1. Unsustainable population growth is self-correcting.
2. If you claim the question of whether we are affecting the environment for better or worse, is open ended - that is, we have to see the results to answer the question -- isn't proof of a mistaken assessment of results grounds to change the answer? Since part of the assessment was, We are doing Bad to the Environment because we are killing arctic life like polar bears, if in fact we are not destroying the species, isn't it time to revisit the assessment?