From the THE EARTH INSTITUTE AT COLUMBIA UNIVERSITY and “the edge of wetness” department.
Humidity may prove breaking point for some areas as temperatures rise, says study
From US south to China, heat stress could exceed human endurance
Climate scientists say that killer heat waves will become increasingly prevalent in many regions as climate warms. However, most projections leave out a major factor that could worsen things: humidity, which can greatly magnify the effects of heat alone. Now, a new global study projects that in coming decades the effects of high humidity in many areas will dramatically increase. At times, they may surpass humans’ ability to work or, in some cases, even survive. Health and economies would suffer, especially in regions where people work outside and have little access to air conditioning. Potentially affected regions include large swaths of the already muggy southeastern United States, the Amazon, western and central Africa, southern areas of the Mideast and Arabian peninsula, northern India and eastern China.
“The conditions we’re talking about basically never occur now–people in most places have never experienced them,” said lead author Ethan Coffel, a graduate student at Columbia University’s Lamont-Doherty Earth Observatory. “But they’re projected to occur close to the end of the century.” The study will appears this week in the journal Environmental Research Letters.
Warming climate is projected to make many now-dry areas dryer, in part by changing precipitation patterns. But by the same token, as global temperatures rise, the atmosphere can hold more water vapor. That means chronically humid areas located along coasts or otherwise hooked into humid-weather patterns may only get more so. And, as many people know, muggy heat is more oppressive than the “dry” kind. That is because humans and other mammals cool their bodies by sweating; sweat evaporates off the skin into the air, taking the excess heat with it. It works nicely in the desert. But when the air is already crowded with moisture–think muggiest days of summer in the city–evaporation off the skin slows down, and eventually becomes impossible. When this cooling process halts, one’s core body temperature rises beyond the narrow tolerable range. Absent air conditioning, organs strain and then start to fail. The results are lethargy, sickness and, in the worst conditions, death.
Using global climate models, the researchers in the new study mapped current and projected future “wet bulb” temperatures, which reflect the combined effects of heat and humidity. (The measurement is made by draping a water-saturated cloth over the bulb of a conventional thermometer; it does not correspond directly to air temperature alone.) The study found that by the 2070s, high wet-bulb readings that now occur maybe only once a year could prevail 100 to 250 days of the year in some parts of the tropics. In the southeast United States, wet-bulb temperatures now sometimes reach an already oppressive 29 or 30 degrees Celsius; by the 2070s or 2080s, such weather could occur 25 to 40 days each year, say the researchers.
Lab experiments have shown wet-bulb readings of 32 degrees Celsius are the threshold beyond which many people would have trouble carrying out normal activities outside. This level is rarely reached anywhere today. But the study projects that by the 2070s or 2080s the mark could be reached one or two days a year in the U.S. southeast, and three to five days in parts of South America, Africa, India and China. Worldwide, hundreds of millions of people would suffer. The hardest-hit area in terms of human impact, the researchers say, will probably be densely populated northeastern India.
“Lots of people would crumble well before you reach wet-bulb temperatures of 32 C, or anything close,” said coauthor Radley Horton, a climate scientist at Lamont-Doherty. “They’d run into terrible problems.” Horton said the results could be “transformative” for all areas of human endeavor–“economy, agriculture, military, recreation.”
The study projects that some parts of the southern Mideast and northern India may even sometimes hit 35 wet-bulb degrees Celsius by late century–equal to the human skin temperature, and the theoretical limit at which people will die within hours without artificial cooling. Using a related combined heat/humidity measure, the so-called heat index, this would be the equivalent of nearly 170 degrees Fahrenheit of “dry” heat. But the heat index, invented in the 1970s to measure the “real feel” of moist summer weather, actually ends at 136; anything above that is literally off the chart. On the bright side, the paper says that if nations can substantially cut greenhouse-gas emissions in the next few decades, the worst effects could be avoided.
Only a few weather events like those projected have ever been recorded. Most recent was in Iran’s Bandar Mahshahr, on July 31, 2015. The city of more than 100,000 sits along the Persian Gulf, where seawater can warm into the 90s Fahrenheit, and offshore winds blow moisture onto land. On that day, the “dry” air temperature alone was 115 degrees Fahrenheit; saturated with moisture, the air’s wet bulb reading neared the 35 C fatal limit, translating to a heat index of 165 Fahrenheit.
Bandar Mahshahr’s infrastructure is good and electricity cheap, so residents reported adapting by staying in air-conditioned buildings and vehicles, and showering after brief ventures outside. But this may not be an option in other vulnerable places, where many people don’t have middle-class luxuries.
“It’s not just about the heat, or the number of people. It’s about how many people are poor, how many are old, who has to go outside to work, who has air conditioning,” said study coauthor Alex deSherbinin of Columbia’s Center for International Earth Science Information Network. De Sherbinin said that even if the weather does not kill people outright or stop all activity, the necessity of working on farms or in other outdoor pursuits in such conditions can bring chronic kidney problems and other damaging health effects. “Obviously, the tropics will suffer the greatest,” he said. Questions of how human infrastructure or natural ecosystems might be affected are almost completely unexplored, he said.
Only a handful of previous studies have looked at the humidity issue in relation to climate change. It was in 2010 that a paper in the Proceedings of the National Academy of Sciences proposed the 35-degree survivability limit. In 2015, researchers published a paper in the journal Nature Climate Change that mapped areas in the southern Mideast and Persian Gulf regions as vulnerable to extreme conditions. There was another this year in the journal Science Advances, zeroing in on the densely populated, low-lying Ganges and Indus river basins. The new study builds on this earlier research, extending the projections globally using a variety of climate models and taking into account future population growth.
Elfatih Eltahir, a professor of hydrology and climate at the Massachusetts Institute of Technology who has studied the issue in the Mideast and Asia, said the new study “is an important paper which emphasizes the need to consider both temperature and humidity in defining heat stress.”
Climate scientist Steven Sherwood of the University of New South Wales, who proposed the 35-degree survivability limit, said he was skeptical that this threshold could be reached as soon as the researchers say. Regardless, he said, “the basic point stands.” Unless greenhouse emissions are cut, “we move toward a world where heat stress is a vastly greater problem than it has been in the rest of human history. The effects will fall hardest on hot and humid regions.”
###
The paper, “Temperature and humidity based projections of a rapid rise in global heat stress exposure during the 21st century,” is available online here and is open access.
Abstract
As a result of global increases in both temperature and specific humidity, heat stress is projected to intensify throughout the 21st century. Some of the regions most susceptible to dangerous heat and humidity combinations are also among the most densely populated. Consequently, there is the potential for widespread exposure to wet bulb temperatures that approach and in some cases exceed postulated theoretical limits of human tolerance by mid- to late-century. We project that by 2080 the relative frequency of present-day extreme wet bulb temperature events could rise by a factor of 100–250 (approximately double the frequency change projected for temperature alone) in the tropics and parts of the mid-latitudes, areas which are projected to contain approximately half the world’s population. In addition, population exposure to wet bulb temperatures that exceed recent deadly heat waves may increase by a factor of five to ten, with 150–750 million person-days of exposure to wet bulb temperatures above those seen in today’s most severe heat waves by 2070–2080. Under RCP 8.5, exposure to wet bulb temperatures above 35 °C—the theoretical limit for human tolerance—could exceed a million person-days per year by 2080. Limiting emissions to follow RCP 4.5 entirely eliminates exposure to that extreme threshold. Some of the most affected regions, especially Northeast India and coastal West Africa, currently have scarce cooling infrastructure, relatively low adaptive capacity, and rapidly growing populations. In the coming decades heat stress may prove to be one of the most widely experienced and directly dangerous aspects of climate change, posing a severe threat to human health, energy infrastructure, and outdoor activities ranging from agricultural production to military training.
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Meanwhile people continue to retire from Minnesota o Florida and from Victoria to Queensland despite the Wrmistas’ warnings. Some like it hot!
When conjecture and science collide. Conjectured predictions are the result of explaining history without regard to observed data. Or even because of it when it is inconvenient.
I lived in Abu Dhabi in the early 1970s. That’s on the Persian Gulf, but on our side we called it the Arabian Gulf. Humidity was very high – when you walk out the door, your shirt is stuck to you within a couple of steps. I remember a friend sticking a thermometer in the sea near the beach one day and it was 104F. Abu Dhabi was doing pretty well back then, with its building and infrastructure projects all getting underway, and people moving in from all over the world to work there. And a lot of the work was outside. Back then, it was a great place to be. So the projected future conditions that these people are desperately trying to scare you with aren’t exactly new or debilitating. And even if you believe that they are, just take a look at the map and note the vast land areas that won’t be experiencing those conditions.
BTW Steven Sherwood authored that egregious paper that coloured the non-hot-spot bright red.
We’re doomed. Again.
A further demonstration the “climate science” is the product of rich white people from Northern Europe. Homo Sapiens is a tropical species. We can survive the mid day heat by finding shady spots and resting until the cool of the evening. Many people who lived in hot climates before modern times adapted by taking a siesta during the oppressive hours and going back to work in the late afternoon.
I continue to insist that warmunism is the last socially acceptable form of racism.
Humidity cools the surface. Water vapor is buoyant. The molecular weight of water is 18. Air is around 29.
True enough, but water vapor isn’t exactly water monomers. Don’t overlook the strength of water’s hydrogen bonding, to itself and other chemicals. Plus, for gases, ‘buoyancy’ isn’t what people think it is. For the US standard atmosphere (which is dry), the typical velocity is on the order of 1 km/sec at standard temperature and pressure. Water monomers will move faster, water dimers wouldn’t (on the order of 1.4 km/sec for monomers, dimers would be a bit under 1 km/sec). Gases are completely miscible, unless physically constrained, and even then, they’ll mix fully within the constraints given sufficient time. Liquids, though, may or may not. Don’t conflate them because both are subject to bulk fluid flows.
“The conditions we’re talking about basically never occur – people have never experienced them… but that doesn’t mean that without super-big funding going forward they aren’t horribly real and terrifying and getting worse than we auggghhh!!!!!!”
No. It’s never been 32 C before. The fact that people all over America are rushing to places with 40C summer temperatures seems to be irrelevant. The fact that people love and operate in such temps with little negative effects and lower mortality than cooler places is irrelevant.
The fact is the study is wrong from every aspect it’s hardly worth even commenting. The temperate change they proclaim is 90% of the change they predicted. In other words we have gotten only 10% of the temperature change they predict. After 70 years only 10%. They expect in the next 70 the other 90%. This is normally called speculative because they have missed every prediction they made before.
Even if we give them their prediction there is no evidence that such temperatures will result in negative consequences. Every degree rise in the past RESULTS IN MORE LIFE. Healthier life and longer lives. But we are to believe among other things that we reached the perfect temperature and every change from here is bad. Normally this would be considered improbable. Oh well. This is climate sciology and normal rules don’t apply.
Another problem. Even if species were to die who is to say that this is unnatural. What is the natural extinction rate and formation rate? Large extinctions were associated with advancement of life. Increased rate of evolution is potentially very good. We dont know. We have no way of judging if it is Good or bad. Nothing will probably happen but if it does we still can’t say it is bad.
In the meantime Man continues to improve our handling of natural disasters to the point that almost nobody dies anymore from any negative thing in the environment.
No regional skill, but let’s ignore that and make regional claims.
Excellent point.
Did I misunderstand something about the “wet-bulb” measurement? Because if they are talking about really humid days in the upper 90s (Fahrenheit) THAT HAPPENS ALL SUMMER IN THE DEEP SOUTH.
Not necessarily. In fact, the HHH here is rarely upper 90s with afternoon humidity in the upper 90s. ‘Average summer highs are 90F (25C = 77F, 30C = 86F, 35C = 95F), with a 1sd of 4F or so. I might see no 98F days at all during the 94 days of summer or I might see 30 of them. I can’t recall the last 100F day here, it has been that long. Afternoon relative humidity rarely gets above 50%. Every night, though, it’ll hit 100%, with condensation occurring, sometimes accompanied by fog. Every morning that condensation evaporates.
People need to remember that not everyone lives in the city. AGW is a city thing related to how swarms alter the local environment. Bee hives and ant mounds do the same thing. Forests, too.
It’s been almost a week since I read such utter garbage.
Using global climate models is a total waste of time.
More end of the Earth fantasies from climate ‘scientists’
Surely increased humidity also creates clouds that cool during the day and warms the nights if you look at USA max/min temp data as well as precipitation since 1900. The 1930’s were dry and it turned into a dust bowl. Now there is more rain and specific humidity that has lowered days over 100deg F to one 3rd the level in the 1930’s according to the EPA graph and helped reduce forest fires by 80% since the 1930’s according the the US Forest service, except in the brain of CA Gov Jerry Brown. Warming now is not your grandfathers global warming since it is mostly at nightime with more cloud clover and the heat island effect that helps agriculture locally. We need more temperature data that is split between night and day to do relevant climate science. Hard to find. Some of this is unfortunately reversing with a cooling Pacific and lower solar activity that is cooling the planet rapidly since the El Nino turned into a cool La Nina to join the cool PDO cycle change about 2007.
I live in Western Canada. That was some scary stuff until I realized they weren’t saying worse than MINUS 32. So, uh, never mind, eh!
I have about a foot of humidity on my driveway. I told it it’s supposed to be up in the atmosphere but it’s not moving.
Complete and utter drivel, considering climate models can’t even produce a single cloud and convectional thunderstorm.
Not only do these people simply write down whatever their fevered imagination produces, they are also very repetitive. Can any of them even conjure up a disaster scenario that we haven’t heard before, many times? Somebody needs to tell them just how boring they are.
I published a series of articles, in Indian Journal of Meteorology, Hydrology & Geophysics, related to human comfort related issues. They are as follows:
1. Effect of radiation on human comfort – 25:433-440 (1974)
It presents a discomfort index for seasons over India using global solar radiation and net radiation. Also compared the radiation discomfort index with temperature discomfort index, wet bulb temperature and humidity mixing ratio;
2. Effective pollution potential over ten Indian stations – 25:445-448 (1974)
Presents the vertical temperature change versus effective pollution potential index
3. Simple formulae for the estimation of wet bulb temperature and precipitable water – 27:163-166 (1976)
Presented methods to estimate wet bulb temperature and precipitable water in the total vertical column
4. Wet bulb temperature distribution over India – 27:167-171 (1976)
Present the spatial and temporal distribution of wet bulb temperature over India and also discussed the effective temperature diagrams over selected cities. Effective temperature — related to wet &dry bulb temperatures and wind speed.
5. A method of forecasting the weather associated with western disturbances – 29:515-520 (1978)
It presents a schematic presentation of circulation patterns in summer and winter and their associated heat and cold waves over India;
3 rd para of the above article “warming climate — death” — a highly hypothetical.
Dr. S. Jeevananda Reddy
Thank you Dr. Very interesting.
They appear to have omitted rain from their model.
Their example of Bandar Mahshahr is a location currently beyond the monsoonal zone, where a sufficient
column of humidity never builds to produce convective monsoonal rain. In simple terms, it isn’t humid long enough to rain. Large areas of the world are in a similar position.
Of course, were it more humid for longer, it would rain and cool substantially.
This is nothing more than more Munchausen syndrome behavior from climate science frauds
Around here, “But it’s a dry cold” is more likely to be said.
I would like to see some kind of calculation to justify where the heat is going to come from to bring the wet bulb temperature above 32°C. The heat required is definitely not linear with temperature.
For my entire life I have lived, went to school and worked in the SE USA. Until I went to college I never went to a school with air conditioning. No house I lived in or visited had air conditioning again until I left for college. Two-thirds of my career I worked outside from Spring through Fall in temperatures over 90 F(32 C) and mega humidity from sunrise to sunset. Sure it was hot but it didn’t stop us from working or playing outside and no one we lived or worked with died of heat stroke. I did recommend in a legislative subcommittee meeting one time that we could significantly reduce energy use in our state and cut school budgets by requiring public schools and universities to turn off their air conditioning. Public school and university electric bills are a significant portion of the education budget. Some old timers at the meeting agreed. Like myself they had not grown up with air conditioning,
“Humidity may prove breaking point for some areas as temperatures rise, says study”
Only scientific evidence points to satellites observing a decline in humidity over decades. Therefore the fact is that temperatures have only slightly increased while humidity has declined.
A decline in humidity, but a increase in temperature doesn’t imply there has been an increase in energy at all. For there to be an increase heat detected both humidity and temperature increases need to be observed.
Global temperatures warming slightly mean very little while humidity is declining because the lower the water vapor, the less energy is needed to reach the same temperature as before.
Global warming may well just be a change in humidity and nothing to do with an actual change in temperature (energy).
“Only scientific evidence points to satellites observing a decline in humidity over decades. Therefore the fact is that temperatures have only slightly increased while humidity has declined.”
No it doesn’t …..
http://onlinelibrary.wiley.com/doi/10.1029/2010JD014192/pdf
“We conclude from this that it is doubtful that these
negative long‐term specific humidity trends in the NCEP/NCAR reanalysis are realistic for several reasons. First, the newer reanalyses include improvements specifically designed to increase the fidelity of long‐term trends in their parameters, so the positive trends found there should be more reliable than in the older reanalyses. Second, all of the reanalyses except the NCEP/NCAR assimilate satellite radiances rather than being
solely dependent on radiosonde humidity measurements to constrain upper tropospheric humidity. Third, the NCEP/NCAR reanalysis exhibits a large bias in tropical upper tropospheric specific humidity. And finally, we point out that there exists no
theoretical support for having a positive short‐term water vapor feedback and a negative long‐term one.”
That paper refers to because ENSO shows positive trends then long term should also have positive trends. Not true because ENSO only affects the atmosphere with each trend for a limited time. The long term trend involves many years without any ENSO trend and this likely would be the most important factor. The increase in El Nino’s are reasonable for this positive short term trend and are irrelevant to the long term trend when ENSO doesn’t have one.
There is support for having a positive short term water vapour feedback and long negative trend because changing trends in ENSO are only temporary and occur less than they don’t. The background trend is dominating the ENSO one due to declining cloud albedo and increasing sunshine hours.
I survived living in New Orleans without AC during the summerz many years ago. School in September was a treat. Sweat would drip from your face and make the ink on your paper run.
The thing I’ve noticed with the way climate science is reported is that it seems some people were never taught how to screen papers. Studies are always just “That’s interesting but so what” because by their nature they haven’t managed to produce anything tangible. Experimental papers are the best. You can have 100 studies and models and it looks like a lot of “evidence” but all it is, is noise.
When I did my PhD the big gold rush was for interdigital electrodes on capacitors, with exotic materials, leading to massive magnetoresistance or ferroelectric effect or whatever. And when you took the time to read the paper and see the tests you realised it was because the devices were lossy as hell. It wasn’t a real effect. And that’s even with experimental results. The hard road to repeatable results were a thin one as well.
You need to learn to screen out the garbage. And stop believing in this peer review myth. Or in the low uncertainty for data sets.
That said when every hypothetical idea is presented as fact by the media and believed by politicians then I can see why you need to keep up with the madness.
Baloney. Their premises are all wrong. I served in Fort Polk during the early 90s. We considered a day with a wet-bulb temperature 90F (32C) a normal summer day. In those conditions, we routinely:
– put on heavy clothing including helmets and bulletproof vests
– sealed ourselves in poorly ventilated metal boxes (self-propelled howitzers, etc)
– engaged in heavy manual labor.
Local farmers did much the same in their tractors and other farm machinery.
Yes, there are some things you need to do to mitigate the effects. The first is to acclimate to the climate. You can’t get off the plane from Minnesota and expect to keep up with that level of activity. But when you live down there? Acclimation happens. Second and probably more important is to stay hydrated. Even at 100% humidity, your body needs fluids. 1-2 quarts an hour depending on your level of activity. 5 gallons per person per day was considered normal. Northerners can’t imagine being able to take in that much fluid a day. And frankly, I couldn’t either when I was first stationed there. It becomes normal.
The bottom line is that even assuming their worst case scenario, it’s no worse than humans regularly face and thrive in today. Their “death threshold” is pure bunk.