There once was a time where the world was a peaceful place full of nature and balance, then came humans. We are clear cutting entire forests, strip mining out the land, causing countless species to go extinct, polluting everywhere in every way, the world is a fabulous place but it simply cannot sustain humans for much longer. Don't believe me research for yourself.
In recent years technological, weaponry and scientific discoveries have made the world what some would say a better place, but these advancements are now foreshadowing the destruction of humanity. Many believe that a nuclear war will be our end and this seems entirely legitimate. Nuclear weaponry has vastly - and is still vastly developing, and although it provides energy and greater prospects into the study of science and the universe, it also poses one of the greatest threats on this planet. The current North Korean crisis is a prime example of this. Leader Kim Jung Il has allegedly considered the prospect of nuclear warfare to 'better' his nation and seat of power. Whether good or not, this is debatable, but the fact remains that humans have developed to many forms of their own destruction and that this will be their own eventual downfall.
Until and unless the world is not sure about any other existence in outer space, we cant hold humans accountable for destroying thee world. And who knows that may be the world gets hit by a meteor. The debate will always revolve around without and resolution but both the sides hold same amount of sources and reasons.