The first movie's message was "Nuclear wars are bad, shape up or die".
The second movie's message was "Environmental mis-management is bad, shape up or die".
Both statements are true, both messages are pertinent. Unfortunately, where the first film left the implementation of the lesson to the imagination of the watcher, and thus was a moral and intellectual challenge, the second film introduces a deux ex machina where all technology ceases to work.
This is unsatisfying morally, intellectually, and artistically. Morally, because it places the blame on technology rather than human greed, intellectually because the "answer" is supplied externally rather than something the watcher has to think through, and creatively because it is simplistic.
It is also morally and intellectually wrong, morally because technology is morally neutral, it is human choices which are good or bad, and intellectually, because the level of technology that is "bad" is not specified. Does humanity have to go back to the trees for example? Or simply to a pre industrial technology? Or to something in between - the neolithic perhaps?
This film is yet another example of the creative vacuousness of much contemporary cinema.
Jon