Someone could make a “Einstein dehumidifier” using 19th century technology and roll it out across the world. If embedded in buildings it could cool them constantly with no electricity required.
Most modern ACs in fact dehumidify and cool in one step with a compressor and then use the collected water to help carry heat away from the compressor by letting the water evaporate into the exhaust to save power (it's why you rarely have to empty water from modern dehumidifying ACs).
Anyway, the best way to learn more about this is to search for resources describing the "psychrometrics of evaporative cooling". Psychrometrics is the study of the thermodynamics of air and water vapor mixtures. Learning about the psychrometric chart, in particular, is helpful since it is a very clear, expressive tool that will illustrates how adiabitic (no change in thermal energy transfer) cooling can occur by adding humidity to dry air.
I think this entry from engineering toolbox provides a good start: https://www.engineeringtoolbox.com/evaporative-cooling-d_698...
Ultimately all that really works in our modern world at scale in such a heat wave is powered air conditioning, so ensuring that electrical power is not interrupted during such an event is of paramount importance if we are to avoid this new sort of natural disaster.
Human societies have been historically very bad at handling large scale migrations, but it's about to become necessary.
https://www.theguardian.com/us-news/2021/jul/08/pacific-nort...
https://www.theguardian.com/environment/2021/jul/08/heat-dom...
Migration is not going to cut it. Climate change is making weather more chaotic and unpredictable. Escape is impossible. The only place you can go where the planetary weather system’s disintegration does not pose a danger is space, where the absence of that same disintegrating weather system makes survival even harder.
Reversal is the only option.
Reversal is not really an option either; the best scientific evidence I've seen is that we've already past several tipping points that will accelerate warming regardless of what we do, and even if we haven't, we've had about zero decrease in worldwide CO2 emissions and a terrible track record in getting humanity to work together for common good.
Not saying you’re wrong, though..
Instead you build and live in highrise/towers - that gives cheap ventilation which is a half the solution.
And I liked the siesta and the following it very active life till deep night in Spain - another natural adaptation to hot climate. It makes for much calmer and steady life rhythm and feeling.
I mean, I'm sure this is valid in some places but having lived in high rises relatively far north in Canada let me tell you it is very possible (and in my experience very common) to build high rises that retain heat so well they basically bake the occupants in high heat/humidity.
I doubt most of North America's high rise apartment buildings above some latitude are particularly well equipped for this, so there's almost certainly a shift required in how you build them.