Weirdly, the nuclear era has made a third world war less likely. Mutually assured destruction kept the Cold War to mostly proxy nations instead of an all out worldwide theater like occurred over the prior 300 years (going back to the Spanish vs. British vs. French in the colonial age).

Meanwhile, I suppose a super volcano or a shift to ice age temps would be disastrous for the environment and crop yields, but technology would be our only recourse for dealing with it and adapting to it.

I'll admit, there's trade-offs to modern tech. It's definitely a double-edged sword, and I'm not sure our physiological systems are well-tuned for modern society (i.e. hunting and gathering guaranteed an active lifestyle). But overall, I think it's a positive.