There are several environmental issues that are important. The first one is that you can use alternative fuels, and they don't burn much fuel to begin with, so they should not emit much carbon.
It's quite conceivable to have an airship that would be fueled on hydrogen, because the gas tank is not an issue. They're very, very big already. So air pollution would be one issue.
The second one of course is this issue of building roads through virgin territories and what it does to the wildlife in those areas, and what kind of protest you get from the people who don't want to see you building through a park or natural area or the aboriginal land claims that are existing.
As well, once you punch a road through an area you create an opportunity for predators to move along those arteries—whether they be four-legged or two-legged—and the caribou get affected. We have threatened species where there are plans to build roads right now, and this is a restriction on them.
There are major environmental issues.