Johnny Carson of the Tonight Show used to do a schtick called “The Edge of Wetness” which was a parody of a soap opera called “The Edge of Night”
It was he first thing that went through my mind after reading this press release citing a new worry about wet bulb temperature. Apparently it’s not just the heat, but the humidity too.
Researchers find future temperatures could exceed livable limits
This map shows the maximum wet-bulb temperatures reached in a climate model from a high carbon dioxide emissions future climate scenario with a global-mean temperature 12 degrees Celsius (21 degrees Fahrenheit) warmer than 2007. The white land areas exceed the wet-bulb limit at which researchers calculated humans would experience a potentially lethal level of heat stress. (Purdue University graphic/Matthew Huber)
WEST LAFAYETTE, Ind. – Reasonable worst-case scenarios for global warming could lead to deadly temperatures for humans in coming centuries, according to research findings from Purdue University and the University of New South Wales, Australia.
Researchers for the first time have calculated the highest tolerable “wet-bulb” temperature and found that this temperature could be exceeded for the first time in human history in future climate scenarios if greenhouse gas emissions continue at their current rate.
Wet-bulb temperature is equivalent to what is felt when wet skin is exposed to moving air. It includes temperature and atmospheric humidity and is measured by covering a standard thermometer bulb with a wetted cloth and fully ventilating it.
The researchers calculated that humans and most mammals, which have internal body temperatures near 98.6 degrees Fahrenheit, will experience a potentially lethal level of heat stress at wet-bulb temperature above 95 degrees sustained for six hours or more, said Matthew Huber, the Purdue professor of earth and atmospheric sciences who co-authored the paper that will be published in Thursday’s (May 6) issue of the Proceedings of the National Academy of Sciences.
“Although areas of the world regularly see temperatures above 100 degrees, really high wet-bulb temperatures are rare,” Huber said. “This is because the hottest areas normally have low humidity, like the ‘dry heat’ referred to in Arizona. When it is dry, we are able to cool our bodies through perspiration and can remain fairly comfortable. The highest wet-bulb temperatures ever recorded were in places like Saudi Arabia near the coast where winds occasionally bring extremely hot, humid ocean air over hot land leading to unbearably stifling conditions, which fortunately are short-lived today.”
The study did not provide new evaluations of the likelihood of future climate scenarios, but explored the impacts of warming. The challenges presented by the future climate scenarios are daunting in their scale and severity, he said.
“Whole countries would intermittently be subject to severe heat stress requiring large-scale adaptation efforts,” Huber said. “One can imagine that such efforts, for example the wider adoption of air conditioning, would cause the power requirements to soar, and the affordability of such approaches is in question for much of the Third World that would bear the brunt of these impacts. In addition, the livestock on which we rely would still be exposed, and it would make any form of outside work hazardous.”
While the Intergovernmental Panel on Climate Change central estimates of business-as-usual warming by 2100 are seven degrees Fahrenheit, eventual warming of 25 degrees is feasible, he said.
“We found that a warming of 12 degrees Fahrenheit would cause some areas of the world to surpass the wet-bulb temperature limit, and a 21-degree warming would put half of the world’s population in an uninhabitable environment,” Huber said. “When it comes to evaluating the risk of carbon emissions, such worst-case scenarios need to be taken into account. It’s the difference between a game of roulette and playing Russian roulette with a pistol. Sometimes the stakes are too high, even if there is only a small chance of losing.”
Steven Sherwood, the professor at the Climate Change Research Centre at the University of New South Wales, Australia, who is the paper’s lead author, said prolonged wet-bulb temperatures above 95 degrees would be intolerable after a matter of hours.
“The wet-bulb limit is basically the point at which one would overheat even if they were naked in the shade, soaking wet and standing in front of a large fan,” Sherwood said. “Although we are very unlikely to reach such temperatures this century, they could happen in the next.”
Humans at rest generate about 100 watts of energy from metabolic activity. Wet-bulb temperature estimates provide upper limits on the ability of people to cool themselves by sweating and otherwise dissipating this heat, he said. In order for the heat dissipation process to work, the surrounding air must be cooler than the skin, which must be cooler than the core body temperature. The cooler skin is then able to absorb excess heat from the core and release it into the environment. If the wet-bulb temperature is warmer than the temperature of the skin, metabolic heat cannot be released and potentially dangerous overheating can ensue depending on the magnitude and duration of the heat stress.
The National Science Foundation-funded research investigated the long-term implications of sustained greenhouse gas emissions on climate extremes. The team used climate models to compare the peak wet-bulb temperatures to the global temperatures for various climate simulations and found that the peak wet-bulb temperature rises approximately 1 degree Centigrade for every degree Centigrade increase in tropical mean temperature.
Huber did the climate modeling on supercomputers operated by Information Technology at Purdue (ITaP), Purdue’s central information technology organization. Sherwood performed the wet-bulb calculations.
“These temperatures haven’t been seen during the existence of hominids, but they did occur about 50 million years ago, and it is a legitimate possibility that the Earth could see such temperatures again,” Huber said. “If we consider these worst-case scenarios early enough, perhaps we can do something to address the risk through mitigation or new technological advancements that will allow us to adapt.”
Writers: Elizabeth K. Gardner, 765-494-2081, ekgardner@purdue.edu
Greg Kline, 765-494-8167, gkline@purdue.edu
Sources: Matthew Huber, 765-494-9531, huberm@purdue.edu
Steven Sherwood, +61 (2) 9385 8960, s.sherwood@unsw.edu.au
Related Web site:
Matthew Huber’s Climate Dynamics Prediction Laboratory
ABSTRACT
An Adaptability Limit to Climate Change Due to Heat Stress
Steven C. Sherwood, Matthew Huber
Despite the uncertainty in future climate change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature Tw, is surprisingly similar across diverse climates today. Tw never exceeds 31C. Any exceedence of 35C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7C, calling the habitability of some regions into question. With 11-12C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record.
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P.F. says:
“And what did they mean by “for the first time in human history.” When, in their minds, did human history begin”
Maybe just over 4,000 years ago, just after the Adam.
Australia’s AGW megaphone, the ABC (Alarmist Bull Crap), will fast track this story for sure. Catalyst, one of the ABC’s junk climate science friendly programs, may be the one to run it.
http://www.abc.net.au/catalyst/stories/2886106.htm
“The highest wet-bulb temperatures ever recorded were in places like Saudi Arabia near the coast where winds occasionally bring extremely hot, humid ocean air over hot land leading to unbearably stifling conditions, which fortunately are short-lived today.””
Does anyone know what the number of deaths were on these “short-lived” “wet-bulb” days? If “short-lived” is say 2 hours then wouldn’t people have dropped like flies? Just askin.’
Here in southern Minnesota we not only have the privilege of enjoying stretches of winter weather of -20 to-30F, but it’s balanced out by July and August days of 90 to 100F with 80-90% RH, although in recent years the range seems to have narrowed. Having busted my hump through quite a number of those 90 90 days, I can attest they are nothing you would wish for, and they are certainly at least potentially deadly. But having visited Florida in summer, a large strategic error in planning, I think the essential point of this study is utter hogwash.
They claim wet bulb temperatures never exceed 31C. By my reconning that’s 100F @88% RH, hard to imagine that doesn’t get surpassed fairly regularly already.
Here’s a fascinating site on the weather & temperature and effects on human physiology – with an emphasis on sports:
http://www.zunis.org/how_hot_is_hot_how_safe_is_safe.htm
Be sure to hit ‘next page’ at the bottom of each page to reach some interesting data, including info about the effects of UHI on sports.
Its vodoo science, and its been allowed into PNAS, that is the most amazing fact!
We were too hasty in criticising Pachauri, he was correct, there is a lot of vodoo science about.
It’s a stupid fallacy to think that we’be using fossil fuels for that long regardless of the arguments and activists. We’ve been on the road to decarbonisation since the dawn of history, going from burning hay (more cabron atoms) to the nuclear power.
In a century or so, as long as government gets out of the way and consumers demand more energy, we’ll either have fusion power or corporations will have massive heat recievers orbiting close to the sun which will transmit power across space from one transmitter to another until they reach Earth.
And there’s so much more to discover – we might even be stealing energy away from parallel dimensions where energy is exists but is of no use to anyone there because they are devoid of lifeforms.
Iwas on an Shell oiltanker in kuwait in the early 1950’s. This was the time of of an uprising in Iran which closed Iranian oil fields and ports. BP , who at that time had a monopoly on Iranian oil shipping, could not get their tankers into Abadan and they were all anchored off the coast of Kuwait. They had, when we arrived, been there several weeks. The point of this story is, that during all that time and whilst we were there for several days, the temperature was over 100F and the humidity was also extremely high so that the whole area was in a thick mist 24hrs a day. Although there were reports of several cases of heat exhaustion, our pumpman was one of them, there were no deaths reported. The only precautionary treatment prescribed that I remember was an increased dosage of salt tablets per day. Perhaps someone out there has some records of this Gulf phenomena of high temperatures combined with very high humidity. I also think that these conditions also currently exist in tropical rainforests around the world in which indigenous peoples survive quite happily so why the scaremongering?
Fahrenheit? Who uses Fahrenheit?
If this research does show anything, it must be the following:
1. Using models you can get any situation you could dream of. The same model can be used to show that CO2 would fall down as snow, like it happens on Mars in winter.
2. This kind of crap is now even accepted for publication in PNAS. It is the most striking evidence of how corrupt the peer-review process has become.
The Journal of Irreproducible Results would not accept it. But that may have to do with the fact that any simulation is reproducible…
This is a very good example of PlayStation science, or how to produce papers playing with electronic gadgets without even lookig at their meaning.
A prerequisite for excessive warming in higher CO2 concentrations is that relative humidity (RH) remains constant, otherwise CO2 alone cannot produce enough radiative forcing. Constant RH implies higher water vapor in the atmosphere.
Thus, lets check some of the “non-livable” regions of the future, like Toumbuctu in Mali, in the Saharan desert, Asswan in Egipt, or Central Australia. In these regions wet bulb maximum temperature would reach 40°C. Current mean relative humidity is 25-35% (this is mean values, the actual value is smaller when they reach the maximum recorded temperatures). The important thing here is that the lowest the RH, the highest the actual air temperature must be to reach a given value of wet bulb temperature. Wet bulb T is defined as “the temperature an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporation of water into it, all latent heat being supplied by the parcel.” If we have to cool the actual air parcel and it has low RH we must cool it a lot to reach saturation. That means that for a very high wet bulb temperature with low RH, the actual air T should be extremely high.
Well, a simple calculation shows that to reach 40C wet bulb temperature in Toumbuctu or Asswan with 35% RH, the air temperature should be about 58°C, that is 18°C higher than the atual maximum values. Another interesting thing is that in that situation there would be condensation every night following the current daily temperature fluctuation. The amount of water from that condensation would transform the Sahara in a very nice garden. Remember that the same RH at higher temperatures means much more water vapour content in the air.
Not to mention the problem of finding the source of water for the increased humidity in the Sahara.
Can’t wait to see the actual paper and methodology…..
This reminds me a very good book by Vit Klemes, it was about hydrology, but it is equally applicable to climatology. The title of the book: “Common sense and other heresies”
Alan the Brit says:
May 5, 2010 at 1:40 am
It’s so humid here in Houston, we get dew on the grill when we barbeque brisket
Sorry to be Mr Picky, but it’s spelt, “barbecue”! :-))
Alan you are wrong, both spellings are acceptable
http://en.wikipedia.org/wiki/Barbecue
[BBQ, anyone? ~dbs]
It takes about 3 to 6 weeks to acclimate to significant changes in climate. Ask any soldier who spent time in Vietnam.
“While the Intergovernmental Panel on Climate Change central estimates of business-as-usual warming by 2100 are seven degrees Fahrenheit, eventual warming of 25 degrees is feasible, he said.”
Right. And the eventual sprouting of wings and flying of pigs is feasible as well. I have computer models which prove it. That’ll be a $million bucks please.
Uh, their emails are provided. Now, for all those who have a much more scientific background than me, and who can refute their (clearly bonkers) scenarios, can you please contact them and let them know?
The rest of us, chill out. And please don’t harass these folks just because you now know their emails. (On second thoughts, be alert to Warmists, masquerading as sceptics, crapping on them just to get us a bad name.)
“The study did not provide new evaluations of the likelihood of future climate scenarios”
Of course they didn’t. Who would look at a study where the likelihood was zero.
I didn’t bother to read any further.
Somewhere in my files I have a paper graph trace of my rectal body temperature in excess of 103 deg F for more than 4 hours, peak at 104.5, caused by infection of unknown origin. That was in Sydney, Winter 1983, not far from Uni of NSW.
BTW, the old-fashioned Scots nurse mumbling “Starve a cold, feed a fever” kept on adding more blankets. The external RH & temperature were governed by the hospital air conditioner. The latter part of the 8 hours above 100 deg F was in Intensive Care Unit in front of fans with wet towels draped over my naked skin. I lived. But it might have affected my mind. my mind. my mind. my mind.
Does this match up with the models?
These people are paid
governmenttax payers’ money to produce government propaganda. Do you think they might just have a little self-interest in producing such nonsense?Well,
I think it is really important for all of you to stop laughing at this.
My Great, great, great Uncle Earl graduated from Purdue in Civil Engineering.
He helped build railroads across Central and South America.
He helped advance civilisation. Like the route from Rio to Recife.
So, please stop laughing at Purdue!
Please don`t start stealing energy from my dimension,we would have to start burning magnetism to keep the thrittles kelouming…and we all know what that would lead to.
According to GISS, the globe has warmed less than 1C during the last 120 years.
It is NOT a legitimate possibility that this kind of warming will happen. They take an extreme scenario and then say it is a possibility when it is far outside even the IPCC predictions. Alarmism at its best!
When will they stop wasting our money?
Their goal is simply to alarm people.
Let’s all get worried that the plants will evolve rapidly to produce toxins specific for killing humans – a kind of vegetative revenge. Thus, we need to either marry a plant (everybody will have their own plant to nurture and protect) or wipe them all out in self defense. We will also have to find some other food source (meat is out) to make the plants happy, of it’s not too late. Better safe than sorry.
It is illegitimate for them NOT to (also) examine the effects of a 12 deg C DROP in temperature. That’s actually much more likely considering that we are overdue for an ice age and that the warm period peaks have been declining since the Holocene Optimum.
Idiots, all of them – an idiot defined as one who does not know what is going on around him/her.
Good grief
Juraj V: May 5, 2010 at 1:51 am
Net warming between 1945-2010, according to HadCRUT is 0.3 deg C. What is the physical mechanism, which will deliver 12 deg C warming in the future?
——————-
Positive CO2 feedback!!! Of course the fact that we’re around today despite CO2 levels and temperatures in geological history exceeding those of today is down to the knife-edge balance of solar output (30% less, but don’t ask me for evidence), water /ice /vapour albedo, oceanic coverage, volcanic ash and dinosaur gas which for some inexplicable reason managed to cancel out each other’s effects smoothly and continuously over time to ensure earth’s survival. Of course, as modern CO2 is man made as opposed to natural, most of the previously moderating factors have now become positive feedbacks instead. It’s the only way to account for what the models tell us..
“Fahrenheit? Who uses Fahrenheit?”
many of us colonials still have a fondness for it. Saying “wow! It’s a hundred degrees!” conveys is a much more satisfying way of saying “damn, it’s hot!” than “I can’t believe it’s 38 degrees out today!” does.
Regarding the original article, I think this is much more of a Dim Bulb controversy than a wet bulb one.