Heat and Humidity Are Already Reaching the Limits of Human Tolerance (2020)

It's also a way to make meteorology seem more engaging. The weather forecaster gets to tell you that yes, the hot feels hotter (the same way the wind chill lets them tell you that the cold feels colder). It's not as scientifically useful, but the actual data is available to scientists who care about it.

Ordinary people prefer to know how to dress, and the heat index/wind chill are actually OK at that.

Can you elaborate on what you mean here?

If you learned such a thing you learned incorrectly. Mojave is dry. The article mentions this, but the relevant measure is the "wet-bulb temperature", which combines heat and humidity. The name comes from the technique of wrapping a thermometer in a water soaked cloth and passing air over it, so that it takes into account evaporation. Thus the wet-bulb temperature is the lowest temperature that can be reached through evaporative cooling alone.

No matter how much adaption you have to the heat, nobody can exercise and do normal (let alone strenuous) continuous outdoor activity with a wet-bulb of 90°F or so, and ~95°F wet-bulb is about the absolute limit of how much a human can survive longterm (ie., someone could still last an hour or two), even just lying in the shade. No amount of water you drink can help you if the air is at saturation already.

So there is genuine concern that parts of the world will literally become uninhabitable without universal mechanized cooling or other extreme adaptive measures (going underground say). And while the general focus is humans, of course every other animal is the same plus or minus some number of degrees.

It's 3000 feet above sea level. It took me at least six weeks to stop waking up short of breath. My bra size permanently changed due to my rib cage enlarging due to my lungs enlarging.

Drinking caffeine by day and alcohol by night can land you in the ER with heat stroke. No, drinking enough water is not sufficient. At altitude and in high heat, you also need electrolytes (think gatorade).

I grew up in Georgia. That thing they say about "It's not the heat. It's the humidity." is spot on.

The Mojave gets six whole inches of rain per year. It's just south of Death Valley which is below sea level precisely because it's so extremely dry that what would normally be a deep lake full of water is bone dry.

Cool factoid: If you get crazy levels of rain in short order, like an inch or two in a day, all the dry lakes flood for some weeks and shrimp hatch out.