Sorry, but "massively changing the human environment" has been happening since people started building houses and wearing clothes - and generally doing things to change their environment for the better.
The species will evolve and adapt over time and thrive in whatever environment we create for ourselves. (on Earth, Mars, wherever)
Relax, and remove your tinfoil hat. The "good ol days" weren't so hot and I look forward to a new and better human being.