Transportation can be a big culprit when it comes to climate change. So what’s the best way for Minnesotans to reduce their transportation carbon footprint? It’s probably walking or bicycling, even though exercise makes you exhale more carbon dioxide, the chief greenhouse gas linked to global warming.
However, when it comes to the way most of us travel, conservatives have expended a lot of energy lately trying to show that private cars and maybe even big SUVs are no worse for the environment than public transit. While that premise is largely false, there are a few cases when it’s actually true.
Take ferry boats, for example. Across the United States, they emit nearly three times as much CO2 per passenger-mile as the average automobile while the hybrid gasoline-electric Toyota Prius has a carbon footprint barely half the nationwide transit average.
These comparisons, based on federal energy consumption and emissions data, come courtesy of Randal O’Toole, a senior fellow at the libertarian Cato Institute and author of “The Best-Laid Plans: How Government Planning Harms Your Quality of Life, Your Pocketbook and Your Future.”
“Far from protecting the environment, most rail transit lines use more energy per passenger mile, and many generate more greenhouse gases, than the average passenger automobile,” O’Toole wrote in April 2008. He suggested that the United States abandon all rail transit development and concentrate instead on putting more hybrid, biofuel and electric buses on the streets and building new congestion-priced toll roads.
His own figures, however, take most of the steam out of his argument. Motor buses, which comprise most of the U.S. transit fleet, are worse than even SUVs and pickup trucks in carbon emissions per passenger-mile. Light rail beats all three, with about half their carbon footprint. Commuter rail, subways and trolleys are even better.
Here are O’Toole’s numbers:
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This sure looks like a clear win for rail transit. In the face of this inconvenient truth, O’Toole argues 1) that new federal fuel-efficiency standards (Prius-izing the entire U.S. fleet) will eventually make cars more earth-friendly than transit, and 2) that energy used to build rail lines far exceeds the savings from their operation. He dismisses the energy costs of street and highway construction with no supporting data, simply on grounds of their higher traffic loads.
But a new study by University of California-Berkeley researchers Mikhail Chester and Arpad Horvath attempts to quantify all the environmental costs of the various transportation modes. They show that there’s much more to it than simply counting up propulsion inputs and emissions. They call their approach environmental life-cycle assessment.
For cars, light trucks and buses, in addition to operating emissions, they considered the greenhouse effects of herbicides and salting along right-of-way; road construction and maintenance; automotive repair and maintenance; vehicle, fuel and tire production; parking and roadway lighting. For rail transit, they looked at track and station construction and maintenance; rolling stock manufacture; station parking, lighting and escalators; even heating and cooling. No doubt smart people will unearth even more relevant factors.
By Chester and Horvath’s calculations, the big environmental winner is the bus, but only at fully loaded peak-hour operation, with about 80 grams of carbon dioxide emitted per passenger-mile. The big loser is also the bus, at sparsely patronized off-peak hours, with 630 grams emitted.
In between are sedans (360 grams per passenger mile), SUVs (430 grams) and pickup trucks (500 grams, a little over a pound). Chester and Horvath worked up comparable figures for four rail services in California and Boston’s light rail Green Line. The worst of that lot was the Green Line, emitting 225 grams per passenger-mile, a figure the researchers said was inflated by the fossil-fuel-intensive character of its electric power supply. Bay Area Rapid Transit (BART) and Caltrains both came in at a hair over 150 grams.
In the future, as electricity production shifts away from coal and other fossil fuels to greenhouse-neutral wind, hydroelectric and perhaps nuclear power, rail transit’s carbon footprint is bound to shrink, possibly even faster than that of private automobiles.
As Minnesota nears final federal approval of the Central Corridor light rail line and begins planning additional urban transit and intercity rail routes, it’s important to focus attention on all the facts about transportation’s effects on the environment, and not merely spin that’s driven by ideology.