Such zones won't necessarily be very stable. Current climate trends point towards an increase in hot humid conditions in some areas, increased aridity and droug

Such zones won't necessarily be very stable. Current climate trends point towards an increase in hot humid conditions in some areas, increased aridity and drought in others, and associated extreme weather conditions. If there's any one culprit to point to, it's the water vapor increase (forced in turn by the increase in atmospheric fossil CO2 and CH4). This also affects wet-bulb temperature (which sets an upper limit on outdoor activity): https://climate.nasa.gov/ask-nasa-climate/3151/too-hot-to-handle-how-climate-change-may-make-some-places-too-hot-to-live/ https://climate.nasa.gov/ask-nasa-climate/3151/too-hot-to-ha... Climate-resistant design and construction is going to be a booming field in years to come. Termite-type underground construction, fire-resistant bunkers in dry zones, maybe flood-resistant floatable housing in flood zones, solar-powered AC units, etc. A lot of climates are more tolerable if you have a refuge to escape to.