Extreme Temperature Diary- Sunday November 5th, 2023/Main Topic: Another Study Warning That Climate Driven Heat May Make Some Parts of Our World Uninhabitable

The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Another Study Warning That Climate Driven Heat May Make Some Parts of Our World Uninhabitable

Dear Diary. Last month yet another study was published which indicated that some parts of our world will become uninhabitable simply because of extreme heat. It would appear that we are well on our way towards that unfortunate destination looking at Maximilliano Herrera’s record reports, which I post everyday below my main topic of each of my blogs. I ask myself why am I driven so much to warn people about the consequences of not reigning in carbon pollution through this blog, to write World of Thermo kid’s climate books, and to compile of record statistics? Because I don’t want to see my fellow human beings suffer from intolerable lives. After all, life as of 2023 is challenging enough as it is.

Imagine what it could be like fifty years from now in 2073 if Dr. James Hansen’s latest forecast scenario came to fruition in a +3.5°C above preindustrial conditions world, in which billions are starving and migrating. This is why one of my compatriots, Maximiliano Herrera (Extreme Temperatures Across the World on Twitter or now X), is so driven to report records and compile climate stats. Both of us want to warn our fellow human beings of a too hot to live environment. Both of us won’t live until the year 2073, but we would like people who do to inherit a livable planet similar to what we have in 2023, if not better.

Here are details on that study from Desdemona Despair:

Climate-driven extreme heat may make parts of Earth too hot for humans – “If temperatures continue to rise, we will live in a world where crops are failing and millions or billions of people are trying to migrate because their native regions are uninhabitable” – Desdemona Despair

Climate-driven extreme heat may make parts of Earth too hot for humans – “If temperatures continue to rise, we will live in a world where crops are failing and millions or billions of people are trying to migrate because their native regions are uninhabitable.”

Annual hot-hours under (A) 1.5, (B) 2, (C) 3, and (D) 4 °C of warming relative to preindustrial level, (E) population projection in 2050 following the Shared Socioeconomic Pathway 2, and (F) population subject to accumulated duration of 1 wk to 3 mo of uncompensable heat stress annually under 1–4 °C of global warming (the shaded area corresponds to the 10th to 90th percentiles of CMIP6 model spread). Rectangles in panel a delineate regions where heat exposure increases with global warming are particularly large and will be examined in detail in later sections. Graphic: Vecellio, et al., 2023 / PNAS

By Aaron Wagner
9 October 2023

UNIVERSITY PARK, Pa. (PennState) – If global temperatures increase by 1 degree Celsius (C) or more than current levels, each year billions of people will be exposed to heat and humidity so extreme they will be unable to naturally cool themselves, according to interdisciplinary research from the Penn State College of Health and Human Development, Purdue University College of Sciences and Purdue Institute for a Sustainable Future.

Results from a new article published today (Oct. 9) in Proceedings of the National Academy of Sciences indicated that warming of the planet beyond 1.5 C above preindustrial levels will be increasingly devastating for human health across the planet.  

Humans can only withstand certain combinations of heat and humidity before their bodies begin to experience heat-related health problems, such as heat stroke or heart attack. As climate change pushes temperatures higher around the world, billions of people could be pushed beyond these limits.

Since the start of the industrial revolution, when humans began to burn fossil fuels in machines and factories, temperatures around the world have increased by about 1 C, or 1.8 degrees Fahrenheit (F). In 2015, 196 nations signed the Paris Agreement which aims to limit worldwide temperature increases to 1.5 C above pre-industrial levels.

The research team modeled global temperature increases ranging between the Paris Agreement target of 1.5 C and a worst-case-scenario level of 4 C to identify areas of the planet where warming would lead to heat and humidity levels that exceed human limits.

“To understand how complex, real-world problems like climate change will affect human health, you need expertise both about the planet and the human body,” said co-author W. Larry Kenney, professor of physiology and kinesiology, the Marie Underhill Noll Chair in Human Performance at Penn State and co-author of the new study. “I am not a climate scientist, and my collaborators are not physiologists. Collaboration is the only way to understand the complex ways that the environment will affect people’s lives and begin to develop solutions to the problems that we all must face together.”

Map showing annual hot-hours over South Asia (A–D), East Asia (E–H), North Africa (I–L), Middle East (M–P), and North America (Q–T) under 1.5, 2, 3, and 4 °C of warming relative to preindustrial level. Graphic: Vecellio, et al., 2023 / PNAS

A threat to billions 

The ambient wet-bulb temperature limit for young, healthy people is about 31 C, which is equal to 87.8 F at 100% humidity. However, in addition to temperature and humidity, the threshold for any individual at a specific moment also depends on their exertion level and environmental factors, including wind speed and solar radiation. In human history, temperatures and humidity that exceed human limits have been recorded only a limited number of times — and only for a few hours at a time — in the Middle East and Southeast Asia, according to the researchers.

Results of the study indicate that if global temperatures increase by 2 C above pre-industrial levels, the 2.2 billion residents of Pakistan and India’s Indus River Valley, the one billion people living in eastern China and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat surpassing human tolerance.

These regions would primarily experience high-humidity heatwaves, which can be more dangerous because the air cannot absorb excess moisture. This limits evaporation of sweat from human bodies and moisture from some infrastructure, like evaporative coolers. Troublingly, researchers said, these regions are also in lower-to-middle income nations, so many of the affected people may not have access to air conditioning or any effective way to mitigate the negative health effects of the heat.

If warming of the planet continues to 3 C above pre-industrial levels, the researchers concluded, heat and humidity levels that surpass human tolerance would begin to affect the Eastern Seaboard and the middle of the United States — from Florida to New York and from Houston to Chicago. South America and Australia would also experience extreme heat at that level of warming.

At current levels of heating, the researchers said, the United States will experience more heatwaves, but these heatwaves are not predicted to surpass human limits as often as in other regions of the world. Still, the researchers cautioned that these types of models often do not account for the worst, most unusual weather events.

“Models like these are good at predicting trends, but they do not predict specific events like the 2021 heatwave in Oregon that killed more than 700 people or London reaching 40 C last summer,” said lead author Daniel Vecellio, a bioclimatologist who completed a postdoctoral fellowship at Penn State with Kenney. “And remember, heat levels then were all below the limits of human tolerance that we identified. So, even though the United States will escape some of the worst direct effects of this warming, we will see deadly and unbearable heat more often. And — if temperatures continue to rise — we will live in a world where crops are failing and millions or billions of people are trying to migrate because their native regions are uninhabitable.”

(A) Global and (B-F) regional annual person-hours subject to uncompensable heat stress under 1–4 °C warming relative to preindustrial levels. Total person-hours (black) are decomposed into two parts with dry bulb temperature less (humid; blue) or greater (nonhumid; red) than 40 °C. The shaded area around black curves represents the 10th to 90th percentiles of CMIP6 model spread. The regions are defined as rectangles in Fig. 1A. Graphic: Vecellio, et al., 2023 / PNAS

Understanding human limits and future warming 

Over the last several years, Kenney and his collaborators have conducted 462 separate experiments to document the combined levels of heat, humidity and physical exertion that humans can tolerate before their bodies can no longer maintain a stable core temperature.

“As people get warmer, they sweat, and more blood is pumped to their skin so that they can maintain their core temperatures by losing heat to the environment,” Kenney said. “At certain levels of heat and humidity, these adjustments are no longer sufficient, and body core temperature begins to rise. This is not an immediate threat, but it does require some form of relief. If people do not find a way to cool down within hours, it can lead to heat exhaustion, heat stroke and strain on the cardiovascular system that can lead to heart attacks in vulnerable people.”

In 2022, Kenney, Vecellio and their collaborators demonstrated that the limits of heat and humidity people can withstand are lower than were previously theorized.

“The data collected by Kenney’s team at Penn State provided much needed empirical evidence about the human body’s ability to tolerate heat,” said co-author Matthew Huber, professor of Earth, atmospheric and planetary sciences at Purdue University. “Those studies were the foundation of these new predictions about where climate change will create conditions that humans cannot tolerate for long.”

“Humid heat is going to be a much bigger threat than dry heat. Governments and policymakers need to re-evaluate the effectiveness of heat-mitigation strategies to invest in programs that will address the greatest dangers people will face. Qinqin Kong, graduate student of Earth, atmospheric and planetary sciences at Purdue University

When this work was published, Huber, who had already begun work on mapping the impacts of climate change, contacted Vecellio about a potential collaboration. Huber had previously published widely cited work proposing a theoretical limit of humans’ heat and humidity limits.

The researchers, along with Huber’s graduate student, Qinqin Kong, decided to explore how people would be affected in different regions of the world if the planet warmed by between 1.5 C and 4 C. The researchers said that 3 C is the best estimate of how much the planet will warm by 2100 if no action is taken.

“Around the world, official strategies for adapting to the weather focus on temperature only,” Kong said. “But this research shows that humid heat is going to be a much bigger threat than dry heat. Governments and policymakers need to re-evaluate the effectiveness of heat-mitigation strategies to invest in programs that will address the greatest dangers people will face.”

Staying safe in the heat 

Regardless of how much the planet warms, the researchers said that people should always be concerned about extreme heat and humidity — even when they remain below the identified human limits. In preliminary studies of older populations, Kenney found that older adults experience heat stress and the associated health consequences at lower heat and humidity levels than young people.

“Heat is already the weather phenomenon that kills the most people in the United States,” Vecellio, now a postdoctoral researcher at George Mason University’s Virginia Climate Center, said. “People should care for themselves and their neighbors — especially the elderly and sick — when heatwaves hit.”

The data used in this study examined the body’s core temperatures, but the researchers said that during heatwaves, people experience health problems from other causes as well. For example, Kenney said that most of the 739 people who died during Chicago’s 1995 heatwave were over 65 and experienced a combination of high body temperature and cardiovascular problems, leading to heart attacks and other cardiovascular causes of death.

“If people do not find a way to cool down within hours, it can lead to heat exhaustion, heat stroke and strain on the cardiovascular system that can lead to heart attacks in vulnerable people. W. Larry Kenney, professor of physiology and kinesiology and the Marie Underhill Noll Chair in Human Performance at Penn State

Looking to the future 

To stop temperatures from increasing, the researchers cite decades of research indicating that humans must reduce the emission of greenhouse gases, especially the carbon dioxide emitted by burning fossil fuels. If changes are not made, middle-income and low-income countries will suffer the most, Vecellio said.

As one example, the researchers pointed to Al Hudaydah, Yemen, a port city of more than 700,000 people on the Red Sea. Results of the study indicated that if the planet warms by 4 C, this city can expect more than 300 days when temperatures exceed the limits of human tolerance every year, making it almost uninhabitable.

“The worst heat stress will occur in regions that are not wealthy and that are expected to experience rapid population growth in the coming decades,” Huber said. “This is true despite the fact that these nations generate far fewer greenhouse gas emissions than wealthy nations. As a result, billions of poor people will suffer, and many could die. But wealthy nations will suffer from this heat as well, and in this interconnected world, everyone can expect to be negatively affected in some way.”

The National Institute on Aging, the National Aeronautics and Space Administration and the National Science Foundation supported this research.

Climate-driven extreme heat may make parts of Earth too hot for humans

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Greatly enhanced risk to humans as a consequence of empirically determined lower moist heat stress tolerance

ABSTRACT: As heatwaves become more frequent, intense, and longer-lasting due to climate change, the question of breaching thermal limits becomes pressing. A wet-bulb temperature (Tw) of 35 °C has been proposed as a theoretical upper limit on human abilities to biologically thermoregulate. But, recent—empirical—research using human subjects found a significantly lower maximum Tw at which thermoregulation is possible even with minimal metabolic activity. Projecting future exposure to this empirical critical environmental limit has not been done. Here, using this more accurate threshold and the latest coupled climate model results, we quantify exposure to dangerous, potentially lethal heat for future climates at various global warming levels. We find that humanity is more vulnerable to moist heat stress than previously proposed because of these lower thermal limits. Still, limiting warming to under 2 °C nearly eliminates exposure and risk of widespread uncompensable moist heatwaves as a sharp rise in exposure occurs at 3 °C of warming. Parts of the Middle East and the Indus River Valley experience brief exceedances with only 1.5 °C warming. More widespread, but brief, dangerous heat stress occurs in a +2 °C climate, including in eastern China and sub-Saharan Africa, while the US Midwest emerges as a moist heat stress hotspot in a +3 °C climate. In the future, moist heat extremes will lie outside the bounds of past human experience and beyond current heat mitigation strategies for billions of people. While some physiological adaptation from the thresholds described here is possible, additional behavioral, cultural, and technical adaptation will be required to maintain healthy lifestyles.

SIGNIFICANCE: Increased heat and humidity potentially threaten people and societies. Here, we incorporate our laboratory-measured, physiologically based wet-bulb temperature thresholds across a range of air temperatures and relative humidities, to project future heat stress risk from bias-corrected climate model output. These vulnerability thresholds substantially increase the calculated risk of widespread potentially dangerous, uncompensable humid heat stress. Some of the most populated regions, typically lower-middle income countries in the moist tropics and subtropics, violate this threshold well before 3 °C of warming. Further global warming increases the extent of threshold crossing into drier regions, e.g., in North America and the Middle East. These differentiated patterns imply vastly different heat adaption strategies. Limiting warming to under 2 °C nearly eliminates this risk.

Greatly enhanced risk to humans as a consequence of empirically determined lower moist heat stress tolerance

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:

Here is some more new October 2023 climatology:

Here is More Climate and Weather News from Sunday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Today’s News on Sustainable, Traditional Polluting Energy from Fossil Fuel, and the Green Revolution:

More from the Weather Department:

More on the Environment and Nature:

More on Other Science and the Beauty of Earth and this Universe:

If you like these posts and my work on record temperature ratios, please contribute via my PayPal widget on this site. Thanks in advance for any support. 

Guy Walton… “The Climate Guy”

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