Between the options of devastating natural disasters and
nuclear warfare, which are choices that would actually destroy the world, nuclear war is my top pick to do the job. Now this event would generally destroy all plant life because of the effects it has on the sun, which is called nuclear winter. It's a good thing the government of Norway is among the most prepared countries just in case we end up destroying the planet we live in. In this regard, I'd be preparing for a retirement plan in this country!
