Some Irony: Most Likely Early Sites for Fatal Wet Bulb Extreme Temperatures are in the Persian Gulf.
Last edited Sat May 14, 2022, 06:44 PM - Edit history (1)
The paper I'll discuss in this post is this one: Colin Raymond and Tom Matthews and Radley M. Horton ,The emergence of heat and humidity too severe for human tolerance, Science Advances,6,19,eaaw1838,2020,doi 10.1126/sciadv.aaw1838
A thermometer with a bulb wrapped with soaked paper over which air is passing is called a "wet bulb" thermometer. When the air is not saturated with water, such a thermometer will always measure a temperature that is lower than the ambient temperature measured by a dry bulb. It is a crude device for measuring humidity. When I was a high school student, a very long time ago, we attached thermometers to the end of a dowel using a pin, wrapped the bulb with a soaked cotton ball, and swung the thermometer around by swinging the dowel with a wrist motion. One can still do this if one wishes. A simple arrangement with a fan also works.
The extreme temperatures we have been seeing around the world, some exceeding by a large margin 40°C - recent temperatures in India and Pakistan have been higher than 46°C and have approached 49°C - are much higher than normal body temperatures; most in vitro tests designed to mimic physiologic conditions are at 37°C, which can be taken to be "normal" body temperatures.
Having a fever of 42°C (around 106-107°F) is generally fatal, causing general organ failure, and the reason we don't die when ambient temperatures reach those levels, as they do more and more frequently is that we sweat. The high heat of vaporization of water absorbs heat, lowering body temperatures. However the rate at which the body can cool using evaporation is a function of its humidity; the higher the humidity, the less efficient evaporation becomes, and at a high enough wet bulb temperature, generally taken to be 35°C, although fatalities are observed at lower wet bulb temperatures.
Science Advances is an open sourced journal provided to the public free of charge by the American Association for the Advancement of Science; anyone can access the paper cited at the outset. For convenience however, I will excerpt a discussion from the introduction about fatal levels of wet bulb temperatures.
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)...
Reference 3 is one I've cited a number of times in a number of places, and which I have in my files, this one:
Jean-Marie Robine, Siu Lan K. Cheung, Sophie Le Roy, Herman Van Oyen, Clare Griffiths, Jean-Pierre Michel, François Richard Herrmann, Death toll exceeded 70,000 in Europe during the summer of 2003, Comptes Rendus Biologies, Volume 331, Issue 2,
2008, Pages 171-178.
This paper receives a tiny fraction of the discussions of Fukushima, where roughly 20,000 people died from seawater and almost no one died from radiation exposure, not that we give a rat's ass about the victims of seawater.
Please note the use of the word "regularly" which I have taken the liberty of putting in bold. It is reported that the death toll in India from the extreme heat is 25, but this is almost certainly an extreme under count, given that the death of 70,000 people in Europe was tied to wet bulb temperatures of 28°C. As the authors note, it is the temperature gradient that matters physiologically, bodies do generate heat internally and that heat must be removed in addition to ambient heat.
Anyway, the paper is open sourced. It behooves me only to reproduce a graphic from it and it's caption, noting a problem with the Persian Gulf in particular, and Southeast Asia in General:
The graphic:
(A) Shading shows the amount of global warming (since preindustrial) until TW = 35°C is projected to become at least a 1-in-30-year event at each grid cell according to a nonstationary GEV model. In blank areas, more than 4°C of warming is necessary. Black dots indicate ERA-Interim grid cells with a maximum TW (1979–2017) in the hottest 0.1% of grid cells worldwide. (B) Total area with TW of at least 35°C, as a function of mean annual temperature change ⟨T⟩ from the preindustrial period. Red (green) vertical lines highlight the lowest ⟨T⟩ for which there are nonzero areas over land (sea)—the respective ToE. (C) Bootstrap estimates of the ToE. See text for details of this definition and calculation.
Again, the paper is open sourced.
Anyone can read about it if they wish.
It's probably not as interesting as reading about Fukushima, or about how solar energy, wind energy, and electric cars will save the world, although apparently they haven't saved the world, aren't saving the world and won't save the world. These dangerous fantasies are not very good at generated energy, but they do a spectacular job of generating complacency.
No matter.
The die is cast.
Fukushima.
We're all melting down, as we might discover if, and only if, we look in the mirror..
Enjoy the weekend.
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