From Jared Diamond’s Collapse: How Societies Choose to Fail or Succeed:

…the world’s environmental problems will get resolved, in one way or another, within the lifetimes of the children and young adults alive today.  The only question is whether they will become resolved in pleasant ways of our own choice, or in unpleasant ways not of our choice, such as warfare, genocide, starvation, disease epidemics, and collapses of societies.  While all of those grim phenomena have been endemic to humanity throughout our history, their frequency increases with environmental degredation, population pressure, and the resulting poverty and political instability.