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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Hey, “National Academy of Sciences” – isn’t a situation like what you propose what air conditioners/humidifiers for?
(I’m in a rush.)
James Sexton says:
May 5, 2010 at 12:56 pm
James, you obviously are still not comprehending the rules and procedures. Corrections to the record are only allowed if they show temperatures that are too LOW, except of course, if they are far enough in the past. In which case we will correct them whether there is any evidence to show they were in error or not.
It’s all very complicated and unless you have a double doctorate in climate science and the literature of Steven King it’s not really worth taking the time to explain it to you. You just send us the check and then you can go out and play with the other children, we’ll take care of everything, we promise.
And I thought wet bulb meant this thing from EternalLEDs
Dave Wendt says:
May 5, 2010 at 1:31 pm
James Sexton says:
May 5, 2010 at 12:56 pm
James, you obviously are still not comprehending the rules and procedures. Corrections to the record are only allowed if they show temperatures that are too LOW, except of course, if they are far enough in the past. In which case we will correct them whether there is any evidence to show they were in error or not.
It’s all very complicated and unless you have a double doctorate in climate science and the literature of Steven King it’s not really worth taking the time to explain it to you. You just send us the check and then you can go out and play with the other children, we’ll take care of everything, we promise.
lol, I agree, and once again showing our earlier thinkers correct, “I prefer the company of peasants because they have not been educated sufficiently to reason incorrectly.”
Michel de Montaigne
Richard Holle says:
May 4, 2010 at 10:42 pm
“Wet bulb temperatures are the dew point of the air, no more no less.”
Utterly incorrect. Back to Met kindergarten for you. No wonder the warmistas treat this site as rubbish.
[Reply: You’re using inductive logic, cementhead, an alarmist trait.]
I have modelled the effects of a 7 to 12 degree temp increase on the common mosquito. My conclusion is that a higher temperature environment has an exponential effect on growth rates of mosquitos and this will possibly result in mosquitos evolving to a wingspan of 4 feet or more within the next century. The climate model used to arrive at this was the same as one used in the wet bulb study itself. The predicted wing span of the hot weather mosquito was derived from a similar computer model that used no experimental data at all, a truly major achievement in the advancement of computer modeling techniques. I allow that, as some of my critics point out, the Square Qube Law requires that a mosquito of this size would collapse of itz own weight, but as physics parameters were excluded from the model this has no bearing on the final result.
While no modeling on behaviour was done, it follows that due to increased size the mosquitos will be more agressive and territorial, defending any prey from other mosquitos due to the dwindling supply by mass comparison. The possibility that this will cause mosquitos to seek weaponization tools is a real consideration.
I note that other post normal entomologists have suggested the giant mosquitos would be kept under control by similar processes resulting in helicopter size dragon flies. I will only respond that the mere notion of a helicopter sized dragon fly is patently ridiculous, and should be dismissed out of hand as having no basis in science.
Alan the Brit says:
Mike McMillan says:
. . .we get dew on the grill when we barbeque brisket
Sorry to be Mr Picky, but it’s spelt, “barbecue”! :-))
Ahem – Not that we trust Wikipedia, but
Barbecue – Wikipedia, the free encyclopedia
Barbecue or barbeque (common spelling variant) (with abbreviations BBQ, Bar-B-Q and Bar-B-Que; and diminutive form barbie, used chiefly in Australia and New …
And we don’t spelt in Texas.
http://pielkeclimatesci.wordpress.com/2010/05/04/update-to-andy-revkins-question-in-2005-is-most-of-the-observed-warming-over-the-last-50-years-likely-to-have-heen-due-to-the-increase-in-greenhouse-gas-concentrations%E2%80%9D/
Seems that natural variation is up to the task, unless you view Spencer as a creationist or something.
Sherwood said. “Although we are very unlikely to reach such temperatures this century, they could happen in the next.”
Lucky fellow! You will long be dead before that and you’ll be spared the embarassment of listening to people laughing at your predictions!
Back on January 3rd, 1975 (hottest time of the year), after a week of torrential rains and floods in La Rioja province, Argentina, in the capital city was recorded 48ºC with a 90% humidity, way above of what this moron Sherwood states as dangeorus wet bulb temepratures.
Amazingly -and sadly- , all those hundred of thousands of horrible, greedy, fossil fuel burners managed to suvive until now. Mother Gaia must be quite sad she failed at eliminating her cancerous tumor.
Eduardo Ferreyra says:
May 5, 2010 at 3:27 pm
Do you have a reference for that? That makes for a dew point of about 46ºC and a wet bulb temp slightly above that, 10ºC above the Saudi Arabia world record dew point. I bet that 90% was recorded overnight and that the wet bulb temp at the time was in the livable range.
I tried find some La Rioja weather records on the web, but failed. Perhaps they’re all in Spanish.
I did the same, and after reading the humorous FAQ’s in Sherwoods CC Research Unit I started to feel that they sense that the game is up, that the AGW Orbiter has lost altitude, is slowing and just starting to burn up in the upper atmosphere.
The problem I see is, where is the oversight to critically review this nonsense before it is published ? It shames the Universities that they have allowed this to be published under their banner.
Really? I do long distance backpacking in the desert at temperatures of at least 95 degrees all the time. On many backpacking adventures, I’m on the trail for three to four days not only exposed to the heat but exerting myself in it. Sure, I stop for breaks, carry plenty of water, wear UV resistant long sleve wicking clothing and pants, etc… but I figure if the potentially lethal heat I’m exposing myself to hasn’t killed me in 40 years, it probably isn’t all that lethal.
With the above said, I may just be acclimated to the heat but wouldn’t non-hikers acclimate to 95 degree temperatures over time too? I can’t help but feel this is yet another “we’re all gonna die” proclamation based on flimsy assumptions and flawed reasoning.
Climate World model is a jar with a lid and no moving air.
In Climate World, the human body is a homogeneous lump of gelatinous material with the core heat transferring to the outer layers
In Climate World we have no circulation – just like Climate World Earth.
Phyorg.com published this prominently. I’m sad that they have degenerated so far and hope an intervention might save them.
I have to say, after sitting in an astronomy and geography course for the last week, this is what college professors, almost without exception, advocate. For example, the ice age predicted in the early 70’s was averted because we are pumping out so much CO2. That mussels, clams and oysters are in danger of extinction due to rapid acidification of the ocean as all this excess CO2 has no where to go. That we are in real danger of becoming another Venus….I’m older, somewhat more aware than the average college student. The level of outright …propaganda is nearly overwhelming.
To PHYSorg_Support –
Dear Mods and Whoever actually cares about the future of this site:
I’m no longer able to tolerate association with this site as it has degenerated from a once fine aggregator of recent journal publications into a shill for cargo cult science.
Where highly speculative and uninformative articles may be interesting on occasion, they are fiction.
Where highly speculative and patently absurd doomsday scenarios are presented AT ALL, the character of the site which hosts it is defined immediately and significantly.
The fools pushing the awg agenda have cost you your reputation for quality.
You are now reliably trashy.
I’m saddened by this, as I will no longer mention the name of your site despite the regular occurrence of good articles – because they no longer define the character of this place.
Sorry, but you’re too bad to remain associated with in any way.
Seek intervention. I wish for your recovery, but I know that the prognosis is a death spiral of delusion. If there are no rational individuals protecting the interest of this site, it must fail.
Luckily humans invented air conditioning and dehumidifiers. We’ll be fine.
Hank Hancock says:
May 5, 2010 at 6:02 pm
Name me one desert that has wet bulb temperatures above 95°F. (Besides the Persian Gulf!)
In 2003, my family went on a bicycle tour that included the high desert of Central and Eastern Oregon. Several days were over 100°F, but I’d guess the dew point was under 45°F. That corresponds to a wet bulb temperature of only 67°F.
For a wetbulb temp of 95°F you need something like 120°F and dew point of 90°F. You didn’t say where you go backpacking, but I don’t think those conditions exist in the United States for more than six hours at a time.
Well Purdue can forget any alumni donations from me if this is the type of idiotic stuff they are producing. And to think just this weekend I recommended a high school senior checkout Prude U – – -No more recommendations either.
Nice glacier you got there, friar.
Be a pity if something happened to it.
Dave McK says:
May 5, 2010 at 6:42 pm
To PHYSorg_Support –
Dear Mods and Whoever actually cares about the future of this site:
I’m no longer able to tolerate association with this site as it has degenerated from a once fine aggregator of recent journal publications into a shill for cargo cult science.
Where highly speculative and uninformative articles may be interesting on occasion, they are fiction.
Where highly speculative and patently absurd doomsday scenarios are presented AT ALL, the character of the site which hosts it is defined immediately and significantly.
From the PR that inspired this post
“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.”
I assume you have forwarded a similar message of disavowal to the publishers of the POS… excuse me PNAS.
As one who’s own attempts at irony and satire have managed to crewcut the crowd around here on a regular basis, as they whizzed by overhead, I apologize if I’ve been similarly slow on the uptake of your own effort at humor. If, however, you were in fact serious in your post, I can only say for myself, as I would never presume to speak for others here, “don’t let the screen door hit you where the Good Lord split you!”
Had I paid attention to the wet bulb part I wouldn’t have made such a foolish mistake. Thanks for sorting me out. I hike in the Nevada, California, Utah, and Arizona desert areas. Several times thorough the Grand Canyon in the summer and a few times in Death Valley. So I’m figuring that with the normal humidity ranging between 8% – 12% in my parts the temperature has to get incredibly hot reach a wet bulb temperature of 95 degrees.
Would a dim bulb be warmer than a wet one?
Dave Wendt says:
May 5, 2010 at 8:14 pm
Dave McK says:
May 5, 2010 at 6:42 pm
To PHYSorg_Support –
Sorry Dave I missed the PHYSorg salutation and misinterpreted your comment. You have my apology.
These are the headlines I am now expecting over the next few months:-
“Human heads to explode in warmer climate!”
“Nuclear warheads to be detonated by global warming!”
“Surge in paedophilia expected due to global warming!”
“Murder rate to increase as earth warms!”
“Statue of Elvis found on Mars!”
I like the one my grandmother used to use.
It’s so hot families are out BBQ’ing on their sidewalks!
Oh. That’s right. Mustn’t indicate sidewalks were hot enough to fry eggs in the past mustn’t we.