Anyone who has any doubts about the impacts of human beings on our dynamic planet's natural systems, should spend just a few minutes on Google Maps (or Google Earth)...
Start here:
http://maps.google.com.au/maps - then zoom in a few times, around major population centres and regional, rural and outback places alike...
Once you've had a broad overview of each of these areas, zoom further and further in - to the point where the patterns of man-made geometry dominate over the natural topography...
One thing that you will notice, is that most of the native East Coast vegetation has been decimated but that there are still pockets of dense forest - albeit juxtaposed to monocultures, housing developments, industrial precincts and quarries...
Start at Queensland, move through NSW and then focus for a while on Victoria and SA - especially those areas which are at the tail-end of the now-toxic Murray Darling system...
Then move over to WA and back up to the NT...
Be sure to dwell on the scars on the landscape over the 100 to 200-odd km radius around where you currently live...This incredible amount of damage has been done in less than 250 years by a measly population which has not long risen above 20 million...
Now imagine that repeated across the globe - especially in the more densely-populated so-called 'Western World' - but also in those other places which have become the defacto quarries, foodbowls and factories that provide so much to material 'junk' to support the obscene lifestyles of the individualistic peoples who wantonly consume 20-30 times their fair share of the world's resources...at the enormous expense of current and future generations...