Inside the KH,
You are correct. They have widened the scope of what disasters await the planet. However, it is THE BULLETIN OF ATOMIC SCIENTISTS. The ecological problems are probably included to create some buzz. In a way "nuclear winter" from a hundred or so city busting bombs would probably solve the "global warming" problem. The reason nuclear weapons are so serious is that you can't stop the process. The events that could cascade into a nuclear conflict are rooted in fear. Fear means emergency. Emergency requires a rapid response. It could be all over in less than an hour. The two entities that have the fire power to bring this about- Russia and the USA are now in a state of serious confrontation. This current confrontation emerged in a world that thought it had reached the end of history.
The point I want to make is that without some kind of "sky-hook" we're all doomed as a species. There is no reason to believe that humans are going to change course. Territoriality runs very deep. We are of the same world as the animals. The world of humans that has naturally organized itself around it's greed for pleasure, comfort, and unbridled power is flawed and it can't reorganize itself. The world has to experience the consequences of this course right up to the brink of total annihilation.
It will take just such a cataclysmic failure to dispose humans to try a new and different approach. We learn from experience. What we experience is - failure. This process is what the Bible means when it speaks about the end. The end of an ego driven world. The beginning of a world based on the basic requirements for living. If there isn't something bigger than us we are hopeless. The Bible speaks of a Kingdom of the Heavens. It remains to be seen what entities actually make up the "sky kingdom". We need something even non-believers can believe in.