Trucking around firewood from where you live to your campsite wastes money and creates excess CO2 outfit — at least, according to The Nature Conservancy. As part of their "Don't Move Firewood Campaign" (itself an outgrowth of the heady-sounding Continental Dialogue on Non-Native Forest Insects and Diseases), you can calculate exactly how much of a bad person you are by plugging your car's gas mileage, the number of firewood pieces you're bringing, and the distance to your camping destination into this firewood calculator.
There's only one small problem: Unless you're carting enormous amounts of wood over vast distances in cars with terrible gas mileage, it doesn't seem like you're losing too much money or putting out that much carbon. Even if we go generous, and take 50 pieces of firewood 100 miles in a gas guzzler that gets 15 to the gallon, we only lose $2.64 and put 13.19 pounds of CO2 into the atmosphere. No one likes to lose money or put any extra pollution into the air, but the result is hardly catastrophic.
Of course, add it up over cumulative weekends, and maybe they have point. But their primary argument is a much more convincing one: Moving firewood brings invasive pests and insects to new forests, causing those forests to die out and catch on fire. Witness the infernal hell that is California if you need proof.