[gedy]

A parent - and raise your child(ren) to live in an ecologically sensitive manner that you wish the rest of the world to be. (Am being honest, not being snarky)

[azangru]

Surely not being a parent is friendlier to the environment :-)

[gedy]

Not if those who care about the environment are replaced by those who do not care after a generation or two.

[notduncansmith]

I believe so on average, but for individuals it depends on the impact your kids have :-)