NoMyth is a funny name for someone perpetrating falsehoods. A 747 jet has a bigger carbon footprint than a steam locomotive could EVER have. I wonder how many 747s there are operating every minute?
Locomotive "emissions" played absolutely no role in the demise of steam power -- it was the lower maintenance, fuel price, and smaller workforce required to sustain diesel operations. A locomotive fired properly burns its carbon fuel, instead of "emitting" it.
Maybe these trains'll do some good in the way of public unfamiliarity and ignorance, since their operation will be primarily to educate. I say all aboard.