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> Study results indicate that limiting global warming to 1.5 °C would prevent most of the tropics from reaching the wet-bulb temperature of the human physiological limit of 35 °C.

Limit was hit in 2023: https://www.washingtonpost.com/climate-environment/2024/02/0...



If that is true, why haven't we seen mass death from repeated 35℃ breaches?


> why haven't we seen mass death from repeated 35℃ breaches?

Because we haven't seen very many 35℃ wet bulb temperature breaches yet. The nominal air temperature is much higher than that all the time around the world, but it's only when there is very high humidity at that temp that humans start to overheat.

IIRC there have only been a few instances so far where the web bulb temp limit has been breached, e.g. some instances around the Persian Gulf, and maybe also in Mexico near the Gulf of California (not sure about the latter if it's even been breached yet, but I know it's at risk).

Edit: Wikipedia page has a list, https://en.wikipedia.org/wiki/Wet-bulb_temperature#Highest_r.... There have only been 10 recorded instances where wet bulb temp exceeded 35C.


The breach is in wet-bulb temperature, not dry-bulb temperature. When you hear weather reports cover the temperature, then it's going to be the dry-bulb temperature--the actual temperature of the air.

Wet-bulb temperature is the minimum temperature you can reach by evaporative cooling (i.e., sweating). When wet-bulb temperature gets too close to core body temperature, you are physically incapable of shedding heat if you are not in air-conditioning, and how close it needs to be depends on how good health you are in.

But we actually have seen deaths in previous heat waves, which largely didn't even breach 30C wet-bulb. The 2003 European heat wave caused about 70,000 people to die, for example.


Do you have data on the demographic breakdown? The papers i have seen have the overwhelmong majority of those deaths in the 80 plus demographic, which is not anywhere near equivalent to an 18 to 50 year old death when doing the cost benefit analysis on any of the mitigation or avoidance policies we could enact



We have, all over the world.

For example, at least 24500 people died from heat-related causes in Europe during heat waves of summer 2022.

And that's just one of many examples.


In 1911 41,000 people died of a heave wave in France.

Highest ambient temperature ever recorded was in Death Valley in 1913.

In 1540 Europe had an extreme drought and heatwave that lasted 11 months.

I can go on and on. The 2022 heatwave wasn’t any more unusual than any other heat wave throughout history.


Please don't confuse the heat in Death Valley with humid heat. Don't get me wrong, that Death Valley heat will kill you, but as long as you have water and shade you will survive.

I posted about it before:

https://news.ycombinator.com/item?id=37455817#37459864

> You have to factor in humidity. > Scottsdale airport currently (1:40PM) is 108F (42.222C) w/ 14% humidity, meaning a wet-bulb of 71.11F (21.72778C).

> London tomorrow at noon is 86F (30C) w/ 52% humidity, meaning a wet-bulb of 72.76F (22.6444C).

> London will actually feel nastier.


Also London has terrible aircon.


dear fact-impaired readers - global temperature records are carefully kept by a multitude of authoritative sources, and increasingly so..

the Year 2023 was the Hottest Year on Record to date globally.. each month of 2023 (edit maybe not jan-feb?) was also the hottest recorded globally. The hottest day cumulatively across the world was in 2023. The nine hottest years on record globally were the last nine years.

Please use librarianship and science skills for factual information. multiple references available for the search-impaired


> each month of 2023 was also the hottest recorded globally.

Actually, I think January and February failed to breach the record--the El Nino didn't set up until April.

(But several of the later months absolutely shattered records, as did the year as a whole. 2023 as a whole breached the 2C limit).


> 2022 heatwave wasn’t any more unusual than any other heat wave throughout history

You can't think of one pertinent home gadget that was invented between 1911 and now?


I assume that you're alluding to the air conditioner, which was invented in 1901? The first home installation was in 1914, but that wasn't the date of the invention.

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


Oh let's play this game with COVID: "Nothing original, we had the Spanish Flu in 1918..."


Both of you can be right you know, it isn't mutually exclusive....


We cared less about mass death in 1911, as exemplified by WW1.


> limiting global warming to 1.5 °C would prevent most of the tropics from reaching the wet-bulb temperature of the human physiological limit of 35 °C.

We've had one year at the level of warming that is not yet expected to yield mass death from wet bulb events.

Give it time. There's no reason to think that the current warming trend will slow, stop, or reverse itself in the near term.


Why is there “no reason?” This has happened repeatedly throughout history. Climate has always changed. The only difference now is that “preventing” climate change is a huge industry.


Of course climate has changed in the past, but over geological time scales. We're witnessing change in real time, over a period of decades. It's the rate of change in climate that is accelerating.


The reasons for this increase in temperature persist and new contributing reasons are starting to appear, that create vicious feedback loops.


"Maybe it'll just -waves hands- magically happen" is "no reason". Saying "climate has changed in the past and therefore there is reason to believe that it will change in this particular way, in the future" does not logically follow.

Climate has changed repeatedly throughout history. Every time a temperature increase has changed to a temperature decrease, this must be preceded by the rate of temperature increase decreasing.

We observe the rate of temperature increase, continuing to increase.

Thus there is reason to believe that it will get hotter for some time, before it again gets colder.


> The only difference now is that “preventing” climate change is a huge industry.

Eh, causing it is in fact a much, much bigger industry.


Seriously the people who say "there is money to be made by lying about climate change" and then pointing to the few millions of dollars available in public research into climate and NOT the trillions of dollars from multiple countries in selling energy in the form of carbon bonds are just goofy.

These are the kind of people that had to cheat off you to pass biology yet insist that "the immune system works like this"


The 1.5 degrees are the average heatup over the globe, it varies across the regions - in Europe we have a higher raise, but we are not near the unliveable conditions, though we have plenty of heat deaths already. And of course, there is air condition. So even if temperatures reach dangerous levels, few people will experience it in full force.


Air conditioning? Most of the areas most at risk for high wet bulb temperatures already rely heavily on air conditioning to be habitable.

We'd be in serious trouble if we had a power failure triggered by a heat wave, which IIRC was a near miss in the central US heat wave last summer.




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