"Wet bulb" temperature is the temperature + relative humidity at which water stops evaporating off a "wet" thermometer bulb. If air is sufficiently humid (saturated w/ water vapor), evaporation will no longer cool the bulb, and it gets continuously hotter. [...]
Dry air has essentially infinite capacity to absorb moisture, so, humans can survive in very high temps if the air is dry [...] But, the wet bulb is not about heat, per se. It's about the absorptive capacity of air. A wet bulb temperature in the mid-80s F can, and does, kill humans. Heat waves in the EU & Russia in 2003 and 2010 killed over a hundred thousand people at ~ 82 F. [...]
If sweat won't evaporate, our body temp rises, continuously. And when body temp hits ~108, we're dead. For a vulnerable person in wet bulb temp, this takes much less than an hour. Naked. In the shade. [...]
So, what does this have to do with you? Well, up until last ~ 40 years, wet bulb temperatures were extremely rare on this planet. But that's over, now. We're already seeing multiple wet bulb temperatures per year in multiple locations. By mid-century, parts of the Southeastern U.S will see weeks of wet bulbs every year.
This is quite bad. Thousands of people will die on each of those days.
This has ... implications. Human habitations get very difficult to manage when thousands and thousands of people are dying every day, for weeks, every year.
This is actually an active area of climate science and resilience study.
So, the moral of the story: Many of the places humans currently live on the planet are on their way to being functionally uninhabitable by humans. They will have to move. Some may try to "adapt," and some may pull it off. But this will be exceptionally difficult.
If we do everything right, starting now, there's a chance we could return some of those places to habitability for future generations, in the 3rd millenium or so. But as of today, we've already roasted most of them. Carbon emissions have a very long life in the atmosphere.
So please, help your city prepare for the refugees. Depose the NIMBYs in your city government. Defeat the car-stans who deny that all of this is happening.