> fatal even to fit and healthy people, unclothed in the shade next to a fan;
This is scary, what's a good way to survive for someone that doesn't have access to a bunker or AC? Immersing oneself in water in a bathtub?
This is scary, what's a good way to survive for someone that doesn't have access to a bunker or AC? Immersing oneself in water in a bathtub?
But in a detached demographic sense: effectively everyone lives in a city in the modern world, and while their housing might not be air conditioned most of the major buildings are. In an emergency like this everyone would just crowd into office buildings and shopping malls.
That's not to say this wouldn't be horrifying, but it's not the kind of existential social crisis people tend to imagine. Cooling ourselves down in a heat wave, in the modern world, is a solved problem at least as far as keeping ourselves alive goes.
The states of Rajasthan, Madhya Pradesh, and Uttar Pradesh lag the rest of the nation in economic development. This statement is very much not true in those places, and even elsewhere in India. Air-conditioning is still a luxury outside of relatively well-off people's houses, corporate buildings, and malls.
> Cooling ourselves down in a heat wave, in the modern world, is a solved problem at least as far as keeping ourselves alive goes.
People there can't afford to not work. Sitting in an air-conditioned space for half the working day 4 months a year is not viable for them. A lot of the work is manual or farm labor that must necessarily be done outdoors.
Not saying that #climatechange isn't an emergency; but people won't suddenly die.
Unless these buildings are designed as emergency shelters for heat waves their air conditioning systems won't be able to cope with all the people.
This makes me want to go live in a deep cave somewhere :(
The principal human-appreciated effect of AC is the dehumidifying of the air when it's cooled.
The dry interior air allows human perspiration to regulate temperature effectively. The AC doesn't have to cool all the bodies, it just has to keep the air dry enough.
In a scenario where you've filled the place with people, the interior humidity is going to exceed that of the exterior air and you'd just start dumping the moisture outside exchanging with the fresh, dryer air. It's a comfort regression sure, but not a everyone dies situation.
The survival of the people doesn't come down to the AC heat pump keeping up, it comes down to supplying them enough water to drink and disposing of the humidified air.
My point is just that it's the relative humidity that matters, and the AC system has some options there. I've lived through a desert summer in a small space without any AC at all. I'd just keep the windows closed as deep into the day as possible riding out the night's cooling until the air gets too humid indoors from sweat and respiration for the fan to have any cooling effect. At that point I'd open the windows for relief. The air coming in was usually much hotter than the interior air, since the space was well insulated and nights get cool, but it didn't matter because it's very dry air and perspiration resumes functioning. The situation is easily survived unless you run out of water for your person.
Of course if the outdoor air is something like 100% humidity there's only the heat pump option, but that simply doesn't happen in deserts when it's hot out. It's a desert, not the tropics.
In the desert the relative humidity shoots up when it cools down, the humid nights are the worst. But it's because they cooled down. Again, not a survival problem since it's not that hot, just uncomfortably muggy. One saving grace with deserts is they don't generally have any mosquitoes, so these humid nights can easily be spent outdoors without any annoyance.
That's equivalent to opening a window without the AC doing anything. If that would work we wouldn't be in a "crowd everyone into a shopping center" type situation, the people would be just fine outside in the shade.
> It's a desert, not the tropics.
While half of India is in the tropics, this part indeed isn't. But next month the monsoon will put humidity at approximately 100% [1].
1: https://en.climate-data.org/asia/india/delhi/new-delhi-30/
Even when the air temperature at your fresh air intake is cooler than the air at your condensor coil? Wouldn't we assume no system would draw its fresh air from near the condensor coil?
You still have a heat pump in the system, and there's a temperature difference between the air inlet and the pump outlet.
Specifically the ambient indoor air heat is absorbed by refrigerant which is transformed into a superheated vapor saturated with moisture. When this vapor either touches a cooler surface, or has cooler air blown past it, it will dehumidify and exhaust the heat it has absorbed indoors to the outside. The mechanical work done by the AC (fans, pumps) is also being released as heat. So the total energy being dumped outside is therefore the heat that's taken from the inside plus the energy used by the AC released as heat.
Humans burning calories to stay alive creates heat, and thermodynamics that you spend energy to remove it or see the temperature rise. Whether that heat is hot air or bound as humidity shouldn't make a large difference.
You can see there that even at extremely dry conditions, if the operative (ambient + radiant) temperature is hot enough, it will cause heat discomfort. Even if the human starts sweating, that'll only reduce the temperature a bit so dehumidification isn't the only role of air conditions, sensible cooling is also a factor.
https://www.rehva.eu/knowledge-base/rehva-journal/chapter/ai...
See the pie chart on page two: eletricity consumption from cooling systems is 17% of global consumption. The IPCC expects this usage to rise as temperatures rise.
I would also like to challenge the notion that human beings understand how to use air conditioning units. In pretty much every building I visited or vehicle I boarded with air conditioning, if the unit was on, the windows were also wide open at the same time. In Greece, where I'm from, in the summer, you can cool down just by walking past stores, with their doors thrown wide to signal they're open for business and their air conditioning blasting cool air onto the street. It may be 42°C in the shade, but in front of our shop, it's 15°! Come on in and buy our stuff! But put on your coat first.
Contemplate for a second the futility of this behaviour: air conditioning pumps heat out of a room, into the environment; leaving the windows open allows the heat to circulate back into the room. The unit typically has a thermostat, also typically set at an unrealistically low value, that would cause the user to turn on the heating in winter. The unit goes to work and pushes the warm air out trying to reach its target temperature. The warm air cycles back in from outside and tries to raise the temperature. The unit keeps working, and working, and working, wasting energy all the time. Eventually, this contributes to warming, which causes more people to buy and misuse air conditioning.
We might know how to survive a heat wave, by our clever use of technology, but we don't know how to use technology to avoid more and more severe heat waves.
Edit: because obviousy I also go into shops to buy stuff and I've never seen an air door used. If air doors are used, they are very, very rare.
The point is emergency management here. And I'd bet anything that somewhere there's a workable plan drawn up for exactly this kind of occurrence.
[1] https://en.wikipedia.org/wiki/Retailing_in_India#The_Indian_...
Aside from ACs having a limit on cooling far below “everyone packed in a building”, if you’ve ever done business in India, I don’t see how one could assume there would be a plan drawn up for this grand of a scenario, much less many smaller scale scenarios.
There's vastly more to India than a few metro cities. A quick google search reveals that around 65+ % of Indian population lives in rural areas.
India is in for some very dark times if the climate situation gets worse. The positive lining in the cloud is that we have some measure of political stability for the next 5 years.
Heat waves spur increases in violent crime, limited in some degree by the fact that people stay in their own homes in really hot (but not uninhabitably so) heat waves.
Heat waves that go further to where the only survivable solution is pulling people out of their homes into large communal shelters (whether they otherwise serve as offices or shopping malls or whatever) is...going to be very ugly.
And that's even before considering whether the facilities or supporting infrastructure (plumbing, electrical systems, etc.) are adequate to support these places being used as shelters. Almost certainly they won't be until it's happened and failed a few times, and even after that the places that most need it will be the least able to finance the necessary upgrades.
Of course you can't start digging while dying of heat stroke and you can't crowd people into any places (people are great space heaters). With education about proper measures a few days should be survivable for rural populations. In cities you just need air conditioning, there's no other viable way to cool large amounts of people.
Granted I don't know the wet-bulb temp actually exceeded 35C
The most effective preventive measure, in my experience, is to drink (~200ml of) mineral-filled water once every half an hour. The body's heat regulation mechanism works best when provided with sufficient amount of water. The problem only begins to manifest once the body water levels aren't good enough to dispose of heat as well as maintain blood circulation in which case the body prefers to give up heat regulation over fluid circulation.
Under normal circumstances, we are used to drinking water only when we get thirsty. Under extreme heat, however, by the time thirst signal kicks in it could be too late. I learned this the hard way during long-distance cycling. Since then I've followed cyclists' mantra of eat-before-hungry and drink-before-thirsty.
Another thing to keep in mind is to drink mineralized water (such as Gatorade, juices, tender coconut water, etc.,). When you sweat you also lose a lot of minerals so replenishing just water isn't good enough.
Most of the heat wave death in India doesn't occur in an urban setting as people have access to water within walking distance. It is the farmers who are in the most danger as a) They are directly exposed to sun b) They are engaged in strenuous physical activity. By the time they realize the danger they are in it'd be too late and they lose consciousness with no one around them to help out in vast agricultural fields.
35°C is slightly cooler than body temperature, so it would work just a little bit as a heatsink, but another degree or two and even that becomes ineffective.
So a large body of water stays cool for a long time, and then stabilizes around the daily average temperature, not the high.
However the acceptable temperature range in water is also much smaller because under water we exchange heat quickly and don't have a way to cool below the temperature of the water. Water above ~38°C would be dangerous to stay submersed in. Not a problem for huge bodies of water, but important to keep in mind on the small scale.