Planet already seeing temperatures beyond human tolerance

[bronxiteforever]

Health24
25 MAY 2020
Planet already seeing temperatures beyond human tolerance
People can acclimatise to heat and humidity to a point, but there is a point where it's like sitting in a steam room, and we just can't cool ourselves through sweating.

Researchers have predicted that if climate change goes unabated, the planet will experience intolerable heat in the decades ahead. But a new study has found that in certain global hot spots, it's already happening.... Upper limit humans can stand. In numerous instances, the study found, local conditions have approached or hit a "wet bulb" temperature of 35 degrees Celsius. That's a measure of heat and humidity similar to what local weather reports call "heat index". The 35-degree C mark would translate into a heat index of 160 degrees Fahrenheit.

... The new findings are another sign that "we already have many people living way above the level of risk," said Dr Mona Sarfaty, head of the Program on Climate and Health at George Mason University in Fairfax, Virginia. "And even these very extreme heat conditions are being seen now," she said.

... While the Persian Gulf saw the most dangerous heat, extremes were also recorded in India, Bangladesh, Pakistan, northwestern Australia and parts of Mexico. In the United States, levels around 30 C were seen near the Gulf Coast, in east Texas, Louisiana, Mississippi, Alabama and the Florida Panhandle.

https://www.health24.com/Lifestyle/Environmental-health/Climate-and-temperature/planet-already-seeing-temperatures-beyond-human-tolerance-20200525-2

[Turbineguy]

1. Air Conditioning

cools air to about 13.3 deg C (wet bulb) to remove excess humidity and then heats the air up to 22 for a perfect relative humidity of 50%.

It's the range of relative humidity that is important. If the air in the room is dry, 22 deg C will feel cold. If the humidity is high, that same temperature will feel warm.

The body has to "learn" how to regulate temperature. When I went to the tropics it took about a year before I was comfortable.

Obviously a 2 degree margin between the body and the surrounding air is an insufficient margin for heat transfer.

[bronxiteforever]

2. I should have realized that hatrack had already

posted the study along with an additional article.

From the original study:

Humans’ bipedal locomotion, naked skin, and sweat glands are constituents of a sophisticated cooling system (1). Despite these thermoregulatory adaptations, extreme heat remains one of the most dangerous natural hazards (2), with tens of thousands of fatalities in the deadliest events so far this century (3, 4). The additive impacts of heat and humidity extend beyond direct health outcomes to include reduced individual performance across a range of activities, as well as large-scale economic impacts (5–7). Heat-humidity effects have prompted decades of study in military, athletic, and occupational contexts (8, 9). However, consideration of wet-bulb temperature (TW) from the perspectives of climatology and meteorology began more recently (10, 11).

While some heat-humidity impacts can be avoided through acclimation and behavioral adaptation (12), there exists an upper limit for survivability under sustained exposure, even with idealized conditions of perfect health, total inactivity, full shade, absence of clothing, and unlimited drinking water (9, 10). A normal internal human body temperature of 36.8° ± 0.5°C requires skin temperatures of around 35°C to maintain a gradient directing heat outward from the core (10, 13). Once the air (dry-bulb) temperature (T) rises above this threshold, metabolic heat can only be shed via sweat-based latent cooling, and at TW exceeding about 35°C, this cooling mechanism loses its effectiveness altogether. Because the ideal physiological and behavioral assumptions are almost never met, severe mortality and morbidity impacts typically occur at much lower values—for example, regions affected by the deadly 2003 European and 2010 Russian heat waves experienced TW values no greater than 28°C (fig. S1). In the literature to date, there have been no observational reports of TW exceeding 35°C and few reports exceeding 33°C (9, 11, 14, 15). The awareness of a physiological limit has prompted modeling studies to ask how soon it may be crossed. Results suggest that, under the business-as-usual RCP8.5 emissions scenario, TW could regularly exceed 35°C in parts of South Asia and the Middle East by the third quarter of the 21st century (14–16).

https://advances.sciencemag.org/content/6/19/eaaw1838

And then of course from an interview of the author

In many of the world's hottest spots, Raymond noted, people not only lack access to airconditioning but commonly work outdoors.

https://www.health24.com/Lifestyle/Environmental-health/Climate-and-temperature/planet-already-seeing-temperatures-beyond-human-tolerance-20200525-2

[JackintheGreen]

3. Body adaptation is part of it for sure

I’ve lived in South Asia for almost a decade now, but I am weathering the pandemic in Louisiana. Everybody here is complaining about the heat already, but I’ve been spending all day every day outside under the pergola. But the last two summers over there have been brutal, often reaching wetbulb temps over 30C, and dry bulb temps nearing 45 (110+ F).

[bronxiteforever]

4. Wow! I would not last long there.

[Chainfire]

5. I live in the Florida Panhandle

And I promise you, that even for a native, it gets brutal outside for about three months of the year.

[42bambi]

6. In 50 years or so there will be a boom on earth sheltered solar powered dome homes.

[bronxiteforever]

7. +1

[flotsam]

8. They are playing with celsius not centigrade

and discussing "real feel" temps of 150 degrees plus...

A centigrade scale has 100 degrees between the freezing and boiling points of water. The original Celsius scale actually had a boiling point of 0 degrees and freezing point of 100 degrees. It ran in the opposite direction of the modern scale