I think there will be a few levels of displacement and migration waves from climate change. Things like sea level rise, rising temperatures, and more frequent

I think there will be a few levels of displacement and migration waves from climate change. Things like sea level rise, rising temperatures, and more frequent blizzards or cold snaps act over decades. That'll be a gradual shift in migration patterns, not a crisis. But a lot of the second-order effects operate on much smaller timescales. Hurricanes can cause large dislocation on the timescale of a week: look at Rita & Katrina in 2005, which cut the population of New Orleans in half and gridlocked all the freeways out of Houston for days. Wildfires also can trigger large migrations within a matter of weeks. We've been lucky that most of the West Coast wildfires have been in relatively unpopulated areas, but if one were ever to jump highway 280 in the Bay Area or get into the Pasadena/Glendale/Burbank area by LA, we could have a mass evacuation crisis. Crop failures too: that's what's driving a lot of the Middle East migration. If it happened in the U.S. or China millions of people would starve. There's also violence caused by resource constraints. We see that in Central America now, in the Middle East, and increasingly in the middle of U.S. cities.