The problem with these scenarios is the fact that there are natural cycles going on all of the time, but, since we have not recorded them since the beginning of time, we are unaware of long-term cycles affecting changing land masses and weather.
Volcanoes spew forth all kinds of 'stuff' on a regular basis. These activities replenish the earth. The Sahara desert expands and contracts over the decades. Nature is not static!
How comforting it is that panic-mongers are creating a huge disaster in the area of human health (as if the medical mafia, their friends and our own bad habits have not already done a great job!) for the next ?? years in the name of saving the planet! By the sound of it, for whom?? From their own narrow view that technology rules, the majority will pay the price!
It is my personal contention that if we could all spread out a bit and each have a decent property on which to grow our own food, we could all stop running around supporting the 'economy'.
Unless one is part of the super rich, we are all pretty much peasants in our mud huts!! :) It is bigger or smaller, but we have no real power. (We'd have to keep the internet, though!)
Nature strives for balance. Nature does not strike a balance for people -- the people must work with Nature. We are to be guardians of this planet, not dictators.
I am certainly no scientist, but I don't believe that man's relatively short stay on this planet has had such a dire impact. There are two sides to every story but we are fed the panic monger's side every time.