Sorry, but your first sentence is bogus. I deal in facts: disease and starvation (malnutrition is still here, however) are all-but eliminated compared to former times. War deaths are a small fraction of what they were pre-1960. These are golden times, my friend: enjoy. 
Projecting devastation and apocalyptic visions are meaningless exercises. History is rife with such nonsense: human ingenuity always has found a way through with science leading the way. Global warming, our greatest challenge, has technical solutions, but they're not economically feasible, in today's political climate. 
Almost 8 billion humans now inhabit this planet. If that is too many, please feel free to lighten the load... More seriously, planting trees, eating vegetarian, having zero children, and living in metro areas are the best things a person can do.