[falcolas]

> It’s not THAT hard to cool down even if you’re incapable of sweating to do so.

How would you recommend cooling down for hundreds of thousands of people at a time? I have to assume that those affected wouldn't have easy access to AC.

[sjducb]

Fill a bath and get in it. The groundwater is usually much colder than the air.

However there is a limit to how long you can live in the bath.

[falcolas]

And how many bath tubs there are per-capita. Many newer homes are built with only showers.

You also have to worry about power when it comes to having access to sufficient water to cool a person in the first place.

[pengaru]

Parking yourself nude under a cold shower will keep you alive, assuming you don't run out of water.

There's no need for the bath. The shower will probably work better actually since it's constantly disposed down the drain after picking up some heat, and replenished with subterranean-temp fresh water running across your person.

[jncfhnb]

You do not need to submerge yourself underwater if that’s what you are suggesting. A bucket of water for your feet will do lots. A shower is good too.

[falcolas]

I'm not sure a bucket would be enough to cool a person down if they have no other form of heat dissipation available to them - specifically I'm not sure feet alone could dissipate heat fast enough. If the water is too cold (around 70°F IIRC), your body would constrict the blood vessels to your hands and feet, limiting how much heat could be moved to those extremities from your core.

Hence mentioning a bath tub.

Some interesting reading to go along with this topic:

https://ntrs.nasa.gov/api/citations/19750007244/downloads/19...

Of particular note is the need to remove about 1k BTU/hour when walking/doing light work, and that's only from metabolic heat generation.

And 1 BTU raises 1 pint of water 1 degree, so 1k BTU/hour would raise 5 gallons of water by an unrealistic 25° every hour.

[jncfhnb]

You’re going to need to set some practical constraints here.

Can you survive wet bulb temperatures given a bucket of water indefinitely? No. Can you survive working hard labor with the water bucket? No. Can you survive wet bulb events significantly higher than the threshold? No.

Can you survive several hours in a typical (current typical) wet bulb event? Yes, definitely. Bucket of water is fine.

[falcolas]

> Can you survive several hours in a typical wet bulb event?

I'm going to vote maybe. At best, it'll be close.

Resting metabolic output is about half the active value I provided (per NASA's PDF). That means for a bucket of water that starts at 32°, you have 5 hours before the bucket is also 95° if you discount ambient heating from the air, circulatory constriction, and assuming no prior conditions.

Since you can't discount those (and are unlikely to find barely-not-frozen water for an entire city's population), survival for more than an hour or two is nowhere near guaranteed.

[carapace]

Many of the places at the forefront of this threat also have water scarcity issues. There's also the problem of what to do with the water once it's heated up. You could pump it back into the ground to cool off, but eventually you're going to heat the ground itself and have an even worse problem.

[generic92034]

Also, can we all be sure that electricity will be available during such an event?

[jncfhnb]

Heat waves are dangerous. My point is that wet bulb events are not a magical inflection point.

The point to take away is that humidity matters in addition to raw temperatures. Not that there is a specific threshold at which things matter or didn’t matter.

[generic92034]

I think that point was well understood, by falcolas, to whom I was replying. But your assumption that it is not that hard to cool down seems a bit strong to me.

In some countries electricity becomes unavailable quite regularly, so relying on A/C during a crisis like that might fail. And that is assuming that A/Cs are common (they are not, in large parts of the world).

Cooling yourself down by using water from a tap may also fail, if, in such a situation, everyone in a city tries to do that. You are assuming a very high level of infrastructure and no critical failures.

[jncfhnb]

You don’t need much water. It doesn’t need to be that cool either. If you lack access to the water required to do this, which does not even need to be clean, then the lack of water is probably the bigger crisis.

Heatwaves and infrastructure failures can undoubtedly be serious threats. But the vast, vast majority of people survive wet bulb events when they encounter them.

[generic92034]

So you are saying a small amount of water would be enough to cool you down when it is (for example) 35° C at 90% humidity? How would that work? Evaporative cooling is out, for the most part and a small amount of water would be heated up to 35° C in no time.

[jncfhnb]

You just put your feet in the water and transfer heat to the water. It would not heat up to 35 in no time.

[pengaru]

> Heat waves are dangerous. My point is that wet bulb events are not a magical inflection point.

If this imaginary graph has an inflection point, I can't think of a better one.