Interesting you should post a link to World Turned Upside Down. I've just finished reading Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century by Geoffrey Parker.

The C17th experienced the Little Ice Age when average global temperatures were on average colder than they are now due to a combination of lower sunspot activity, more volcanic eruptions and changes in El Nino activity and so on.

This led to more extreme weather events deleteriously affecting harvests leading to famines and disease and so on. These effects were exacerbated by rulers continuing wars over territory and thus adding burdens of taxation and conscription on their populations. Populations declined markedly and took some time to recover.

Of course, there were differential effects globally, with Germany (30 Yrs War) particularly badly affected but Tokugawa Japan less affected due to its isolation.

The coming 'collapse' is likewise also going to affect countries and regions differentially, partly dependent on the resilience and cohesiveness of their societies.

According to Jem Bendell in Breaking Together collapse has already started across several sectors (eg, climate change, global food security, energy security etc). It's just that many of those in the privileged world are not aware of it yet.

Migration could be one symptom.

Bendell doesn't mention wars. Unlike the dynastic and territorial wars of C17th, present wars (Gaza, Ukraine) are about unipolarity vs multipolarity (and, of course, competition for diminishing resources).

As I said, the key to survival depends on the cohesiveness and resilience of societies, as well as individual resilience.

Many societies today seem divided amongst themselves. As collapse accentuates, these societies will find it hard to survive, let alone thrive, as humanity moves into a radically different world.