As more and more people around the world can suddenly afford cars, transportation has become the fastest-growing source of carbon pollution in the world. But a new study explains how that can turn around: If the world’s large cities make a serious effort to improve public transportation, we could collectively save $100 trillion and cut emissions from urban transit by 40 percent by 2050.
It seems intuitive that better public transportation would reduce pollution. But this is the first study to look at exactly how much it could help. In the past, carbon policy has often looked at another part of the problem–how we can shift to renewable energy. This study wanted to change that emphasis.
“There’s been far less focus on how changing the way we design, build, and operate cities can influence the long term demand for energy,” says Michael Repogle, policy director at ITDP, a group that co-authored the report. “What we find when we reframe the question like that is that there are vast savings that can be achieved.”
The study looked at two possibilities for the year 2050–what would happen if cities continue with business as usual, and what would happen if they start to follow some of the most transit-friendly cities today, like Copenhagen or Tokyo. The researchers were especially interested in developing countries like China, where carbon pollution from transportation is expected to balloon by about 600 percent if nothing changes.
“The biggest growth that’s going to occur in urban populations over the next several decades is in the developing economies of the world, and they have yet to make their investments that will be needed to support urban growth,” Repogle says. “If they develop their transit closer to what we see in countries with good public transit, it makes a vast difference in the demand for energy.”
It makes an equally important difference in more developed countries–which Repogle points out are also quickly changing. “In the U.S., for example, two-thirds of the buildings that will be in place in 2030 haven’t been built yet, because we tend to renew our building stock over time. If we invest more in public transportation and make it easy to walk and bike to transit stops, then we can build around that system, and drastically cut the number of miles that we drive every year.”
Beyond helping the climate and saving trillions of dollars, the changes could also help reduce inequality. For the poorest city residents, better public transportation could increase travel by 300 percent, making it easier to get to work or school.
“That’s a huge difference in the ability of the world to deliver a promise of a path for inclusive growth that helps those who are now trapped at the bottom of our social and economic structure, so that they can find a way into access to education and health care, decent housing, and a good life,” Repogle says.
The changes needed are far-reaching–much better rapid transit, better bike lanes and pedestrian networks, and tighter emission standards for buses and cars. But the researchers are optimistic that cities can make the shift. “I think we see city leaders coming together to make commitments in this direction,” says Repogle, who was at the UN climate summit when we spoke, where hundreds of cities made commitments to reduce climate emissions by 13 gigatons by 2050.
“If we don’t take action the greenhouse gas emissions from transportation are forecast to increase by at least 70 percent,” he adds. “But if we take the kinds of actions described in the study, we can cut those emissions significantly below their current levels and make a huge difference for our future environment and the quality of life in our cities.”