy Quinton: I had no range anxiety. In all honesty, I had looked up where charging stations were near me, and they’re all over the place. We finally arrive at my doorstep.

Ok, so 5:48 so about 45-minute trip for 16 miles. 

Giovanni Circella: Not too bad during peak time. I mean, by Amtrak it would have taken only 20 minutes to go from Davis to Sacramento…

Amy Quinton: Ok, so I should point out that Giovanni – probably like most Europeans – raved about rail systems. But he also says it’s not the total solution for obvious reasons.

Giovanni Circella: But it would have been downtown Davis to downtown Sacramento. And it would have taken a lot more time to go from ITS-Davis where we were to the station in Davis. And then from the station in Sacramento, how do you come here?

Amy Quinton: Yeah.

Giovanni Circella: So we would have probably had to take an Uber or…

Amy Quinton: And so that’s what you think about all the time, from end to end?

Giovanni Circella: Exactly. And that really is what is the biggest difficulty today to change transportation in the U.S. And this is really what we need to think more and more if you want to achieve the climate goals of California because it’s not just electrification that will take us there.

Amy Quinton: Kat, Giovanni thinks about travel from doorstep to destination, end to end. And he says this is where newer technologies like micro-mobility services, those dockless bikes and e-scooters, can help. They can eliminate the need to take a car for short trips, say from rail service to my doorstep.

Kat Kerlin: So micro-mobility will help, electric vehicles will help. So let’s talk about why Giovanni says electrification alone will not allow us to meet our climate goals. Didn’t we say it’s the most important strategy?

Amy Quinton: We did. But electric vehicles still require road infrastructure and still need energy to run. And there’s also the issue of battery waste. And like other cars, they also occupy a lot of space. Did you know? Did you know that a third of the land area of LA is used for parking?

Kat Kerlin: Yikes. OK, so what else do we need to do?   

Amy Quinton: I asked Dan Sperling that.

Dan Sperling: The second big strategy and it’s a much more difficult one, is to reduce vehicle use. 

Amy Quinton: Not easy. But he says the way to do that is to pool or share rides.

Kat Kerlin: By that, he does not mean carpool, right? 

Amy Quinton: Right, Dan says we’ve spent billions on carpool lanes and the number of people that carpool has actually dropped in the last couple of decades. Instead, Dan says the next big step is shared automation. 

Dan Sperling: We need to convert our cars to be automated, our vehicles, and for them to be provided as part of a mobility service where many people would be riding those vehicles and they would give up car ownership. 

Amy Quinton: In many ways, the idea is like Uber Pool or Lyft share – only driverless. Being driverless saves money, so more people can use it, and it makes it way more adoptable for cities.

Kat Kerlin: A study Lew Fulton did a few years ago showed driverless vehicles could lower traffic congestion and greenhouse emissions by 50 percent or more in 2050 if adopted worldwide but, and it’s a big but, they have to be both electric and shared. You can find that on our Science & Climate website at

Amy Quinton: Yeah, and Dan says shared automation is the perfect marriage of mass transit and the comfort of our cars. 

Dan Sperling: They’ll be a computer that organizes the routing and it will just pick up people on your route as you go and it will adjust it automatically. So the net effect is that you have a transportation system that is cheaper, less vehicle use and therefore less greenhouse gases. It requires less road space, less parking, better for equity. So this is really very compelling. 

Kat Kerlin: So UC Davis researchers launched this policy initiative called “3 Revolutions” a few years ago. The main idea being the greatest environmental and public benefit would come from three things: driverless, electric and shared mobility. 

Amy Quinton:  It may sound really futuristic. You know, like the Jetsons cartoon?

Dan Sperling: This is not the Jetsons, this is not pie-in-the-sky this will happen. There’s a big question, how fast it’ll happen and exactly where, but the reality is there is a future that’s a far more sustainable transportation future than what we have now. We’ve mostly failed in transportation. We have a transportation system that’s hugely expensive, huge environmental cost and very inequitable.

Amy Quinton: Kat, since Dan brought up the Jetsons…I did ask him a bit more about what travel could be like in the future. 

Dan Sperling: There are some more exotic things there’s like electric planes that people are developing for relatively short distances, like 50 to 100 miles so you can hop over all that traffic congestions.

Amy Quinton: What? Really?

Dan Sperling: Yeah, there’s billions of dollars going into that right now and eventually they’ll be automated as well. So they’ll be small planes with a few people in them that will fly 50 to 100 miles.

Amy Quinton: That sounds like the Jetsons, I’m sorry, but it does.

Dan Sperling: It does evoke Jetsons. But I’ve given talks at conferences where it just filled up with the engineers and the companies that are doing this.

Amy Quinton: Believe it or not Kat, this idea is really taking off.

Kat Kerlin: Ugh. There you go again with the puns. Oh my. So back to the 3 Revolutions. We’ve got ride sharing, electrification and automation. What is the biggest hurdle to making this low carbon transportation future happen?

Dan Sperling: The hold up or the challenge is: Will people give up car ownership and will they share rides?

Kat Kerlin: And right now, sharing rides is not happening, thanks to a pandemic.

Amy Quinton: I’ll sum it up this way: it’s a disaster.

Kat Kerlin: There’s a negative word.  

Amy Quinton: Well, you know me. But “disaster” is a word our experts used to talk about transportation changes during this pandemic. Ride-hailing, ride share, micro-mobility, and most especially mass transit have seen huge reductions in use.

Kat Kerlin: Yeah, people are using their cars for safety reasons. In fact, Giovanni Circella is currently researching people’s transportation habits during COVID, and he’s found a third of people are using their cars more than they used to and 58 percent remain hesitant to use shared mobility.

Amy Quinton: Probably not surprising, since we saw drive-through graduations and going away parties, drive-through weddings, rock concerts and the return of drive-in movies. When I spoke to Giovanni again this summer, he said micro-mobility use plummeted. People were afraid to touch handlebars of bikes or scooters.

Giovanni Circella: At the same time, micro-mobility is actually experiencing a big, big reduction in use the last few months. Some cities are actually completely banning micro mobility for safety reasons and for social distancing. They’re actually removing all scooters and they actual putting a ban on their use.

Amy Quinton: Those bans have since been lifted, but not without micro-mobility companies taking a huge economic hit. Uber, the parent company of Jump bikes, merged their e-scooter business with Lime bikes as a way to stay alive. But that’s not necessarily a good thing.

Giovanni Circella: This process could continue because many other micro-mobility companies are struggling right now and we could see actually more mergers and acquisitions, which might lead to less competition, less availability of scooters, potentially higher fares and this might actually have an impact in demand.

Amy Quinton: Uber Pool stopped service, at least temporarily. Both Uber and Lyft have seen ridership drop dramatically.

Kat Kerlin: But nothing has been hit harder than mass transit. When COVID-19 first hit, public transit in San Francisco and New York saw a 90 percent decline in ridership – 90 percent! Here in Sacramento, Sac RT has seen ridership drop 70 percent, although there has been an uptick since then.

Amy Quinton: And that’s particularly concerning because in lots of cities, transit was already in trouble. Dan Sperling says those services rely on government funding and subsidies.

Dan Sperling: The government doesn’t have a lot of money right now. Tax revenues are down and costs are way up. So there has to be a reckoning. I think some of the smaller transit operators. They’re probably going to disappear.

Kat Kerlin: That is not good. So could this all return to normal once the pandemic ends?

Amy Quinton: Well that’s a good question. And it’s something Giovanni is researching.

Giovanni Circella: Certainly the pandemic poses a question about even if we go back to normality, what the future of transportation will look like. This has been a question already for many people that rely on public transportation because they don’t have other ways to move around. And so some are actually reported to be buying a car. 

Amy Quinton: Yep, more cars on the road.

Kat Kerlin: At least for those that can afford to buy one. There is a huge equity component to all of this. The drop off in transit use is going to affect the lower income and disadvantaged people the most. 

Amy Quinton: Just like with so many aspects of climate change. But maybe the pandemic will make companies more open to the idea of telecommuting. And maybe video conferencing with your doctor won’t be such a weird thing anymore. And Dan believes ride sharing will pick up again – it’s just a matter of when. 

Kat Kerlin: You can learn more about our transportation research on our Science and Climate website,

Amy Quinton: And listen to more episodes of Unfold at I’m Amy Quinton.

Kat Kerlin: And I’m Kat Kerlin. Thanks for listening.

Credits: Unfold is a production of UC Davis. It's produced by Cody Drabble. Original music for Unfold comes from UC Davis alumnus Damian Verrett and Curtis Jerome Haynes.