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Comment by iknownothow | Hacker News Reader

Just a personal anecdote to provide some context of how hot it really is.

I'm from the south of India and now live in Europe. My body tolerates heat quite well compared to my European friends. I remember tolerating 38-40C indoor temperatures and sleeping through it with heavy sweating. But air temperature of 42C is where I draw the line. It is almost biologically impossible to survive this.

So this story isn't just about record high temperatures, it's about record high temperatures that coincide with biological limits. If air temperature reaches 44C, it's impossible to survive this without artificial cooling and I predict a state of emergency will be declared every summer starting 2030.

There's one additional factor. The hottest months in the equator are June to August. This happens to coincide with the monsoon season in India. So I remember dreading May but looking forward to the monsoon in June. If climate change messes with the monsoon season, the Indian subcontinent is f'ed.

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This is also known as the wet bulb temperature, and it is a function of the humidity.

https://en.m.wikipedia.org/wiki/Wet-bulb_temperature

If I were in a position of decision making in India, I would invest in large deployments of passive radiative cooling films: https://www.3m.com/3M/en_US/energy-conservation-us/applicati...

These reflect nearly all the sunlight energy and cool their surroundings night and day by controlled black body emmisive radiation. (interestingly, for cooling applications, per unit area they are more power efficient than solar panels + AC, because solar only is working during the day, whereas passive cooling films also work at night)

That doesn’t seem to line up with the marketing you linked. “10-20% energy savings when integrated with building refrigeration and HVAC systems.”

PV on the roof can normally provide 100% of the energy needed for AC.

It’s a per-unit-area comparison:

https://www.betonconsultingeng.com/passive-radiative-cooling...

“”SkyCool arrays work by cooling a fluid that moves below the panels and is pumped through refrigeration systems. The cooling helps reduce the run time of motors in the refrigeration system to reduce electricity consumption. All told, the SkyCool system can reject heat at about 100 watts per square meter, saving between 450 and 550 kilowatt-hours per square meter every year—twice the average production of a solar panel.—Brooks Johnson, Star Tribune, 12 March 2022“”

Ok, that’s your problem it’s about 2400Wh of heat moved per day per m2. A solar panel should be collecting ~1600Wh/day of electricity/m2, but an AC can then use that electricity to remove ~4,800Wh of heat.

And that’s assuming you need to remove heat 24/7/365. A solar panel can also provide electricity when cooling is unnecessary. Things get even worse if you need pumps etc to circulate a fluid under the film, which is presumably why that 10-20% cost savings figure was suggested.

Don’t necessarily need pumps, depending on what you are trying to do: https://www.abc15.com/weather/impact-earth/asu-testing-new-m...

This is what I was thinking of in the case of India :)

Edit: wanted to add, application of this technology might require government level systems thinking.

With an air conditioner, that heat being moved is being pushed to your neighbor, passive cooling technology rejects much of the heat out of the earth.

I.e., AC contributes to the urban heat island effect, the situation snowballs and makes everyone’s AC have to run even harder.

Passive cooling films are a mitigation for the urban heat island effect.

UHI is mostly due to the materials cities are made of and lack of evaporation from plant life which is why it was noticed 200 years ago. AC has such a small effect it would be hard to measure.

People are studying the effect. Passive cooling films get at the ‘materials cities are made of’ problem, by decreasing the city-wide absorptivity of heat energy.

“We found that waste heat from air conditioning systems was maximum during the day but the mean effect was negligible near the surface. However, during the night, heat emitted from air conditioning systems increased the mean air temperature by more than 1 degree Celsius (almost 2 degrees Fahrenheit) for some urban locations,”

https://news.asu.edu/content/excess-heat-air-conditioners-ca...

“By the end of the century, greenhouse gas emissions from air conditioning will account for as much as a 0.5-degree Celsius rise in global temperatures, according to calculations by the World Economic Forum.”

https://www.scientificamerican.com/article/how-to-prevent-ai...

First props that’s a peer reviewed paper so this may just be hot air on my part.

Anyway, their using the most extreme data that they can find to base their calculations which is rather suspect. They regularly mention 65% of electricity useable for AC, but that’s peak during a heatwave not the general average etc.

Still, a peak of 0.5-1C at night and ~0C in the daytime is a much larger effect than I was expecting especially when nighttime energy usage for AC is only averaging around 1W/M2 in their data.

> ...so this may just be hot air on my part.

Truer words were never spoken, no qualification needed.

So, yea 0.5 to 1C was taken out of context.

“To evaluate the contribution of AC systems on air temperature, the WRF AC100%, AC65%, and AC35% simulations were compared against the AC_NoOut experiment.” It’s even in the conclusion: “Sustainable development and optimization of electricity consumption in cities would require turning “wasted heat” from AC into “useful energy” which can be utilized inside houses for various purposes including, for example, in water heaters.”

In other words they simulated the cooling effect of AC without the heat produced by the AC systems entering the environment as the baseline. Not what would have happened if the AC had been turned off.

It is always a mistake to engage with this Retric. He just posts random remarks which do not stand up to a moment's scrutiny, but hopes they will seem plausible enough to derail meaningful discussion.

We have a word for that.

A wet bulb related crisis in India is used as a plot point in Kim Stanley Robinson's latest novel Ministry for the Future. The way he describes the wet bulb event is quite scary. (edit: corrected author and title, I confused this with Neal Stephenson's latest Termination Shock).

Imagine something like that happening in a slum. It's the combination of humidity, temperature and poverty that is deadly. Think mass casualties (millions of people). No air conditioned environments to escape the heat. Limited access to clean water. Flaky electricity systems that cause what little capacity there is to cool anything to fail. Temperatures at night drop a little but not by enough to provide much relief. Robinson does a great job of making you believe how real this would be and what it would look like.

The human body loses the ability to cool it self with 100% humidity. Sweat no longer evaporates. Basically, people start dropping like flies once that gets out of control. It's not survivable for more than a few hours. Any water you'd use for cooling no longer evaporates and would in any case have an ambient temperature that is close to or higher than your body temperature. Instead of cooling your body, it would just heat it up quicker.

This is a very near future science fiction novel that describes a very scary reality that we might be dealing with on a regular basis pretty soon. North West US and Canada actually got a sneak preview when temperatures in the US and Canada hit record highs last summer.

I thought the setup for that book was interesting, but it's probably his worst book IMHO (though I haven't read all of them). Normally I'm careful about attributing the actions of characters to novelists, but Robinson seems to be increasingly advocating terrorism in his books and it's getting really off-putting.

I agree, I did not actually finish the book. The setup was interesting but it was all a bit too moralistic and righteous for my taste. Neal Stephenson's Termination Shock is much more fun in that respect.

The terrorism aspect is interesting though. He's not the only one that is predicting conflict as a direct result of global warming. Mass population displacements due to things like wet bulb heat events, droughts, the middle east routinely hitting temperature of over 50/60 degrees Celcius, etc. have the potential to get really ugly.

There's an internally consistent moral argument that terrorism is warranted in this situation eg Malm's "How to Blow Up a Pipeline."

The basic argument is that peaceful protest is effective when it is an alternative to a more militant and disruptive extremist movement with the same goals. You negotiate with the peaceful side so the violent side doesn't tear your shit down.

When there is no extremist movement, you really have no powerful incentive to acquiesce to the demands of the peaceful movement. At this point mass peaceful climate protest is decades old but we've seen virtually no meaningful changes addressed.

We're tens or hundreds of thousands of deaths into the climate crisis and it's only just barely getting started and those with the most agency to change it very obviously have no intent to. Why is ecoterrorism considered a morally abhorrent line that cannot ever be crossed, but their choice is not?

The normative answer is "that is bad too they should stop" but by what means can we make them? Our options seem very limited.

I get what you’re saying but is the track record of terrorism any better at causing constructive change? Really we need to engage a lot of people’s minds, and that just turns out to be really hard in our current culture no matter what angle you come at it from.

No, what I'm saying is that understanding peaceful movements separate from violent ones is missing the point. For example martin luther king jr's peaceful civil rights movement was effective in part because there was a credible threat of a violent movement on its wing. There was conflict and cooperation between these movements, they can't be cleanly separated. A lot of the reason white people came to the negotiating table at all was because of fear of what would happen instead if they didn't.

Whose minds do we need to change? Climate change is a major issue with massive popular support. There are relatively few people actually able to take action on it and they will not under the current circumstances. Specifically because there's no credible non-peaceful consequence they have to confront, they can ignore the demands of everyone else.

The actual historical effectiveness of terrorism alone is questionable. It's not a reliable or sustainable way to change the minds of a large mass of people. But that's not actually what we need to do here. Making a powerful few frightened enough to do what they ought may be sufficient.

And the effectiveness of the credible threat of violence, combined with a mass peaceful movement, is well attested.

You should be placed on some kind of watch list.

Also, How many innocent people do you think you need to kill exactly to sway the CCP.

Again I will make this point, again and again. Here, today, on HN, in this comment section, we have people endorsing mass population culling of the most dispossessed people on earth, and the least responsible for climate change. How am I the moral transgressor for arguing, abstractly, that redirecting the harm towards those actually perpetrating it is preferable?

The CCP isn't my problem honestly. Most of the major contributors to climate change are operated from within my own country, so I'll focus on that. There's plenty of work to go around, I'm sure someone over there can handle that part of the project.

The fact that people can never really come up with anything except "but well CHINA" speaks volumes to me. You aren't rejecting this stance because you abhor violence. Climate change IS VIOLENCE. Where is your outrage, what are you willing to do about it?

But you have no solution, you just condone killing a few people in your own country because surely that will do something.

The fact that you can't even understand this is a global problem and just figure "someone over there can handle that part of the project" is telling.

You are a dangerous ideologue.

No one ever actually asked what my solution was!

My actual position is that there does need to be an extremist counterpart to the peaceful climate movement that can plausibly escalate to violence against people. But that there are several steps along the way with chances for those in power to de-escalate first.

Things like targeted destruction of fossil fuel facilities and harassment campaigns against certain politicians and executives are likely to be very effective at raising the cost of contributing to the climate crisis. If those with the power to actually respond to those measures do so, it won't need to escalate further. Hopefully violence isn't necessary but at this point unfortunately, the credible threat of it is.

> Hopefully violence isn't necessary but at this point unfortunately, the credible threat of it is.

The credible threat of violence doesn’t even work unless you can credibly threaten a huge portion of the population. Just look at how ineffective terrorism has been for the last 50 years.

Have you considered the civil rights movement was not successful because of the threat of violence but was instead successful because people actually changed their minds?

We have same sex marriage now, which was as unpopular as desegregation a couple of decades ago. When Obama went into office he was against same sex marriage. Society changed rapidly and without violence.

It likely changed so rapidly because it was not a coercive movement at all, but that’s just speculation on my behalf.

Mass murders in the US won’t help if someone isn’t picking up a machine gun in China as well.

You just said “not my problem”, which means you don’t actually care about stopping climate change. You need to stop thinking about how to kill locally when the problem is global.

I have to agree this is always the way I have understood every peaceful movement that has ever existed, the peaceful movements were big and there were smaller violent movements, it did not take an amazing inductive leap to think hey if we don't make some concessions sooner or later these peaceful folks are going to become violent like these others, and then there will be real problems for us.

Since India is also the start of this whole conversation Gandhi especially comes to mind.

Want to substantiate your claim that we're as many as hundreds of thousands of death into the climate crisis? Weather has always killed people, perfectly natural weather by the way, so if you're going to attribute deaths specifically to human-caused climate change, a source or two would be nice to see.

No not really. There is enough information that is easy to access that anyone who wants to can. If it's not convincing to you then changing your mind in this forum isn't a project I'm interested in right now.

No, there is plenty of models showing increased likelihood of various types of weather events due to extremes. Nobody has done meaningful analysis on deaths avoided or caused by these probabilities.

For terrorism to be morally justified, you have to be right that the alternative is millions of deaths. Have you considered the possibility that you are not right?

I mean, really considered? Not, my friends all think the same way, and so do the charismatic politicians I prefer, so it must be true?

You could start with your "tens or hundreds of thousands of deaths into the climate crisis" claim, which is highly dubious. Have you swallowed the false claim that hurricanes and tornadoes are worse now than before? Are you looking at net deaths, for instance counting not just higher deaths in heat waves, but also fewer deaths in cold snaps? And are you accounting for the beneficial effect of higher food production due to CO2 fertilization?

It would be hard for anyone thinking carefully about climate change not to have considered the possibility that they are not right, given the decades of relentless, well-funded industry propaganda making such claims, to which you have apparently fallen victim.

I think you've fallen victim to propaganda about how much propaganda each side has put out.

You're deep in it, aren't you? Oh well! The reality of the situation is already making itself obvious. Come out to the small coastal town I've spent the last few months in and try telling the people here that hurricanes aren't getting worse. Try to work out why everyone who can afford to do so has been getting their whole house lifted up off its foundation, onto stilts... But this place is not special, this kind of thing is happening everywhere. You can see it easily enough, if you let yourself look. Up to you. Can't blame you for wanting excuses to ignore it, though; the future we are barrelling along into is a scary place.

You know, people 200 years ago in coastal towns would have told you the same things. Flooding is worse, more bad weather etc. It's a terrible data point.

There is plenty of data that supports climate change, on a Global scale. Whether it kills millions or billions or nobody at all is simply a question of attribution.

Well, yes - you know that, and I know that; but I thought perhaps someone who can't accept the scientific consensus might find the personal choices made by residents of a conservative small town to be more relatable. Of course everywhere you go there are stories like this; whether people openly accept the reality of climate change or not, they are adapting, and you can see it wherever you look.

I've seen several publications in the last 5 to 7 years which suggest less nutrients in plants grown in higher CO2 containing atmosphere. For both outdoor and indoor. IIRC the useful nutrients are dispersed in more plant mass, which amounts to dilution. Why it is like that, I don't remember anymore.

Suppose that one thing you like to do in your leisure time is swim in lakes, which can only be done in summer. Now suppose that your work schedule changes, so that you have additional vacation time in winter, in addition to the leisure time you had before. Do you say, "Great! Now I have more time for leisure activities!", or do you say, "That sucks! The proportion of my leisure time that I can spend swimming has gone down!".

That's not how I remember it ;)

What I meant to say was less nutrients in same amount of weight/volume eaten.

He did a talk at the Long Now Foundation recently:

https://longnow.org/ideas/02021/11/10/climate-futures-beyond...

FWIW: he calls himself out in the talk on the lack of clarity between sabotage and murder.

> The human body loses the ability to cool it self with 100% humidity

I wonder whether there are practical/efficient ways of decreasing humidity in situations like this in closed spaces?

So that you could use a regular fan again to cool yourself by means of evaporation of water off of your skin.

An air conditioner already is a cooler and a dehumidifier. In a closed system, using a dehumidifier and then an evaporative cooler makes no difference. Assuming the electrical input to these is dissipated as heat, it ends up heating the room further.

> An air conditioner already is a cooler and a dehumidifier.

The cold heat exchanger coil can cause condensation, which dehumidifies, but if the air temperature is 'correct' the AC control thermometer will keep the AC unit off.

So you can have have an 'uncomfortable' environment because the temperature is 22C/70F but the humidity is >70%. This is why separate (whole house) dehumidifiers are often recommended: they have a separate hygrometers that cause the unit to start, regardless of what the temperature is.

Thanks for explaining, I didn't know about separate dehumidifiers used in addition to air conditioners.

Does the human body still depend on evaporating sweat to cool down at 22C? I'm trying to understand why one might dehumidify when it's comfortable at 22.

I live in a suburb of Delhi and to be honest it is not just the occasional days that it stays that high. This year it has consistently been above 40C since late March. Summer has just started and the hottest months are generally May and June. So, it is going stay like this for more than three months this year in all. Even worse is that unlike desert regions, even the night temperatures here stay above 30C many times during this part of the year. Sometimes you open the window at night expecting it to be better only to realize that a hot "breeze" is blowing.

Owing to the pandemic, I had spent the last couple of years in the foothills of the Himalaya where the temperature rarely went beyond 30C. It has been really hard coping up with the heat as it literally sucks the life out of you.

Ref: https://www.accuweather.com/en/in/delhi/202396/april-weather...

> If air temperature reaches 44C, it's impossible to survive this without artificial cooling

Humidity is the other key factor though.

When younger I remember a day of walking all around Phoenix for many hours on a day where it was 122F (50C) and while it felt like being inside an oven, it was ok because humidity was close to 0%.

But high humidity with high temperatures is what makes it unsurvivable.

I grew up in Las Vegas where summer would hit 120-124 F. Very dry heat. Sometimes in August it would rain for a day. Then moved to Arizona where it would hit 125 F once in awhile. Melt your brain.

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