Ah, back I see. Well, lets imagine for a moment that the world is heading for a catastrophe of some kind. (What's that? You don't say...) So let's use Global Warming as the scenario then.
- What is causing GW? Too many people using up resources, leading to changes in the ecosystem and the weather system.
- What is the timescale for GW? We don't know. Every year we are revising our estimates to nearer and nearer in time, and estimating worse and worse effects over that shortening timespan.
- Can we just stop using those resources and let the systems stabilise? No, because we are dependent on them, and if we stop using them, another population will begin using the resources, and we'll be evolutionary statistics.
- Can't we impose a global moratorium on using resources? Try telling that to China and India, who are pulling up populations from the depths of abject poverty to some semblance of a living standard, that they're no longer allowed to use resources. Go on, I dare ya!
- How about if we all become tree huggers and hippies and scatter throughout the bush, and suppose that we found a completely zero impact way to sustain everyone, what about that? Nope, because even if we all stopped everything that causes pollution or environmental impact right this instant, the effect would roll along for decades and the world itself will become less and less hospitable and habitable in that time.
If I were a superpower, my plans right now would already be laid out in detail and stored in a filing cabinet against the day that I might need to use them... Cold countries? Nuclear winter will bury them under a block of ice for at least a few centuries. Don't waste nukes there. If you are a cold country, your plans should include mass evacs to the tropics. Temperate European countries? Take out as many large population centres as you can, reduce their capacity to resist. Africa/Middle East/China/India/USA? (Depending on whose plan you're reading...) Carpet those suckers in whatever you have, send in as many troops as you can before the big chill sets in. Indonesia/Australia? Send in troops and then immigrants, don't waste nukes, you need somewhere that isn't glowing...
Not the best scenario, but it is time to make plans of your own, just in case. It probably won't happen, but if you've thought about it then you're that much better prepared than someone that hasn't spared it a thought. Also, I hope and feel that commonsense will prevail in most cases, but there are some nuclear powers out there now that are under barely rational leadership, and under the right circumstances that could trigger a brief outburst and as you saw in my other article, a really bad climate change would follow that pretty quickly.