As always, human nature will make it impossible to solve these issues. We all try to blame so many other entities for all our problems, but it's us. We (as a whole species) are the only mechanism powerful enough to make actual fundamental change. Everything else pales in comparison. And, yah!, we are the mechanism that is basically impossible to actually get pointed in the a particular direction.
It can happen, but it takes enormously ugly events to do it, like WWII. And of course, eventually our human nature will insure that the enormously ugly event happens, but it may be too late at that point. And people generally don't think about it so much, but a huge die off in the human population will have devastating consequences as well, and not just for the people who die. We would be very hard pressed to maintain our technical society if that occurred.
So the only actual solution: an immediate, non-extremist but very broad change in direction, sustained over decades and centuries, is the one almost certainly never to happen. It will probably either be that we reach some tipping point and have a massive collapse with a centuries long recovery, or we just breeze right past the point of no return and figure might as well party since the end is coming anyway.
There's a slight chance that science might save us, at least from the worst of it. Though that may just be putting off the cure until the cancer is orders of magnitude larger, who knows.
