The problem that been outlined by some world leading authorities, namely Dr. Hawkings amongst many others, is a lack of predators that rely on the homo sapiens species..  We are allowed to run amok, savaging the planet for our own personal gain.  In the natural world, the millions of species are kept in check by a sophisticated system that evolved over billions of years.
It is only the past few hundred years that this balance that has taken so long to evolve , is interrupted by the onslaught of the human race.
Only we, or a superiour presense can save the planet now.  

We are in the midst of the 6th great extinction, and has been exasperated by human activities