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Comment by boplicity | Hacker News Reader

Kim Stanley Robinson's recent book The Ministry For the Future starts with a very disturbing scenario: A heatwave with a "web bulb" temperature of 35 Celsius.

It turns out, in those temperatures, even young and healthy people can't survive. Combined with power outages, as happens in the book, everyone living under such a heat wave will likely die.

It's looking increasingly likely that such heatwaves are possible in the future, and possibly quite deadly. This could result in the mass deaths of many people, especially in poor tropical countries that don't have a stable infrastructure to cool most people during such a heatwave. I hope a mass death event from a "web bulb" 35C heatwave never happens, but I'm losing hope, especially with the increasing global temperatures, and the very lackluster progress being made on carbon output.

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> Combined with power outages, as happens in the book, everyone living under such a heat wave will likely die.

That's an exaggeration. Extreme heat (including heat waves that exceed this threshold) happen semi-regularly, and the death rate when they occur is nowhere near 100%. More like 0.1% or less.

Electrically-powered air conditioning is not the only way to cool a human body.

Simply escaping to an underground or substantially enclosed area is sufficient for periods of up to a few days, or even weeks depending on the thickness of the walls. Car parks, cellars, caves, etc... all retain a relatively constant temperature irrespective of temporary swings of the air temperature outside.

Similarly, immersing oneself in a body of water below about 36 C is also sufficient, and that's typically available even if the local air temperature and humidity exceeds safe levels. E.g.: Rivers "carry" the cold down from mountains, and are safe havens during temperature extremes. Even the local pool is sufficient, because water has such a massive thermal capacity that it won't heat up anywhere near as fast as the air around it.

At times like this you see people filling up their bathtubs and just hanging out in there until things blow over.

More worrying is what happens to wildlife. Some animals simply can't escape like humans and most animals can. For example in Australia a recent heatwave killed something like half of all flying foxes!

Many apartments don't have a bathtub, only a shower. And if everyone keeps tap water running, the pressure will drop down to trickle. Cold cellars can be in short supply, underground car parks tend to get hot too. And seems you probably never bathed in 35°C water, it's definitely not refreshing.

And there are psychological issues that people just don't know what to do till it's too late. I was living an apartment with only 1 southern window, the heat was hard to vent. Once during a heatwave I found myself in a weird lethargy then I started going sick and then I found out the thermometer shows 40°C inside. I went outside immediately. Were not a healthy young man, that could have ended up badly. Since that I never underestimate the heat.

That does not mean 100% fatality rate is possible but it definitely might be more than 0.1%.

"Many apartments don't have a bathtub, only a shower. And if everyone keeps tap water running, the pressure will drop down to trickle."

People don't have trashcans, storage bins, etc?

"And seems you probably never bathed in 35°C water, it's definitely not refreshing."

Where is this 35C water coming from?

Also, if it's a humid heat, there are likely to be natural or artificial bodies of water around. Hopefully the people have been taking care of them and they aren't a cesspool.

Sure, some people may die, but it should be very low.

Edit: why downvote? All the excuses the previous person gave seem petty to me, so I'm wondering how that person came to their conclusion. Especially for where that hot water is coming from.

> WB 35 °C (95 °F) – theoretically equivalent to a heat index of 70 °C (160 °F), though the heat index does not go that high

I’m inclined to say that this is not very survivable, regardless of your precautions, if your air conditioning has died.

I'm not sure you understand wet bulb and heat index. Heat index is largely irrelevant when talking about the precautions mentioned. The actual temperature is no where near 70C, and actual temperatures matter when talking about cooling that does not use ambient air (and evaporative cooling assuming 100% humidity in this case).

A wet bulb of 35C means that there is a thermometer covered with a wet cloth reading that temperature. That could be 35C with 100% humidity, or it could be a higher temperature with a lower humidity.

Can you explain how your air conditioner keeps you cool? Do you think this machine is the only thing that can perform a similar function? It's all about removing excess heat from your body. An air conditioner does this by cooling air and removing humidity. This can be from the cool air on your skin and the ability for your sweat to evaporate. When your sweat can't evaporate you need another way to transfer heat. Water is very efficient for this due to its specific heat (anything at a cooler temperature with sufficient thermal mass can work). Some people can even become hypothermic in 27C water if left in it long enough.

Edit: I guess people just downvote things they don't like or find to be inconvenient.

Re-read the comment you're responding to.

I did... and?

You come off as browbeating him, accusing him of not knowing things, when he said a small thing that was fully accurate if not precise. That's why you're being downvoted.

"I’m inclined to say that this is not very survivable, regardless of your precautions, if your air conditioning has died."

How is that fully accurate? It seems to me that "not very survivable" is not accurate and is an over exaggeration. I don't expect a 50% death rate, even 10% would be extremely generous. It would be like me saying linux desktops are very common.

This is silly/pedantic. He's talking about being in a typical house with a dead A/C, experiencing the equivalent of 70C. Please tell us how you're going to survive that circumstance. Answer: you're not. You're going to change your circumstance, since it's not very survivable. You're going to leave your house and try to find somewhere cooler. His statement is accurate if not precise.

Lol it is not the equivalent of 70C. Please see the other resources people have posted here about understanding wet bulb temperatures. Even a wet bulb of 35C can be tolerated by most for hours - 70C could not.

I would not leave my house. My house has insulation and thermal mass, which would delay the tempature from reaching that level until later. I could use water to cool myself, whether in the bath tub or a trashcan. I could use a fan if there's power (depends on the temperature and humidity to reach that wet bulb). I could use frozen objects (even without power, the freezer will stay cold for at least a day). I also have a generator to power these things if there's a short to medium term outage.

Their statement was not about changing one's circumstance. It was that even with precautions, it's not very survivable. This is neither accurate nor precise. It is very survivable with precautions.

You're describing tactics that will lead to your tenuous survival. If the heat doesn't last too long. And if you don't have anyone else is your house, not a likely circumstance globally considered. Almost like 35C wet is not very survivable. Your claim that 35C wet can be tolerated by most for hours contradicts the article, and your claim that it's more tolerable than 70C dry contradicts the concept of heat index. Anyhow, you're welcome for my charitably stepping in to let you know why you're being downvoted. You're stuck on pedantry and straw manning and pointless unproductive argument. The Hacker News collective had you pegged, and I'll just join the downvote parade and ignore your type in the future. I'm out.

I feel sorry for you.

Thanks for making my argument for me anyway ;) you said it better than I probably could.

Even if my air conditioner was still functional, its output, the attic-based tubing used to push the air around, and the cheaply-built and leaky house to which it all attaches would never be able to keep out the heat.

Also the outside end of the heat pump wouldn't be able to cool off, so it wouldn't be making any cool air inside anyway. The tipping point there seems to be way lower than the numbers above, around 50 C / 120 F.

Huh, that’s a good point. Never considered that.

You’re being unreasonably optimistic. It’s wishful thinking.

How so? What part is unreasonable?

I was specifically questioning things like where is the hot water coming from, people without tubs can't figure out how to save water, etc. Those claims sound overly pessimistic and simplistic to me.

It's not about saving water, it's about immersing yourself in water. You seem to have a different natural disaster in mind.

It is about conservation of water because as the person pointed out, you can't have a bunch of people running water continuously. You can store the water in a trash can or other large container. You can immerse yourself, or parts of yourself, in this water. You can even make a gravity shower to reuse the water since it's used for cooling and not cleaning. Replace the water when it gets too warm. This would greatly reduce the water usage compares to continual showers and provides a suitable substitute the previously mentioned bath tub when one is not available.

In some places people used to pump groundwater out of the ground to use. That water should be at a temperature of around 10-20C. So you could soak your feet in that to cool off.

> Cold cellars can be in short supply

If this starts to happen semi-regularly, you can bet my garden will turn into a little hobbit hill/cellar.

That said, I agree that if it happens suddenly to that extend, we would likely be looking at more than 0.1%.

> underground car parks tend to get hot too

This is something that has puzzled me every time I park in the underground garage under City Hall in Palo Alto. It is always so hot down there compared to the outside air.

I was about to ask if anyone knows why that is, and then realized I could search for the answer:

https://www.google.com/search?q=why+do+underground+garages+g...

Lots of interesting opinions there, including a previous HN thread.

One discussion I liked showed up when I'm signed into Google but was missing from an incognito search:

https://philip.greenspun.com/blog/2013/07/05/stupid-geophysi...

This reminds me of how the London Underground used to be much cooler, but the trains have raised the temperature of the clay surrounding the tunnels sufficiently that it never cools off:

https://en.wikipedia.org/wiki/London_Underground_cooling

Relevant: https://youtu.be/Y8RfeAmLfn8

There's also all the body heat, and the resistive braking of the trains which is being phased out.

Hello 2013: https://news.ycombinator.com/item?id=5997368

True. Which is why what always puzzles me is that cities like Austin or Phoenix are gaining population. It's so hot there!

Karachi, and Sindh at large often goes through periods of +35 wet bulb.

People can jump into fountains, or other bodies of water, hide at home, airconned buildings.

In the end, people can try to brave it, and wait for the relatively cool evening.

Wet bulb thermometer is the kind that a pair of thermometers are mounted together with one wrapped in wet cotton and the other dry. Typically between the two glass tubes is a little look up table that gives humidity from current dry bulb temperature and delta between the two.

I don't know what exactly environment reaching 35C/95F web bulb means, but considering 1) it indicates temperature of a thermometer cooled by evaporation, and 2) body temperature of a human is ~40C/100F, I think it means evaporative cooling aka sweating is becoming useless. It won't be a huge stretch to consider that unsurvivable.

Yet people did. The heat stroke at 35C° wet bulb if far from instantaneous.

"I think it means evaporative cooling aka sweating is becoming useless. It won't be a huge stretch to consider that unsurvivable."

This assumes there are no alternatives to evaporative cooling via sweat.

Indeed. Strapping on a pair of active CPU heatsink through a B6 sized aluminum cold plate to the back of waist helps immensely in that kind of climate. But it needs constant 12V/0.5-1A DC supply.

What are you even talking about?

My legitimate comments get downvoted and crap like this does not...

That’s what I do when humidity is unbearable but air temperature is below body surface. Works ok.

Wet bulb 35C is equivalent to a heat index of 160F.

One issue that people who haven't experienced extreme heat might not realize is a lot of people just pass out really quickly. While it takes a while to go past the point of no return and they theoretically could be egressed to somewhere they can cool off and recover, if they're alone, they're not going to.

I understand you are probably American and therefore not used to Celsius but just so you know the body of a human is around 37.7 °C. 40 °C is already life-threatening.

Wet bulb of 37C does not happen semi-regularly. Table S2 of the article shows a TW of 35+ has only happened 14 times in their ~30 year dataset so I would even hazard a guess that TW of 37 has not yet happened.

These events are usually short (for TW >35, majority only last an hour, see Sup fig 2), which is perhaps why we are not seeing many deaths associated with them.

With regards to immersing oneself in water, a bathtub is good so long as groundwater is available; if everyone starts filling their tubs for every heat wave it might start becoming more scarce. I would have thought natural bodies of water like the sea would have been a good choice, but the authors point out that in one region where wet bulb temps >35 were happening they also observed frequent sea surface temps >35 too (sup fig 16).

There are ways to survive and you have provided good ones, but they won’t be available to all who experience these events if they continue to increase in number. And excellent point about wildlife! That’s a whole additional side of it that will probably get lost in the mitigation effort…

Air is an insulator, 35 degree weather will cause extreme internal temparatures but 35 degree water allows you to transport all your excess energy to the water. 38 or 40 degree water would be deadly, but I wonder what the air temparature is when it gets that far.

The problem with lots of people in water is that leads to drownings.

"There is a clear connection between heat and drowning. That's when people want to go in or near the water, and the risks of drowning increase," FSL's Executive Director Kristiina Heinonen told Yle in July:

https://yle.fi/uutiset/osasto/news/drowning_deaths_reach_10-...

Well yes, and the problem with lots of people out of the water is that it leads to traffic accidents. Is there a name for this fallacy that proclaims things risky by comparing them to a theoretical situation where everyone is immortal?

There's a difference in that deadly heat can make people who cannot swim, start panic crowding in the water in tens of thousands of people large groups?

Sounds to me like a mostly not seen before thing

> Is there a name

"False analogy" is what comes to my mind, maybe there's something better

> start panic crowding in the water in tens of thousands of people large groups?

I guess it depends on where you are, I live on the Mediterranean, where, if you panic in the water, you're just standing in calm water. I imagine the ocean is much scarier.

> maybe there's something better

I think we do need something better, I see it too often for it to not have an exact name.

> I guess it depends on where you are

Yes, in my case I was imagining a wide river close to a many millions people city, and people from the slums (no AC) go there to cool down, and more and more people arrive all the time to the river, pushing those already there outwards, deeper water, people cannot swim

At rock concerts 10 000 people can create dangerous pressure, I wonder if a deadly heat wave and the chance to cool down at a specific place can do that too

Or maybe people would spread out along the water, but at the same time, it might be hard for an individual person with occluded vision to know what makes sense to do

Sometimes people rush out from a building in panic, everyone gets stuck in the door opening

Well... people are resourceful. I mean, we may have gotten soft living in civilisation... but we still have some survival instinct. Shade, bathing, burrowing etc.

Still, that factoid is troubling. These are conditions that exceed humans' operating conditions. We're used to that on the cold side. Plenty of people thrive (miserably) in places that get cold.

But, there are actually far fewer good cooling options. Air conditioning is more complicated than heating. You can heat with fire, warm clothes. Even exercise, though this is not sustainable. A sauna is nice, but people don't live in their saunas until temperatures get tolerable.

Also, the heat cutoff is more of a universal. A lot of organisms seem to start failing at temperatures like this.

The human body can generate heat by eating food, it's just a matter of insulation to stay warm. Our bodies can't generate cool at a wet bulb of 35C. That's a huge difference.

How tens of millions people can escape underground or rivers? I think that there will not be space available for most of them.

I don't think space is the issue. Most people live 200 miles from the coast. If that gets as hot as the inland, people will fan out to find whatever shelter they can. While I hope there are cool materials science breakthroughs that can withstand high temperatures, I imagine a lot of people will make homes in caves and underground, like a nuclear bunker.

That would definitely change cultures and economies, but if you can't get out of those places, it might be your only option.

> Extreme heat (including heat waves that exceed this threshold) happen semi-regularly

The threshold is wet bulb 35 for 7 hours. That is when fit young humans can't survive. Older people die well before that of course.

And no, it doesn't happen regularly. I wasn't aware it had happened at all, although others here say it has. But it has come close. From https://www.telegraph.co.uk/global-health/climate-and-people... :

> Jacobabad crossed the 35C wet bulb threshold in July 1987, then again in June 2005, June 2010 and July 2012. Each time the boundary may have been breached for only a few hours, but a three-day average maximum temperature has been recorded hovering around 34C in June 2010, June 2001 and July 2012.

These people don't have the escapes you mentioned. They are in a city with no running water and no cars, let alone car parks. There is no river, but there are a couple of small lakes.

I’m pretty sure Jacobabad has cars.

Some people having cars != everyone having cars.

But the claim wasn't everyone having cars, it was "They are in a city with ... no cars."

If 1% of people have access to cars it’s pretty close to “no cars”.

Jeez what a hot place... Any idea what geographic features make it so dang hot? It's not too far from water (just looking at a map).

I lived about a hundred miles from Jacobabad in 1987. It was known as the hottest place in the world then along with Sibi to the north. I remember 50C temperatures but it was dry and I used to walk outside to the market around noon. Once my school principal saw me walking without a hat that summer and lectured me about safety but I didn’t feel anything bad. It helped that I was thin and had a high surface are to volume ratio so heat never bothered me. My father worked for Exxon and we had free electricity and every house had massive 8-ton air conditioners, so the heat was never a problem for us.

Sibi is in a hollow formed by some mountain ranges to the north. Perhaps hot winds from the south get trapped there. Not sure about Jacobabad though…could never find any reason why it was so hot.

Another time I was in a car with no AC right after a rainstorm, and it was so hot in the backseat that every time the car stopped the heat became unbearable. When the car was moving we had some wind and it helped.

In Canada I’ve always noticed the temperature can be 5-10 degrees cooler under trees in a forest. Not sure if it’ll be so cool with high humidity but certainly trees will block the sun and trap air cooled by the ground, so they are the best defence against global warming.

Thanks for sharing!

What city doesn't have running water?

The city can have running water while some people living there don't. Slums or homeless encampments are common the world over in large cities.

It means some people simply have no means to escape such heat and will likely die.

In the US, they sometimes open cooling centers during heat waves so homeless people and poor people have a place to go. I never went to such but they did that in Fresno and bus rides were free if you said you were going to a cooling center.

Lots. Many cities have running water for only a few hours a day.

And there may often be only one tap per 100 people in densely populated slums.

Many cities I would think. My spanish teacher lives in a big city in Venezuela and they use water tanks and electricity is rationed.

Here's a discussion of heat index and wet-bulb temps, with records from around the world.

https://www.wunderground.com/blog/weatherhistorian/record-de...

The most dangerous / frequent occurrences seem to be measured in the middle east near shallow gulf coasts. Appleton Wisconsin holds the continental US record, apparently?

This is from 2011.

This looks more updated: https://www.weather.gov/jetstream/hi

and says:

> The highest dew points, and therefore the highest heat indices are usually found near warm bodies of water.

> In the world, the warmest water is found in the Persian Gulf where the water temperature typically reaches up to 90°F (32°C) in summer. Therefore dew points will be that high as well.

> The highest dew point ever recorded, 95°F (35°C), was recorded at Dhahran, Saudi Arabia, on July 8, 2003. With an air temperature of 108°F (42°C) the heat index was 178°F (81°C).

> In the United States, the highest dew point ever recorded, 90°F (32°C), was recorded at the New Orleans Naval Air Station, on July 30, 1987, Melbourne, Florida on July 12, 1987. Heat indices were in the 130's°F (50's°C).

> Appleton, Wisconsin also had a 90°F (32°C) dew point on July 13, 1995 with a heat index of 149°F (65°C)."

So, it happened once, in Saudi Arabia?

Even if they are not that deadly extreme heat waves could crash power grids (which is very costly due to lost productivity), kill crops and livestock, damage infrastructure, cause extreme increases in energy demand, and generally cost a shitload of money.

A higher frequency of extreme cold in winter in areas that are not accustomed to it, like what recently happened in Texas, may also occur with similar consequences.

I don't think climate change will be a catastrophe movie directed by JJ Abrams. I think it will be a gradual process in which we pay back the "loan" of fossil fuel use with interest.

We put our civilization on a credit card without knowing the interest rate.

We could have really slowed down our running up the balance in the 1970s and 1980s with nuclear power, but we didn't. We could still be doing that plus deploying a lot of renewable and storage tech that was not mature back then, but we're doing far too little of that. We are still adding to the card balance and we still don't know the interest or the repayment terms.

If there are feedback loops in the climate system that we trigger, the loan could be an ARM with unscheduled interest rate increases and balloon payments.

Our children get to inherit most of this bill.

The smart thing to do now would be for everyone around to world to start digging underground relief shelters.

Probably everyone painting their roofs white would help too.

And starting with this, (digging, climbing the roof) when it's warm already isn't going to end well

The municipalities in the relevant places ought to advice people to prepare well in advance (and how)

Huh. Glad to read what you wrote. I trust you over actual scientists, because you wrote it so well in a short few sentences. Thanks for the info!

> It turns out, in those temperatures, even young and healthy people can't survive.

Of note: that’s literal, even doing nothing and sitting in front of a fan you can’t cool down.

And do one of the issues 35 WBT “hides” is that any activity lowers the heat stress threshold. Sugarcane workers are already dying due to heat stress today, and have been for a while. There’s been an “epidemic” of “kidney disease” in central american sugarcane fields for a decade now, with young men showing rates of kidney diseases 15x the norm.

According to Wikipedia[1]:

"Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of 32°C (90°F), equivalent to a heat index of 55°C (130°F). The theoretical limit to human survival for more than a few hours in the shade, even with unlimited water, is 35°C (95°F) – theoretically equivalent to a heat index of 70°C (160°F), though the heat index does not go that high."

So the practical limit is indeed much lower than 35°C; that's the limit at which you're basically going to fall over and die.

[1]: https://en.wikipedia.org/wiki/Wet-bulb_temperature

And people START dying, en masse, at 28C wet bulb (see chicago and vancouver heat waves)

> en masse

I'm not sure that phrase means what you think it means... Yes, there were ~600 tragic deaths in BC from the heat dome, but en masse means 'as a whole' or 'as a group', and a .012% death rate does not really qualify there.

If you understand French you'd know it just means in large quantities.

But we aren't speaking french. We are speaking english and in english en masse doesn't mean a tiny fraction of people/group.

At that heat, counterintuitively, sitting in front of a fan will only heat you up faster.

i probably have a comment somewhere recently, but singapore is already in WBT >35 conditions in the day. it eases to around 30 at night or when rain falls.

as long as power is running, it's actually fine in this country, but that's because we've designed our living space around the heat. it is entirely possible to never be exposed to the sun in a normal day in the life of a working resident here if you stay in the right neighbourhood, and this includes the daily commute, hobbies, physical activity, going out for drinks etc.

more and more of the country is being built underground and more and more of our air is becoming conditioned. this is the arcology of the future and it is somewhat pleasant.

edit: actually i think our infrastructure was built around protecting us from the harsh and unpredictable tropical thunderstorms and the protection from heat turned out to be a nice bonus.

Lack of sun exposure can cause hypovitaminosis D, which is a known risk factor for COVID-19 and other infectious diseases. It also impacts nitric oxide production which is a factor in cardiovascular system health. Supplements can mitigate the problems to an extent but are inferior to natural sun exposure.

And before anyone brings up skin cancer, there is no reliable evidence that brief daily sun exposure increases all cause mortality.

> Supplements can mitigate the problems to an extent but are inferior to natural sun exposure.

Inferior how?

Supplements for fat soluble nutrients like vitamin D generally have poor bioavailability unless used with specialized emulsifiers for insoluble compounds that aren't widely used [1]. The body has a hard time buffering and storing the excess, which it can't filter out through the kidneys.

It's like fast acting insulin versus insulin produced by a functioning pancreas - it's going to keep someone alive but it's not ideal for the body long term.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6631968/

> Supplements can mitigate the problems to an extent but are inferior to natural sun exposure.

I've never heard of such a claim, and that seems unintuitive. Why would that be? Do you have a source you could direct me to to learn more about this?

I have heard that sunlight also causes the skin to produce nitric oxide, which supposedly has all kinds of benefits.

I am not claiming this and don't have a reliable source to point to.

My understanding is that it’s extremely hard to get large scale controlled studies on sun exposure vs vitimin d supplementation, so there is lots of uncertainty still on relative efficacy. I wouldn’t say certainly that it’s inferior to sun exposure, but sun exposure can clearly have many more effects than just stimulating production of vitimin d that could then appear to correlate with D serum levels.

Some more reading specifically on vitimin D:

https://ods.od.nih.gov/factsheets/VitaminD-health%20Professi...

Can't find it now, but this is probably based on a study/studies that I've seen that showed that lack of vitamin D is correlated with bad things, but supplementation doesn't fix the bad things nearly as much as you would expect. So, the idea some people have is that vitamin D is merely a correlate of something else that sun exposure does. I call it "sun magic" :)

...sometimes I secretly wonder if sunscreen (over-)use in America would one day be found to be the cause of rise in depression and other things like that over the last few decades, kinda like lead pipes of old. I don't think it's likely but it would be kinda funny.

Yes, I sometimes feel like I'm at death's door when jogging outdoors. Myself and some Westerners I know haven't "adapted", even after years being here. The strategy is just always have ice water in hand if outdoors for prolonged time. I sometimes get laughed at for not adjusting to the heat, but I think it's just too much for some genetic lineages from outside tropics.

Unfortunately a large percentage of folks in HDB flats don't have AC, so I do fear for many citizens in Singapore. With global warming trends it should simply be a free or heavily subsidized utility here.

I've been thinking about this, and it's seeming like childhood exposure to prolonged heat and humidity may be what gives you the ability to handle it as an adult.

It's just an anecdote, of course, but there are notable examples of people i think should be from genetic backgrounds that could handle the heat that can't, and vice versa.

Without a reference handy to back this statement up I think there may indeed be epigenetic changes. Perhaps even more pronounced would be the experience of the mother in hotter environments during pregnancy.

After a car accident, I had to depend on public transport in the boondocks where my job required shuttling from site to site in very humid hot tropical weather. I thought I was going to die that first week.

One of the locals finally told me I couldnt just walk out of airconditioned low humidity offices into the street and roam around, without giving my body 10-15 minutes to recalibrate. So before setting out from air conditioned buildings, I would stand outside in the shade for a bit and then head out. And that made a big difference. I started sweating less and didnt feel humidity as much.

I used to work construction and when I was a teenager I worked on farms growing up in the rural South.

If you work outside all day you adapt very quickly to it. During the adjustment period you are chugging water all the time but you eventually adjust. It's a circulation adaptation that's been observed with special forces recruits.

> If you work outside all day you adapt very quickly to it.

Sort of yes, sort of no. In some industries, those who do hard labour in heat have a terrible death rate from kidney disease. There is a lot in the news about this in relation to sugarcane workers. Eg: https://www.theguardian.com/world/2012/oct/14/kidney-disease...

When you use AC during nighttime you never get adapted to the heat. Try slowly phasing it out.

That's contradictory to leading sleep scientists like Matthew Walker, Peter Attia, etc. which is clear about need for chilly environment for sleep quality, eg < 21C. Granted, sleep science isn't oriented towards the genetics of the tropics yet, but there's plenty of evidence about temperature and sleep quality for more northern genetics anyway.

I agree with the parent. Killing the AC for weeks on end really helped me acclimate to the local temperature.

I'm not saying it resulted in quality sleep (as a Canadian - I set the thermostat to 13 degrees in the winter when sleeping, and my ideal temperature in the summer is about 18 degrees) - but you get used to the outdoor climate reasonably quickly (in my case, about 4-6 months).

Is 18 degrees assuming a fairly warm duvet covers / blankets? When I was staying hostels the dorms would sometimes be air conditioned and only a sheet would be provided for cover, and I struggled to sleep in anything colder than 21, and I'd have had it up to 22-24 if I could.

Sort of - now that I live in Michigan, and re-acclimated to a northern climate, at 21 I have to sleep on top of blankets or I overheat (though, I will find that after a few hours, my body cools down while sleeping and I may pull a blanket overtop me). 18 + a normal duvet is perfection. Cool enough for blankets, but not so cold that I feel uncomfortable.

This is mostly a meditation on the fact that I used to be able to sleep in temperatures of 26-27 in Singapore. The human body (at least this one) can definitely acclimate to local environments given some time and exposure.

Of course - no acclimating whatsoever will help you if the wetbulb temperature gets up to 35. You are just dead unless you can find some active cooling at that point fairly quickly.

I don't think it is contradictory - that is the point of adaptation that you expose yourself to something that is not optimal and your body learns to handle it. Think of it as artificially changing the range of conditions needed for good sleep quality by training.

Weird. I slept just fine in 27-28 for years. Unless I had a cover anything cooler than that was uncomfortable.

Stop it with the genetics talk, unless you want to cite some research.

https://guzey.com/books/why-we-sleep/

I'm in Denmark, when it gets 26 degrees here I drench my shirts in ice water and put in the freezer for a bit and then put on to cool down. I'm guessing, given what a wimp I am about the temperature, a few more degrees and I'm one of the first to die.

Always look on the bright side of death.

I'm thinking you must be Danish because of the Monty Python joke - Danes love that damn movie.

Unfortunately it looks like someone who didn't get it downvoted you. Welcome to HN!

I've lived in Australia and Norway. Your body adapts to ongoing temperatures. In Norway you're taking off your jumper as heads into double digits entering spring time. In Australian summer your putting on a jumper at 22 if there's a cold summer night.

We've literally be talking to Norwegian family about their nice 22 degree day at the beach while I was loading the fire place, they asked me the temperature, checked and was 22 also, though would have dropped later at night.

I find over 35 gets tough to do ongoing outdoor work. An hour or 2 then you need an hour or 2 to cool down. Hitting, 40c this is getting too hot.

Yeah, people don't understand that the human body is remarkably adaptable. Just need to stay in a place for a while (a few weeks to months). I've cycled to school ~10 kms everyday in 35-40° as a kid, came home to cool down instantly under a ceiling fan. Now in my current city I find 27+ too hot.

Big factor is body fat, when I was very skinny I could take higher temperatures than 40pounds later. It made basically 5 celsius degrees difference of "quite nice and warm" vs "too hot to operate" temperature.

https://data.gov.sg/dataset/wet-bulb-temperature-hourly?view...

The Changi airport weather station does not have any recordings of a 35C wet bulb temperature. And this paper suggests that it is a very uncommon occurrence as yet. What source are you using?

https://www.wbgt.sg/allstations

That is wet bulb globe temperature, not wet bulb temp. WBGT is calculated by adding together weighted WBT, globe temp and dry bulb temp.

See: https://www.instrumentchoice.com.au/news/wet-bulb-temperatur...

Yes sorry I shouldn’t be conflating two different concepts. Wbt >35 is the fatal temperature. Wbgt black (>31-32 depending on source) is where physical activity is dangerous.

Having lived in Singapore for five years (2012-2017) (and worked out in the field for about 50% of that time) I can say that Singapore is one of the milder places to live. It never ever gets particularly hot (I genuinely can't recall a 100+ degree day in the entire time I was there), and the humidity, while, "sticky" is never really extreme. The thing that gets to you is that the climate never seems to change (with the exception of a lot of rain) - it's always pretty humid and in the high 70s/low 80s, 24x7x365.

Once you acclimate to it though - it's fine - I used to do a 5 mile run every day from Anson Road/GardensByTheBay/MBS - wasn't an issue.

I worked in Dubai for about 6 months, and there were days there that I honestly thought I might die if I didn't get somewhere cool. And it wasn't the days that were 115 degrees Fahrenheit (46 Celsius) (though those were intense) - but the 100-105 degrees at super high humidity that would knock you on your back. Your entire body would be instantly bathed in sweat and it wouldn't help.

I was fine without Air Conditioning in Singapore - would sometimes turn mine off and just open the windows, but I can imagine anyone doing that in Dubai during the hot season.

> I can say that Singapore is one of the milder places to live. It never ever gets particularly hot

Singapore is almost exactly on the equator. UV readings get up to 11 each day (extreme), whereas the most I ever saw in say SF was 5.

Your experience is one experience, mine is that it's a sauna every day of the year. I've experienced extremely hot days in terms of subjective experience of WBT as explained in article. My gf, a local here, also decries the heat. I personally cannot go running before 5:30pm. I got a major sunburn on my back at 5:30pm the time I tried running shirtless at east coast park. Granted, I am pale.

But what are you comparing it to? Anywhere tropical (or even mediterranean) is going to seem hot compared to SF. Not being able to run until the evening and getting sunburn at 5.30pm are standard in a mediterranean summer too

As a fellow Singapore resident, it's undoubtedly hot. The parent's point was that there are places like the Gulf that are unquestionably hotter.

I once visited Kuwait in August, and it was 52 degrees in the shade with near-100% humidity. I genuinely do not understand how some people survive there today without aircon, much less how they will do so if temps go up a few more degrees.

But it is also close to the ocean which is usually much more livable than anywhere inland in Malaysia or Indonesia.

" the most I ever saw in say SF was 5."

Really? London is 6 today, was 7 last week and 8 earlier this year.

I do also concur with the GP that Singapore is relatively mild as far as equatorial/tropical climates go. India, the Middle East, the Philippines and even Australia are sometimes much more oppressive.

The hottest day ever recorded in Singapore was 37c, whereas London is 38c and SF is apparently 41c. Of course, Singapore is more humid (and thus higher WBT) - but it's also much more consistent. In theory that would make it easier to acclimate..... but then Singaporeans seem to run their AC set to freezing.

It is unintuitive, but equatorial locations are usually stable and relatively moderate. They will tend to be uncomfortably warm year round, but never experience the temperature swings of locations much further north or south.

https://images.app.goo.gl/P4YtYRLvT5XVcn168

Look at this map of max temperatures and note that the equator runs through a band of relatively low max temperatures: Indonesia, northern South America, and the more southern part of Africa show bands of conspicuous coolness. The hottest max temperatures are in places like southern North America, India, Northern Africa, and Australia; locations that are in fact very far away from the equator.

The max temperatures of a place is caused by many things, such as proximity to water and local wind currents, but one driving reason is relatively simple: because of the tilt of the earth, every day on the equator is 12 hours. North or south of the equator, on the summer solstice, you can get 15 hour days, depending on latitude. The summer is a period of continuously intense solar heating. Again, there are other factors, but the sun is the driving force.

San Francisco is slated to just about hit 10 today.

Living in both San Diego and now Denver, they hit 11 quite regularly.

Singapore is also really cloudy. Definitely not "Sauna" like Dubai (or Washington DC on a bad day) - but non-stop "Sticky". I was always wet, but would work outdoors for 4-6 hours/day doing field survey work across the entire island.

In the time I spent in Dubai (about six months) in comparison, I had to seek shelter from the heat/sun a half-dozen times, and came close to heat-stroking a bunch of times. That was after 4+ years in Singapore.

I drank a lot of water in Singapore - but never, in a million years would I have gone on a trek like MacRitchie reservoir in Dubai - and in Singapore I took my 65 year old mother through the entire loop.

Just completely different environments - Singapore is not the type of environment being discussed in the original article.

Little pedantic, but you meant "Wet-bulb" temperature (https://en.wikipedia.org/wiki/Wet-bulb_temperature#Temperatu...).

I only know from owning a swamp cooler.

It is worth correcting, because I think most people haven't heard of wet-bulb, just as the methods and formulas that give us humidex "feels-like" temperatures aren't common knowledge.

A lot of ways we measure and describe the human experience of humidity and temperature are not standardized from location to location, so the non-local methods and terminology can be arcane for anyone who isn't a meteorologist.

I never heard of wet-bulb temp until carrot weather included it in a recent update.

Isn't it basically the same as the dew point temperature? I believe a lot more people are familiar with that.

Just looking at the graphs, dew point temperature tends to be a bit lower than the wet bulb temperature (when humidity is equal).

No, dew point is the temperature of an object on which air will start to condensate (because cooling the given air to the dew point lets relative humidity rise above 100 %, i.e. condensation). Wet-bulb temperature is the lowest temperature an object can reach through evaporative cooling (i.e. humans).

The two are the same only if relative humidity is 100 %: 100 % relative humidity means that if the air cools at all, it will condensate; so the air temperature is the dew point. 100 % relative humidity also means that water cannot evaporate, as the air is already saturated with water, so the wet bulb temperature is also the same as the air temperature.

But that's the same isn't it, because condensation is a reversible process, as evaporation. At some point they will balance, and this is the dew point.

Yes, that's right. I did mean wet-bulb. Not sure why my brain didn't register this mistake when I wrote it.

I find it amusing that people are trying to downplay this because it is feasibly survivable in their opinions. If you're wondering "how I can survive these circumstances in my own home?" things are already really, really bad.

95 Fahrenheit is actually quite survivable. It is dangerous for old people, young people, and the very sick when combined with sun exposure and other factors.

I spent much of my life living in that temperature range without A/C, working outside during the day in the sun.

It's hot but not going to kill you. In fact, there are massive homeless encampments outside my window right now in extremely humid, hot, Texas weather (it is 95-97 all week and very human). The homeless have endured many summers like this.

It is a massive stretch to say these temperatures are not survivable. They are not healthy in the long run - but neither is sun exposure.

It's an incredible exaggeration to say Chicago (where 600 people died in the heat wave) is not survivable at all when millions actually did survive the heat wave without AC.

They're talking about wet bulb 95 degrees which occurs at somewhere around 130 degrees of open air temperature. You have not spent much of your life at wet bulb 95 degrees.

95F in dry air is not the same thing as wet bulb 95F. That is the majority of the discussion being had in other threads.

Critically, not just 'dry air' vs 'humid' in the human sense. Wet-bulb is temperature at 100% relative humidity. A 'humid' day in the human sense is like 60-70%.

35 wet-bulb temperature is not survivable. That is not a matter of opinion, it is a fact. Your body generates heat and at that temperature it is unable to shed it through any means and you will die in a couple of hours.

If a major city has such a heatwave, it will almost certainly be a mass casualty event, mitigated only by the duration of the wave and how many people have A/C (or how long the blackouts last).

A fan won't work because your sweat will not evaporate: in fact it just heats you up faster (like breathing on your skin in a sauna).

Such temperatures have only been measured a few times on earth, so no, you have not experienced them.

N.B. the 35c/95f temperature they're talking about is _not_ air temperature. It's 'wet bulb' temperature, or what the air temperature would be at 100% humidity. Only when the actual humidity is 100% are the two equivalent. Otherwise, the wet-bulb temperature measures the lowest temperature achievable by evaporative cooling. The survivability concerns of sweat being unable to cool humans below hyperthermic levels should be obvious.

At quick check, humidity in Houston is like 55%, so the wet-bulb temperature is only ~80f. Uncomfortably hot, but not close to the threshold discussed in TFA.

Good to know. I should not have skimmed the article before replying.

For people reading "web bulb" here and not having the least idea of what it is, first of all it's "wet bulb", and this article explained it very clearly to me:

https://www.iflscience.com/environment/why-is-everybody-talk...

Seems like Wet Bulb is a more precise version of what some weather reporters call "Heat Index". Meant to measure how hot it actually feels on the skin. Is there any sort of formula mapping heat + humidity to wet bulb?

https://www.omnicalculator.com/physics/wet-bulb

In Canada we call it "humidex" because we're cool like that.

Genuine question: does old-style insulation not help? From when I was a kid I remember that a log house built using 60ies village technology (realistically probably more like 19th century technology), insulated with something stuffed in the triangles between logs and wallpaper and logs and planks (and partially eaten by mice ;)), stayed pleasantly cool on 90-degree days. And the dugout under it that we used to store potatoes and stuff like that was actually cold.

In a recent Seattle heatwave, when it was 107 outside my much poorer insulated semi-basement with direct sun shining into its large-ish windows, stayed under 85 without AC.

Couldn't people just build better / underground housing using relatively primitive technology?

Eventually it'll be hot enough outside that the "cooler" inside is not cool enough without air conditioning.

This is temperature of air (big amplitude) vs temperature of ground X meters undergrounds. If you go deep enough it doesn't matter how hot it is outside - the temperature is basically constant the whole year.

http://www.rynekinstalacyjny.pl/images/photos/24/3877/__b_An...

I'd bet that data is from sensors with low heat dissipation. Unfortuantely, humans produce ~100W of heat each. If you're using a small underground basement as a place to escape lethal heat aboveground, or even a large underground basement with high people/m³, this added heat will steadily increase the basement's wall temperature.

The rate of temperature increase depends on physical properties of the basement walls: using the first equation here[0] as an approximation, set x to 0, set q"_o to 100W*(# people)/(basement surface area). α is the thermal diffusivity of the wall material [1].

[0] https://slideplayer.com/slide/1676039/7/images/9/Semi-Infini... [1] https://en.wikipedia.org/wiki/Thermal_diffusivity

We already see 35c wet bulb temps in parts of India. It's deadly.

A lot of new technology could potentially solve this problem.

There are certain types of roofs being installed called cool roofs that reflect heat and don’t absorb it that keeps the inside of building a little cooler.

Radiative cooling roofs, like those from sky cool systems actually cool your house during the day. I'm not sure how cost effective those are but the technology seems to be very promising.

Those radiate through the atmospheric microwave window, right?

Yep! Looks like the authors of the first paper I read on it (glass microspheres in silver-backed clear plastic film) are finally starting to commercialize it too... http://radi-cool.com/technologies/

Also air conditioning

For people who can afford new technology. For hundreds of millions to billions of people that's not an option.

Imagine a future where looters drive through wastelands where heat waves killed off the entire human population, dead bodies rotting in the street, and the looters rummaging through whatever valuables they find, exchanging occasional gunfire with a survivor or rival clans.

That’s the climate changed world.

Small questions, Arab countries used to build cooling towers a few centuries ago. Would that help for countries you were thinking of?

I started reading it and it’s the most grabbing and realistic writing on climate collapse that I’ve encountered to date.

The prediction of how people react to the changes - from individuals to institutions to governments is spot on.

Highly recommended.

I challenge anyone to read that chapter and not be moved. Absolutely brutal, visceral writing.

> everyone living under such a heat wave will likely die.

I mean ground and buildings have thermal inertia, if the heatwave is relatively short you can survive in basements or underground parking. Also water in the pipes will still be colder than the air most likely.

If there’s a heat wave and drought the only way is to dig tunnels and build cities underground. Water can be imported from the ocean (rising sea levels) and desalinated using solar/thermal power above ground and feed an aquifer!

On a purely technical basis that may seem reasonable.

On a "we're talking about human beings here" basis what do you do about all the people who feel that the selection and admission process was corrupt and that they've been robbed of their chance at safety? Do you expect them to meekly acquiesce?

I imagine once the first big wave where a nation hits the wetbulb temperature and there is a mass die off you will see panic in surrounding nations and they will scramble to a border. What will nations do with millions of people knocking at the fence wanting in? Uncertain times for sure.

I imagine this happening only in the least well-run countries. In any country with a functioning military, they'll probably organize a mass operation of moving people into temporary refugee camps in cooler areas of the country or into caves, underground structures etc. For people who won't be moved, they'll provide food and water for them so that people don't need to leave their hiding places during the day. (Also, I suspect that, after first major killer heat wave hits an area, people will have their own contingency strategies - be it digging a cellar for themselves to stay in, move to relatives in cooler areas for the duration etc.). However, I'm not sure if for example India is organized enough to pull this off, given their absolutely massive population.

The countries that will be most affected generally don't have well-run militaries either. We're talking about places like Bangladesh and El Salvador.

It’s going to be a global scale “north versus south” war like in South Park—everyone will blame Canada… and Satan will… err never mind. :)

I'm always a little surprised the islands in the Canadian archipelago never seem to be sold.

What is actually going to happen is displacement. The hundreds of millions of people most vulnerable to the consequences of climate change don't have much choice but to start walking. The 2015 refugee crisis in Europe was nothing compared to that, never mind the tiny trivial inconvenience that is current illegal immigration across the Mexico–US border.

Agreed. Europe struggled to relocate 2.5M of refugees over several years.

What happens when people from India, the middle east, ... are forced to relocate? I expect some kind of conflict/war of expansion and probably famine since a lot of the land will be abandoned and hence become unproductive.

I'd expect the land to become unproductive first. A huge amount of agricultural land is threatened by the climate change, accelerated by other anthoropogenic effects such as soil erosion due to deforestation. Besides drought, heat, wind, and excess rainfall, there's flash floods caused by melting glaciers in the Alps, Himalayas, …

True. And at that point I really believe unrest will be widespread. The saying "We are 3 meals away from anarchy" will prove its veracity.

I think Bangladesh is also scheduled for certain crisis.

And let's be real, no wall (or frontex and the like) will ever keep out billions of people. If the world doesn't get its shit together and respond globally and collaboratively now, this will get ugly beyond imagination and no one, no matter the edgy coldness of their x-first attitude, will come out of this recognizable. People won't just die politely, much less when informed about who's to blame for all this hell.

I think there may be even possible consequences beyond everyone's worst nightmares when we see massive ecosystem collapses. What is it gonna be like, if you have unimaginable fields of mold and bacterial overgrowth? The winds bring Sahara's heavy mineral dust to Europe now, I am sure spores and toxic particles fly much better tomorrow...

"The study — published in the British journal The Lancet — analyzed data on more than 74 million deaths in 13 countries between 1985 and 2012. Of those, 5.4 million deaths were related to cold, while 311,000 were related to heat."

Study: Cold kills 20 times more people than heat https://www.usatoday.com/story/weather/2015/05/20/cold-weath...

Do you think that having more extreme weather events will reduce the number of weather related deaths, or increase them?

Deaths from natural disasters are at or near civilizational all time lows on a fractional basis of the population, see quote below. This trend in lower deaths should continue. It is not clear to me that we are experiencing more extreme weather events than 100 years ago. We haven't had anything like the Dust Bowl (1930s) or the Great Chinese Famine that killed 45 million (https://alphahistory.com/chineserevolution/great-chinese-fam...) or the Chinese Famine of 1907 that killed 25 million (https://www.bartleby.com/essay/The-Deadly-Famine-And-The-190...). Or the Bengal famine or the Vietnamese famine of the 40s. Or the Yangtze flood of 1931 that killed 2 million. Or the Bhola cyclone of 1970 that killed 500K (https://en.m.wikipedia.org/wiki/1970_Bhola_cyclone)

"What we see is that in the early-to-mid 20th century, the annual death toll from disasters was high, often reaching over one million per year. In recent decades we have seen a substantial decline in deaths. In most years fewer than 20,000 die (and in the most recent decade, this has often been less than 10,000). Even in peak years with high-impact events, the death toll has not exceeded 500,000 since the mid-1960s.

This decline is even more impressive when we consider the rate of population growth over this period. When we correct for population – showing this data in terms of death rates (measured per 100,000 people) – we see an even greater decline over the past century. This chart can be viewed here."

https://ourworldindata.org/natural-disasters

Your confusion is caused by conflating two effects: the reduction in impacts from extreme weather driven by improved technology and scientific knowledge, and the increase in impacts driven by an increase in the frequency and severity of extreme weather events.

The reductions you discuss are attributable to the first of those two effects. Climate change drives the second. If we mitigate climate change then we can spare ourselves the increases attributable to the second effect.

You may reply that the first effect can always outpace the second, but I hope with some thought you can recognise that there is no evidence to support that claim, and it is essentially just an article of faith.

People are unlikely to start a mass migration from traditionally cold climates, but it is very likely that a mass migration will start when densely populated regions become lethal a couple of times a year.

I wonder if going underground can help (being realistic that we are not going to make any drastic CO2 related changes)

I wonder how practical it would be to sink 30 foot deep concrete tube shelters with a ladder and a lid. They could serve as emergency daytime shelters and someone could climb out at night to search for a location with working power or cooler weather.

There'll be issues keeping that cool and the air fresh putting enough people into them. Also some of the most endangered places have huge populations that would make sinking enough shelters difficult. Depending on the soil composition that might be a short term solution too. The soil surrounding the London Underground is particularly bad for this and it's estimated that 80% of the heat ever generated in the Underground is still there in the walls.

https://www.youtube.com/watch?v=hQo6_GkITe0

Not practical on any Pacific island sitting just above sea level.

Sit in the water instead? The ocean water tends to be cooler than the air due to oceanic currents.

Excellent point. Woods not seen for interfering trees.

If mankind has to start living at night because daytime is too hot, at least night owls will no longer have to shorten their life expectancy to fit into a daytime schedule.

Welcome to Spain.

itd make more sense to lay a bunch of pipe underground and cycle air through it. or water in a closed circuit with a heat sink.

If you have power you can just use a heat pump like a window unit. This is about places with unreliable or negligible power grid.

I do wonder, if wet bulb temperature is a function of temperature and humidity (assuming reducing temperature requires electricity usually) will the real trick to reduce mortality will be to reduce relative humidity in a confined space. A supply of emergency desiccants somewhere at home may be an avenue worth exploring.

This was the original application of Air Conditioning: to reduce the humidity of air inside a building.

I suppose the best available option for a lot of people if designated shelters aren't available would just be to walk to the nearest body of water and climb in, and wade around until the heat subsides.

You're assuming the nearest body of water is somehow cool enough, which is often not the case.

Well, you'd have to take it on a case-by-case basis. I suppose as long as the water is at least somewhat below hot-tub temperatures it might be a reasonable way to sort-of cool off.

If the water is still running - can't people spend a lot of time in the bathtub?

It only works if the water is cooler than the ambient air. A bathtub full of water will warm up to ambient at some point and won't be as effective after that.

In the locations this happens, does everyone : have access to a bath (one per family member), running water (in a city were everyone is running a bath at the same time), a job where the aren't forced to go out and work every day to survive?

What will the vegetation and animal life look after such a heat wave? Mad Max desert?

Or are they so much better adapted that it won’t be a problem (I don’t think so)

It’s not just about adaption, many animals in hot climates burrow which provides a cooler place to rest than above ground housing.

As an aside, would you recommend that book?

Yes... But the first chapter the OP is talking about is truly horrifying, I honestly wish I hadn't read it. His other book New York 2041 also deals with climate change and is less traumatizing.

Yeah, there's so much unavoidable negativity around, so when I have the chance to choose I'd rather focus on positive things and read/consume things that make me happier instead of depressed.

Especially in terms of climate change. I try to live as green as I can and I vote for a climate focused party, other than that there's not much I can do as an individual. Reading about how bad things may become doesn't help me one bit.

Something else you can do as an individual is teach others about certain physics concepts that are massively misunderstood such as how air conditioning and heat pumps work.

Ask a layman and most of them will tel you a fridge just “creates cold” or something and don’t understand why leaving the fridge door open is not a way to cool your room.

Having people understand these concepts is critical so they can better reason about climate change, climate policies, make better and greener decisions etc.

I made the mistake of starting to read this before going to sleep last night. Terrifying.

oh OK, so no one will do anything about it and it's probably gonna happen and when it does it will be. out of the news cycle in a few days. noted.

This feels like one of those prescient HN comments that are cited in the future. IDK, just... replying to say I was a witness too.

Wet.

It’s called wet bulb, not “web bulb”.

A mass death event will likely happen in a city with 26 million people that most folks outside China aren’t aware of the danger..Shanghai. Shanghai has been having extreme heatwaves, the worst one in 2017 where the temperature went to 46 degrees. Shanghai is projected to be unlivable in this century.

I’m not sure if it’s an issue specifically around Shanghai, but electric power has been unsteady in China at large. An energy crisis during a heatwave could be indeed deadly, especially with the ambient temperatures of city life. I’m bullish on Chinese acumen for major infrastructure projects and I’m sure they will adapt, but that seems like a crazy costly set of projects. At this point ultrawhite paints look promising.

> especially in poor tropical countries that don't have a stable infrastructure to cool most people during such a heatwave

Like California? They already can’t keep the lights on with rolling blackouts happening every year. If one of those blackouts happens during a severe heatwave, it could be serious. Not to mention the serious economic cost of having a third-world quality grid in what should be one of the union’s most prosperous states.

I think California's air is too dry to get to the wet-bulb temp limit.

For now. I was seeing temps pretty close to 120 last year. It was dry, but who knows how the climate will change either the humidity or the high temps. 130+ doesn’t seem inconceivable and that gets pretty close to the limit.

I have travelled to two countries where heat can hit that temperature, and they do not have the luxury of any AC, or in some cases even a fridge.

A few cities around the world do reach 35 or higher regularly during summer. And in a some of those people have lived for thousands of years.

https://en.wikipedia.org/wiki/List_of_cities_by_average_temp...

Wet bulb temperature is not the same as average temperature. See https://en.m.wikipedia.org/wiki/Wet-bulb_temperature

Here is a decent visual explanation of the relationship with relative humidity: https://digitalcommons.unl.edu/cgi/viewcontent.cgi?referer=&...

Edit: didn't know about wet-bulb temperatures (was confusing it with perceived temperature). Here is a link for a wet-bulb temp. map: https://meteologix.com/th/observations/701-e-263-n/wet-bulb-...

I think you don't understand what wet bulb temperature is.

Wet bulb temperature is a combination of humidity and temperature.

Wet bulb temperature of 35C means your body physically cannot get rid of heat and you WILL die, rather quickly, even in shade. There is no escape unless you have ability to control humidity (ie. remove some humidity from the air).

Up until recently we did not have situations on earth where wet bulb temperature would reach 35C. Even in the most hot places the air would be dry enough to bring wet bulb temperature down under 35C meaning, things can cool below human body temperature.

The issue is that a lot of people in hot places simply do not have the means to control their climate in their houses, assuming they have any.

I think we know based on the science we’re not going to see a stabilization in temperatures for at least 30 years under the best scenarios. We should focus on ways to save these lives. Solar powered swamp coolers is what is I’m thinking about. They require water however and that’s going to be as big of a problem as heat. Already is in many places.

Swamp coolers cool based on evaporative cooling: water evaporating into dry air reduces the (dry bulb) temperature of the air. So with high wet bulb temperatures indicating air is already saturated with moisture, the swamp cooler won't work.

Dehumidifiers are a thing. I presume that having water and electricity is a bigger problem for most people, but I’d love to be educated more on the problem, if you have links or literature.

Dehumidifiers are air conditioners that put the heat back in the air they treat instead of dumping it outside. Your electricity would be better spent operating a real air conditioner.

Or you could use an Einstein-Szilard (aka absorption) refrigerator that works without electricity. It’s driven by heat. It uses 3 gases (butane, ammonia and water.) It has no moving parts so it’s safe.

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.

(Commercially available) Dehumidifiers are basically small air conditioners with both the hot and cold side in the same room. You can't run them without electricity, and if you can run a dehumidifier, you may as well dump the heat outdoors instead and cool and dehumidify your space.

Yes, but combining a swamp cooler and a dehumidifier is most of the way there to a modern AC unit, both in concept and electricity need.

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).

I'm dissappointed to see you're being downvoted for what looks like a good faith (and common) misconception with a request for more information.

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...

Swamp coolers do not work in high humidity. Running cool water from underground over oneself works, but is unsustainable and impractical. Going underground to someplace cool is also sometimes an option that does not require electricity, but is often impractical and highly situational.

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.

You could potentially heat up a dessicant to dry it out and use that indoors to survive the humidity without having to go underground or have AC.

Interesting idea, though I'm not aware of any desiccants that would be appropriate for the scale we'd need to operate at here. Silica gel, for instance, wouldn't work because there's too much water to handle. Dehumidifiers could be used instead, but they heat up the air as they dry it out. I believe desiccants also heat up the air, but only slightly. Maybe they would heat up the air a significant amount if they were removing enough water from it for this scenario.

Or.. Build more basements and underground shelters.

No, it wouldnt work as the heat would have nowhere to go. And the mid east people didn't do it - https://en.m.wikipedia.org/wiki/Windcatcher

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.

> Instead you build and live in highrise/towers

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.

Look no further than Dubai how to build highrises with good feat insulation, and cooling.

You can build ventilation or even just building houses with basements would help a bunch. The temperature underground is a lot more cool and steady and would help you escape the heat. There is a town in Australia that does exactly this because it's so friggin hot:

https://en.m.wikipedia.org/wiki/Coober_Pedy

Migration. Large parts of the taiga and permafrost are about to open up to human habitation. All the folks in the Middle East and India should move north in search of better weather.

Human societies have been historically very bad at handling large scale migrations, but it's about to become necessary.

I am sure this will cause no serious issues whatsoever.

there was an article during the recent Oregon heat wave by someone who moved to the PNW as a hedge against climate change. that heat wave killed almost 200 people and is estimated to have killed a billion marine animals.

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.

A million times this. It's important that everyone know that there's nowhere left to move to in order to continue ignoring the problem.

No place is going to be safe, but some places are going to be a lot safer than others. The PNW or Canada is a lot better bet than the Middle East or Bangladesh.

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.

Apart from all the other issues (societal, etc) with that the climate of Yakutsk[1] can give an indication of how hospitable that region is. Spoiler: It’s temperature span is over 100C (nearly 200F). Brutal winters, brutal summers.

Not saying you’re wrong, though..

[1] https://en.m.wikipedia.org/wiki/Yakutsk

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