Think twice about 'green' transport, say scientists

Agence France-Presse

PARIS (AFP) – You worry a lot about the environment and do everything you can to reduce your carbon footprint -- the emissions of greenhouse gases that drive dangerous climate change.

So you always prefer to take the train or the bus rather than a plane, and avoid using a car whenever you can, faithful to the belief that this inflicts less harm to the planet.

Well, there could be a nasty surprise in store for you, for taking public transport may not be as green as you automatically think, says a new US study.

Its authors point out an array of factors that are often unknown to the public.

These are hidden or displaced emissions that ramp up the simple "tailpipe" tally, which is based on how much carbon is spewed out by the fossil fuels used to make a trip.

Environmental engineers Mikhail Chester and Arpad Horvath at the University of California at Davis say that when these costs are included, a more complex and challenging picture emerges.

In some circumstances, for instance, it could be more eco-friendly to drive into a city -- even in an SUV, the bete noire of green groups -- rather than take a suburban train. It depends on seat occupancy and the underlying carbon cost of the mode of transport... [snip]

It used 2005 models of the Toyota Camry saloon, Chevrolet Trailblazer SUV and Ford F-150 to calibrate automobile performance; the light transit systems in the San Francisco Bay Area and Boston as the models for the metro and commuter lines...

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