It is hard to destroy the planet even with nuclear weapons. A full-scale nuclear exchange will probably put humans back in the stone age, but the species will p

It is hard to destroy the planet even with nuclear weapons. A full-scale nuclear exchange will probably put humans back in the stone age, but the species will probably survive (billions will die, the life will be awful, of course, and it will take thousands of years for the civilization to recover, but humans will survive). With some deliberation, it is possible to destroy all complex land-based lifeforms (with radiation weapons / cobalt bombs, and you need _a lot_ of them, like a planet-scale suicidal project, I don’t think it is possible to organize), but even with that, I don’t see how it would be possible to destroy life in the oceans, at this point.