It used to be, at the beginning of the 80s, dystopia was dark, rainy place:

Or a dark radioactive place:

These days it seems like it's going the other way. Dystopia is hot, arid place where water is at a premium. For example Dredd:


Or Elysium:


Is this just a Hollywood acknowledgement and simplification of global warming? Or just advances in CG and digital mattes?