Photo: Bei Piao/Imaginechina/Corbis

It’s hard to talk about the long-term perils of driving without sounding like a wild-eyed freshman who just discovered environmentalism: It fills our atmosphere with harmful greenhouse gases! It destroys the layouts of cities and creates sprawling suburbs! Energy-wise, it’s an incredibly inefficient way to travel! The problem is, these are all true statements, and a new report from UC Davis and the Institute for Transportation Development and Policy highlights just how screwed humanity might be if we can’t curb our collective driving addiction.

Well, technically it looks at things form a more optimistic perspective — what will happen if the world can collectively get its act together and nudge people away from driving.

Assuming a worldwide effort to “expand[] public transportation, walking and cycling in cities” — a big “if” — the world could benefit to the tune of:

• “1.4 million early deaths associated with exposure to vehicle tailpipe emissions … avoided annually by 2050”

• more than $100 trillion in savings between now and 2050

• 1,700 megatons per year of reduced CO2 emissions

None of this is going to come out of the good of individual people’s hearts — with the exception of a few saintly types who are willing to endure a much longer commute even though it would be easier to drive, people tend to make these decisions on the basis of convenience. In New York, for example, parking is impossible and mass transit coverage is pretty good in most neighborhoods; New Yorkers take the subway to work not because they are more environmentally conscious than denizens of other cities, but because it makes sense for them as individuals. So it’s up to governments to change the incentives to get people on mass transit, bikes, or whatever else. A lot is at stake.