One of the challenges with complex systems is that understanding of the problem and solution co-evolve – you can't determine root causes, you can't identify all the variables that affect the outcomes, and you can't predict what will happen. That makes it hard to 'solve' problems like global warming, world poverty, violence, corporatism, unaffordable health care and dysfunctional education systems.
What makes it even harder is that we often don't know what we need – what the 'future state' would look like if we 'solved' the problem. When it comes to global warming, for example, some see the ideal future as one of strict conservation, while others see it as one of miraculous new technologies that allow energy consumption to increase forever. It's hard to figure out how to get there when you can't even agree on the destination.