While older coal trains would have stayed more locally, modern ones go all over the country, so check out your era and make decisions accordingly. There is a book from Kalmbach about coal railroading. Modern trains from Powder River end up as far as Florida, I think. That is because that coal is low-sulfur, other coal is not. Stricter EPA reguilations a while back shifted where coal came from. Sadly the EPA isn't doing too well combatting CO2 emissions.
We know temperatures from the last 650,000 years or so from ice. We can also tell the CO2 concentrations in the air from that ice, and it shows a clear corrolation between temperature and CO2. And there is a lot more CO2 in the air than there has been for the last 650,000 years. Why? Because of oil, gas, and coal. Global warming is a FACT, not a theory. What it will do to the earth and humans in the future is a theory, although we know pretty well that if CO2 emissions continue uncontrolled, what happens to the earth and humans will not be good, we're just not sure how bad.
Those scientists evidently lost their reputation pretty quickly when they said global warming doesn't exist. They probably got rich too, Exxon-Mobil has a lot of dough. Only in the past few years has a scientific consensus been reached about human-caused global warming, although research has been going on for a long time.
The ozone layer was NOT crying wolf, it was a serious problem that was pretty much solved by countries stopping the use and manufacture of CFCs. We need to apply that same legal and political might/ will to global warming and gradually phase out fossil fuels over the next 50 years or so.
Educate yourself about the real science of a topic like global warming before you post uneducated comments that are not based in any fact. There is a great article on wikipedia about global warming. It is very neutral and scientific, and presents various parts to global warming. It also has a nice chart that shows how CO2 levels went up around the industrial revolution, and the corresponding temperature change.