How about some hypothetical technology that can scan space for nuclear weapons and destroy them from a distance even if stored within thick walls of lead and without leaving a trace?

That would be delightful, but as I read it the question was about a weapon singlehandedly rendering nukes irrelevant by its own destructive potential, not in tandem with an otherwise pretty low-damage nuke-nullifier that happens to be invented around the same time. Unless your idea of "destroy them" is to actually detonate your enemy's own nukes in their bunkers... well, that's still a hard sell for "surpassing", since you're either using the nukes after all or just convincing your enemy to take them off the table.

Surpass in destructive power doesn’t mean much since we can already destroy all life on the planet with nukes. That’s what makes the doomsday weapon in Dr. Strangelove so ironic and funny. But if a new weapon type that at least approximates nukes in destructive power while also surpassing them in ease of proliferation, cost of production, or detectability? Those are much scarier propositions.

Nukes are several orders of magnitude away from destroying all life on this planet.

https://youtu.be/JyECrGp-Sw8

It’s a distinction without a difference. For human purposes, nukes can effectively destroy us completely. We don’t need to also physically rip the planet apart and destroy all the single celled organisms to ruin the planet for ourselves.

The nukes that actually exist today would reduce us to a medieval or early industrial existence, except with a lot of information about how to rebuild faster — Hiroshima and Nagasaki both got rebuilt and are now thriving, and while modern weapons are higher yield and much of the industry to rebuild with would be destroyed, not all of it would be, and roughly half the global population would still be alive to do it.

I wouldn’t count that as “effectively destroy us completely”, even though it would be really bad.

Keep in mind that all the easily-mined coal, oil, and gas deposits have been used.

We might be kinda screwed if something takes out civilization (e.g., the nukes fly).

I guess we can hope that nuclear winter is exaggerated or non-existent and the southern hemisphere pulls through with intact infrastructure after the exchange.

Sure, everything would suck for a while[0]. But we had wind and hydro for a long time before electricity and steam, so those that survive could rebuild, analogously as to how we are presently weaning ourselves off fossil fuels without such destruction.

[0] I realise given the context of global thermonuclear war this may seem like understatement. Well, I’m British and I have a stereotype to uphold.

It might not be as easy as you'd hope to rebuild.

This essay does a good job of explaining why it's probably possible in principle and why in practice it might be quite difficult:

https://aeon.co/essays/could-we-reboot-a-modern-civilisation...

(Incidentally, I highly recommend that author's book _ The Knowledge_, which is a more extended meditation on industrial civilisation and what it would take to reinvent it if we lost it.)