I'm pretty worried about this as well - esp. about heatwaves, but I don't think that would result in nuclear war in our lifetimes. Unless China messes around with rivers that originate in Tibet that is.

Possibly my biggest worry is water - providing water for 1bn+ people (and agriculture, and industries) is going to get harder and harder. I'm a techno optimist, so I'm hoping some variant of desalination tech will pull through if things get really bad.

The other big worry as you say is the heat waves. If we do get emissions under control, I think we'll also end up doing some form of carbon scrubbing and don't just sit around in a 2C warmer world. None of our current climate engineering approaches are enough to arrest global warming by themselves but I'm hoping we can eventually control the amount of CO2 in the atmosphere.