To be honest, I think it is fairly unpredictable what will happen with stock values if there is strong global warming. And if government breaks down having anything might not be worth much unless you have an army to defend it.
In the long run, equities have always outperformed real estate, regardless of climate or weather events: companies and peoples can move, pieces of land cannot. And 'Mad Max' scenarios are currently not projected to happen anytime remotely soon if ever.
To be fair, 'Mad Max' isn't something you project, it's an overly optimistic post-script to a total nuclear exchange. It may be that pressure from climate change and poor coping mechanisms on an international scale could lead to said nuclear exchange, although I certainly hope not.