Perhaps no single area is impacted

Perhaps no single area is impacted more by transport
than the environment. Every sector of the natural
environment (water, vegetation, geomorphology, soils,
animal life, and the atmosphere) receives negative
impacts from various transport systems. In some cases
there is little knowledge about the scope of these
impacts, e.g. the impacts of transport on the movement
or fatalities of animal populations. However, it should
be apparent that the atmosphere is currently receiving
the major negative externalities at this time. There are
four major problem areas: urban air quality, ozone
depletion, acid precipitation, and global warming.