Destroy the supply chain. It’s surprisingly fragile, and if it fell over it might even be impossible to rebuild. For instance, energy production has a whole bunch of dependencies on mining, which requires large amounts of energy - and all the infrastructure requires constant maintenance, which requires all the infrastructure.

One swift kick in the nadgers and the whole system goes down in a tangled heap, with all your tools at the bottom.

Large-scale industry would be crippled out of existence for a very long time, possibly forever - and maybe the oceans wouldn’t end up boiling.

There are plenty of chokepoints in the system, where a small disruption could have disastrous effects. Just look what one ship screwed up by getting temporarily stuck in a canal for a couple of weeks. If a nation or two set their mind to it, they could throw a spanner or three in the works that would rip the whole engine apart.

The human cost would be utterly devastating, of course. Billions would die, and the knock-on effects would just accelerate the decline.

But the way things are going, they’re all going to die anyway, and take the rest of the planet down with them. This way seems less-worse, and we get to play The Last Of Us irl.