Correct me if I'm wrong, but are we not now, reading this, sitting in a civilization with greater capacity for resource production and allocation, longer average lives, and better systems of healthcare than all of the previous cultures this study brings up?
Are we not also aware that any mathematical model of consumption for any growing civilization at any period -- easily predicts resources running out and impending catastrophe? Do we not note that priests and others have been predicting the end of mankind for as far back as we have written history? Can we not observe that all cellular-based automata modeling systems default to runaway conditions? Is any of this some kind of mystery?
There may be real danger on the horizon -- creating some kind of human super-organism on the planet creates a single point of failure, and that's extremely bad -- but I remain convinced that when the world does end, there's going to be a lot of disappointed people out there that it did not end the way they thought it would.
"Scientists" are folks who tell us the likelihood of causality. You do A, B is likely to happen. They do this through falsifiable theories and reproducible science. They do not spend time and money with broad speculations about the ills of human nature, and how those ills will conspire bring about our punishment. I don't know what that is, sounds like religion to me, but it sure ain't science.