Hi Umbra,

I’m wondering if you have any numbers comparing the fuel efficiency of flying versus driving the average car for the same distance. Also, how does carbon dioxide production compare for the same trip?

Loomis, Calif.

Dearest Steve,

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Flight blight?

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Here’s what I can find so far, courtesy of the Rocky Mountain Institute in beautiful Snowmass, Colo. Single-occupancy automobiles produce 0.91 pounds of carbon dioxide per mile. (You can do the long division to figure out the per-person impact if more people are traveling.) Commercial aircrafts, meanwhile, produce 0.57 pounds of CO2 per person per mile. However, planes emit gobs of other pollutants at high altitudes, particularly our smoggy friends the nitrogen oxides, which may almost triple the climate impact of plane travel. Little is known about the effects of atmospheric releases of NOx. I’m sure it’s making us healthier, just as biotechnology will end world hunger.

As you know, the pollution impact of every plane trip includes your travel to and from the airport, all the little golf carts zipping around on the tarmac, and the thousands of airline employees who go to work to get you on the plane. These other “mobile sources” must be factored into the per-mile pollution burden of air travel, and RMI appears to be working on it.

I’m going to carry on looking into fuel efficiency for you, and perhaps educated readers will care to contribute their knowledge. (You may also want to check out this Grist piece on the subject.) Jet fuel and car fuel are somewhat different substances, so there may not be a simple, direct correlation.