We have been talking about ecological stuff in my sociology class and my teacher told us about this US government project, HAARP, that is potentially extremely harmful to the earth. I thought it was interesting because they (the Pentagon) say that it is a great communication device while the environmentalists like to point out that it is potentially a weapon because it subjects the earth to direct sun rays by blasting holes in the ionosphere.
Here's their website:
http://www.haarp.alaska.edu