I have been away for a few weeks, traveling to the Waterkeeper Alliance annual conference in Wilmington, NC and then floating a river with some Waterkeeper friends afterwards. I took the Amtrak train to Wilmington, feeling all hair shirted righteous about all the greenhouse gas impacts I was avoiding by riding the green rails for 12 hours instead of those nasty, carbon spewing airplanes for two.

EXCEPT . . . whenever I try and poke around to get the real truth about the carbon impacts of rail travel and tote up the numbers for my personal carbon budget . . .  all of my illusions are shattered and I get reminded that the only kind of long distance travel that is really sustainable is ocean sailing, or bicycling, or maybe packed into an intercity bus, or three people on a road trip in a Prius.

Here’s the problem: a 2008 Union of Concerned Scientists report on CO2 impacts of travel calculates Amtrak’s GHG impacts at about .37 lbs/passenger mile for the electrified NE Corridor, or about .45 lbs/passenger mile for the rest of the rail network.  That is actually not much better than flying.  Amtrak’s own website is now coy on the subject, stating only that the GHG impacts of rail travel are “less per passenger mile than either cars or airplanes.”

But . . . how much less?  When I work out my train trip to Wilmington using the UCS numbers, I get a total of 209 pounds of CO2, or about .1 ton of CO2. I ended up flying back from Charlotte, NC after our river trip (had to teach my class Thursday afternoon).  When I plug that flight into, it shows a CO2 emissions of .12 metric tons of CO2, or about .13 English tons of CO2.  So taking the train might only about 25% better than flying. And lots of long distance travel by train OR plane is not ever going to be consistent with a sustainable carbon footprint.

Things get even more complicated though, since air travel involves greenhouse impacts beyond just those caused by burning fuel — there’s water vapor and nitrogen oxides at altitude, which have potent greenhouse gas effects. Some studies suggest that the true air travel GHG impacts are double those implied based on fuel use — as much as 500 grams per passenger mile, or about one pound per passenger mile.  Amtrak would then be only half the emissions of flying.

Of course, if I want to feel good about my train travel impact, I can always just plug my rail miles into the calculator – they come up with just .01 metric tons for the same train trip, less than one tenth of the return flight.  Who should I believe, the Union of Concerned Scientists, or


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