Global civilisation collapse is unlikely to be a one-day event. It will be a gradual process over several years, for instance there would be a financial market

Global civilisation collapse is unlikely to be a one-day event. It will be a gradual process over several years, for instance there would be a financial market crash, than an obligation market crash and a global debt crisis, then several of the G20 countries would fall into deep crisis like civil war or dictatorship, global trade will come to a halt, wars on resources would erupt at many points on the globe, then for instance the EU would cease to exist in fact but not in law (governments would pay lip service to it for years without actually complying to its policies) etc. We wouldn't be able to say for sure "this is it, today the civilisation is collapsing". However, at the end of a several years period, billions of people would have been killed by famine, epidemics, wars, etc. Just like the fall of the Roman Empire has been dated to some more or less arbitrary date, but actually was a many years process, actually beginning a century or more before the point we date the "event"; and for people of the time, the Empire wasn't actually dead before several decades at least (and Justinian failure to capture back Rome). So we date the "fall of Roman Empire" to september the 4th, 476; but it was in the making for a century, and wasn't a done deal for another century. Similarly, the "fall of the thermo-industrial civilisation" or "American Empire" or whatever else we'll call it will be set up to some day at some later date in the future.