Don't say it can't happen, because those in the know have seen the kind of radical weather alteration experiments that have been conducted secretly in recent years, or at least speculated as to them being carried out.
The article, which can be found by going to http://www.naturalnews.com/026021.html and scrolling down, suggests that someone could bury an unseen nuke under the surface and when the top erupts, blame it on some sort of natural event.
While that seems far-fetched, the importance of this article is that you can't rule anything out when dealing with the people that run things nowadays. They have proven time and time again they have no problems "playing God" for their own interests and ignoring the health, needs, and safety of the general public.
Of course, such a plan isn't likely to happen but a plan to for "global dimming" has at least been discussed at some level and is obviously another example of the "magic bullet" theories of modern society whereby people attempt outlandish solutions to complex problems as a means of taking a shortcut to solve problems that could have been fixed with preventive, prudent measures instead. Keep an eye on the "global dimming" phenomenon and let's make sure it never happens unless as an absolute last resort (maybe....