*digesting the import of Amos' post*

..seems to me the core of that is the phrase 'tends to adjust' , which I'd have have some examples of to judge.

but also, those molecules you mention are not insignificant...the notion of 'total bio-mass' comes into play very quickly when very large populations (and this includes animal & plant populations) try to co-exist. Ethiopia is a small scale example.

" But I don't think we are anywhere near pushing ourselves off the edge of the planet" ...but we sure ought to have some idea of HOW close, hmmmmm?