By Indur M. Goklany
It is well known that the risk of mortality increases at both the high and low ends of the temperature range experienced by a particular population.[1],[2],[3] Therefore, there should be a temperature at which that population’s risk of mortality is at a minimum. [There, however, may be more than one “local” minimum in a graph of mortality risk versus temperature as one proceeds from the lowest to highest temperatures.]
Recently, Guo et al. (2014) undertook a systematic evaluation of the variation in the risk of mortality from non-accidental causes as a function of daily mean temperature in 12 countries. The figures below display their results. They used mortality data for multiple years (ranging from 10 years for Thailand to 38 years for Japan) for 306 communities in the 12 countries, and pooled the data for the communities in each country to derive these figures.
Note that the temperature on the x-axis for each graph is measured in terms of the percentile of the temperature range rather than the actual temperature (in °F or °C). Also, their methodology was designed to account for deaths that occurred over the following 21 days, since additional deaths from exposure to hot or cold temperatures are known to occur for several days subsequent to actual exposure. [The period over which these deaths occur is longer for cold temperatures than for hot.] Their methodology also apparently accounted for “mortality displacement” or “harvesting,” which is the concept that temperature-related deaths that occur in a vulnerable population immediately following the temperature exposure would be partially offset by fewer deaths in that population over the following weeks.[4]
These graphs show that:
· The relative mortality risk for each country is at a minimum between the 66th and 80th percentile of mean temperature. Nine of the twelve countries have an “optimum” temperature between the 72nd and 76th percentiles.
· For each country the relative mortality risk is substantially higher at the 1 percentile temperature (cold end) than at the 99th percentile (hot end).
· Remarkably, the above bullet points hold not only for relatively cold countries such as Canada and South Korea but also the relatively warm ones such as Brazil and Thailand.
The study also reports that, “The minimum-mortality temperatures were higher in countries with high temperature or in countries close to equator.”
What all this means is that, first, because (a) there are more days during the year that are cooler than the optimum, and (b) relative risk is higher at the cold end than the warm end, more deaths should be associated with temperatures that are colder than optimum than those that are warmer. Hence, if global warming merely slides each curve to the right wholesale, total mortality during the year should drop. But, in fact, global warming is supposed to warm winters more than summers — even so-called Skeptical Science acknowledges this! Therefore, we should get a double dividend from global warming in terms of reduced global mortality.
Figure 1: Relative risk of mortality (y-axis) as a function of mean daily temperature plotted as the percentile of the entire temperature data. Data for each country was pooled. Source Guo et al. (2014).
In summary, there is an optimum temperature which minimizes mortality for any given population, and it is toward the warmer end of what that population generally experiences. Specifically, it is at about the 70th–75th of the mean temperature to which that population is exposed. Finally, if there is any doubt about it, there is a good health-based rationale for:
· The general preference for warm temperatures,
· For taking winter vacations in warm places and summer vacations in cold places,
· For retiring to warmer climes!
[1] McMichael, Anthony J., et al. “International study of temperature, heat and urban mortality: the ‘ISOTHURM’project.” International journal of epidemiology 37.5 (2008): 1121-1131.
[2] Keatinge, W. R. “Winter mortality and its causes.” International Journal of Circumpolar Health 61.4 (2002).
[3] Guo, Yuming, et al. “Global variation in the effects of ambient temperature on mortality: a systematic evaluation.” Epidemiology 25.6 (2014): 781-789.
[4] Deschenes, Olivier. “Temperature, human health, and adaptation: A review of the empirical literature.” Energy Economics 46 (2014): 606-619.
Note: an earlier version of this essay rfereenced the”y-axis” corrrected to “x-axis”. h/t to “joelobryan on March 2, 2015 at 2:49 am.”
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Interesting. It is unfortunate that quality of life does not correlate with longevity or mortality. I live at N45 for the agedness of my senior neighbors. Physically difficult lifestyles, lots of fish, low stress, good genes. I think I’ll stay here where the temperature is hovering well below the freezing point of water.
Our high GDP per capita and inexpensive carbon energy enables such lifestyle choices. Imagine your quality of life at half your wealth/income and 4x higher fuel costs. Obama and the Greens want us to experience both, whilst a political elite class of Al Gore, DiCaprio, and Obama retain their lifestyles.
I live at just North of N44, and think it’s great, but would not be nearly so impressed without gas snow blowers, chain saw and a 4WD pickup. In other words, a 19th century lifestyle up here might not make for a long and happy life.
Most of Canada starts at N49.
Yabut – 72% of the Canadian population lives south of the 49th. (Huddled freezing against the American border)
It’s also true that anomalous snowfall increases the birth rate….
But we all know the greens wish for higher mortality rates and lower birth rates.
Alcohol consumption is the leading cause of unintended pregnancies.
Global warming would be nice to go along with the increasing CO2. Not only would we have fewer people suffering from the cold, but we could have longer growing seasons to utilize the extra CO2. Alas, the possible, tiny amount of warming caused by the extra CO2 is likely to be insignificant in the face of a generally cooling climate.
Answer — 60 to 80F, with an avg of 70F. So Gorebull warming needs to go up about 20F here for an optimum climate.
Here in western MD, the Hagerstown MD observer (I’m 60 miles west of him and a couple degrees colder) had an avg Feb temp of 23.2F — fourth coldest since 1898. That’s a whopping 10.3F below avg for Feb.
Here in Finland, Feb 2015 has been 5 – 7 degrees C warmer than by average. That is 9 – 12F.
Not that I’d complain much, but local weather is just local weather.
Oh, and by the sound of it, it is currently raining (or drizzling) like it has been much through the winter. Now if this is what global climate change does, it is really boring and depressing, but you can’t call the weather hot by any means.
We evolved in the tropics and shed our “fur”. Should be a no brainer
This doesn’t appear to be the case for Italy.
not every country shed their fur.
@soarergtl March 2, 2015 at 2:55 am
<i…
“A culture where the young girls go out night-clubbing with minimal clothing is likely to suffer if the weather gets cold.”
You can easily disprove this theory by going to Newcastle-upon-Tyne, UK (Newcastle NSW may be different). There, on any winter weekend, you can see girls in minimal clothing and men in T-shits, complaining that the snow is too hot. The only physiological change I can determine is that the girls legs, if not fake-tanned, are a rather fetching blue colour….
Ah, well – lets look at the mortality statistics.
Cardiovascular disease health profile – Newcastle upon Tyne
Early cardiovascular mortality (<75 yrs)
Newcastle 73.5
England Average 58.8
My hypothesis is proven! (using the approved Climate Change argument that we can't think of anything else it might be…)
i’m a mainer (so temps in F) and I like it 71 in summer with low-medium humidity and 25 with no wind in winter.
@ur momisugly berniel March 2, 2015 at 2:25 am
I recall Richard Tol claiming in one blog debate that there is an optimum climate and it is the climate of Florence….
So… We’re paying all this money to convert the entire world’s climate to that of Florence?
I don’t think we’re spending enough…
Winter
We’ve had a first sprinkle of snow. It came last week. Today was cold and I was lovingly reminded to wear a hat. Winter is waiting. This poem by Julian Tuwim is in anticipation.
Winter
by Julian Tuwim
Six O’Clock dark,
A cold day begins,
The rattle in the park,
Of clattering tins.
Clank on cobblestone,
Slowly and far.
In grey-bluish tins,
Milk gurgles in its jars.
Horses blow mist,
The people shake,
Wagons persist,
Hard-hobbling awake.
Six O’Clock dark,
A cold day begins,
Comes into my dream,
The drum-roll of tins.
In a sheepskin jacket,
I doze on the bench,
Breathing like a mother,
In my frost dream’s clench.
My life in dreams,
Frozen in flight,
Engulfed by spluttering,
Milky and white.
White and warm,
A motherly gurgle,
Comforts me, hides me,
Beneath the burqa of winter.
Now I’ve been begun,
Already I’m starting,
Gasping-meandering,
In this maternal dream.
In a faraway milk,
An echo sways,
The wagon rumbles,
Still quieter, farther away.
http://paczemoj.blogspot.com/2010/11/winter.html
A question that should be even more important to those who worship the creation rather than the creator would be “what is the optimum temperature for the present biosphere.” But alas, in their rush to impose new taxes and laws that grow government and reduce personal liberty in order to mitigate climate change, progressives don’t have time for that question. I wonder why?
Probably explained by influenza season in the temperate regions associated with winter and the rainy season associated with the cooler weather in the tropics.
It seems like there should be further study into the correlation for the countries that appear to show a high dependence of morality on temperature, i.e. Italy, Taiwan.
Fair enough that there should be a minimum around 75% of the temperature range – “we like it hot”. But why should there be a half-hearted attempt at a minimum at around 25% of the temperature range? Is this an artifact of the statistical process (like that silly hockey stick – or is there an (unstated) valid reason for this?
For those who mentioned the possibility of hair loss as due to water, suggest you get hold of a copy of “The Descent of Woman” by Elaine Morgan. She wrote a pretty good non-technical introduction to the Aquatic Ape hypothesis. Pooh-poohed by academics as she was a writer, not a university lecturer/researcher; they dismissed her views. Just like crusted-on Professors of Alarmism decry the views of intelligent sceptics. Same old, same old. Oh, dear, when will they ever learn?
I didn’t have time to read through all the “thoughts” above, but seems allowing the average to increase would exchange people saved from the cold with people killed by the heat.
And there seems to be a bias on the graphs, what with them being most from places that have winters, Thailand and Taiwan excepted. What about places like India which has no cold weather but lots of hot.
trafamadore, read about what global warming hypothesis says about where the greatest warming will occur. Read Golkany’s post again, carefully.
I will assume that you mis-spoke (wrote) there. The Himalayas, with its glaciers, span five countries: India, Nepal, Bhutan, China (Tibet), and Pakistan.
And what % of indians have ever seen snow? Not many. For sure, none of the Indians I know, and that’s a few. But you miss the point of my post (how unusual at whats up): people in warm climates don’t see cold weather. So you make things worse for them, and I think that is the majority of the people in the most populated places on earth.
It’s arguable that the temperature range of the very stable Holocene is “optimal” for human life. It’s not clear that warmer temperatures, like those of say the Eemian would be necessarily better or worse, though the 6-8 m higher sea levels should prompt one to think about coastal infrastructure. One thing which is pretty clear to me: sustained wet bulb temperatures above 35 °C are pretty much 100% fatal, though much depends on amplitude, duration and individual fitness — an hour in the sauna pouring water on the hot rocks won’t get most people, but a week of that would slow cook anyone for sure. That’s resting metabolism. Add hard physical labor to the mix — say working a rice paddy — and the danger threshold gets even lower.
Or another way of putting it, the closer to 35 °C wet bulb temps, the lower the labor output. Plants may very well grow like gangbusters at 560 ppmv CO2, but a lot of staple foods come from parts of the world where few have ever seen a combine harvester in the flesh, much less an air-conditioned one.
Luckily getting 35°C 100% RH is pretty distant.
+1°C out right now. The humidity is 99% RH, but absolute humidity is lower. Lets return to the case after Great Britain starts producing bananas.
Hugh,
The OP asks what the optimal temperature is. Given the inherent uncertainties in projecting the as-yet unexperienced future, setting an upper limit by way of wet-bulb temperature seemed appropriate.
Even the worst-case AR5 projection doesn’t get there by 2200, however it’s not necessary for 100% of the surface to experience those kinds of temperatures to be potentially disruptive: http://www.gfdl.noaa.gov/news-app/story.77
http://www.gfdl.noaa.gov/pix/news/labor_capacity-1.gif
Yah, models. Keep in mind they could be wrong on the conservative side. Personally, I’d rather not find out empirically — we know a lot better how crops and field laborers do in the present regime than forward-looking computer simulations are ever going to be able to tell us.
I’m sure the folks at the Weather Channel would find that quite topical.
People migrating poleward from the tropics are going to need to live somewhere. Better hope CO2, oh, quadruples those banana yields. And does the same for rice, wheat and corn. And that the models you’re using for those estimates are better than the whiz kids at GFDL have done.
Brandon,
The thing is I really can’t take the models seriously. After tweaking them to not do runaway ice age or boiling, they don’t make me feel they describe the earth. Why could I not be wrong. On the other hand, I’ve not been particularly impressed on successful predictions based on them.
I have today here probably 2-3 C warmer year than when my great-grandfather suffered the extremely cold summers. That is not a bad thing. I have great difficulties seeing any trouble in the next 2-3C, should it come. And that’s mostly the arctic winter. Summers are less affected, partly because clouds will cool a summerday, when during the winter they make it milder.
I know mentioning the days temp is off topic, it is just very difficult to see how on earth you could get this planet so hot throughout these northern latitudes.
Thailand OTOH is very much 35C/100%RH already today.
Hugh,
What I won’t take seriously are arguments along the lines of, “the models suck” followed by “we’ll adapt”. It’s not a logically consistent position.
Your personal incredulity is something only you can overcome for yourself. I look to data, and they tell me that high northern latitudes are warming faster than the rest of the planet as per predictions from paleoclimate observations.
Not according to this paper: http://www.pnas.org/content/107/21/9552.full
… the highest instantaneous TW anywhere on Earth today is about 30 °C (with a tiny fraction of values reaching 31 °C). The most-common TW(max ) is 26–27 °C, only a few degrees lower.
And not according to common sense either. Sustained wet bulb temps above 35 °C are simply not survivable without air conditioning. A fan won’t cut it.
What boggles my mind is this: if you actually think Thailand is that close to the survivability limit, why on Earth would you be content to allow things to get even warmer? Do you just not get it that I’m NOT talking about the kind of heat that drinking more water and taking a few salt pills can handle?
Humans maintain a core body temperature near 37 °C that varies slightly among individuals but does not adapt to local climate. Human skin temperature is strongly regulated at 35 °C or below under normal conditions, because the skin must be cooler than body core in order for metabolic heat to be conducted to the skin (17). Sustained skin temperatures above 35 °C imply elevated core body temperatures (hyperthermia), which reach lethal values (42–43 °C) for skin temperatures of 37–38 °C even for acclimated and fit individuals (18, 19, 20, 21). We would thus expect sufficiently long periods of TW > 35 °C to be intolerable.
Again, that assumes a resting metabolism. As in NOT doing intensive manual labor outside in sunlight harvesting YOUR food. As in, the WBT does not need to reach 35 °C for it to be an incrementally costly problem.
Dr. Goklany takes an incredibly narrow view of the human condition. Climate change will cause all kinds of disruptions to economies (droughts, extreme winter weather, sea level rise, etc.), with many direct and indirect impacts on health and mortality (or premature mortality, for all those who point out mortality is 100%), but apparently he is not capable of any kind of systems thinking. Also, there are many people on the planet who don’t have the luxury or vacationing or retiring to warmer climes. This is an example of a 1%-er using about 1% of his brain. Just pure stupidity.
I agree that climate change will cause issues. When the interglacial ends, billions will die. Even a mega-drought or another Bond Event would kill millions. Such things will happen for sure.
For sure? You know this … how? How soon is this next ice age you’re 100% confident of?
Climate change will cause all kinds of disruptions to economies
====================
so lets stop using fossil fuels because that for sure wont disrupt economies. all that extra cash we will all have in our pockets, not having to spend it on oil and gas. instead we can burn it to stay warm.
Speculative drivel from you with no evidence. This “is an example of a 1%-er using about 1% of his brain. Just pure stupidity” from you. Your rant is not evidence. It’s BS.
Cheers!
Jimbo, this just out today: Climate change implicated in the recent Syrian drought and current conflict.
http://www.pnas.org/content/early/2015/02/23/1421533112
Ask any older person (such as myself) you’ll find that their tolerance for lower temperatures is less the older they get. (Florida isn’t a retirement target just because of taxes).
I need a higher temperature when just sitting around. Feel more easily chilled with lower temps.
I keep asking “Where’s all this Global Warming I’ve been promised”?
Can I sue Al for breech of contract or false advertising maybe?
“Hence, if global warming merely slides each curve to the right wholesale, total mortality during the year should drop” does not follow from ” “The minimum-mortality temperatures were higher in countries with high temperature or in countries close to equator.” What would happen, would be that the characteristics of the mortality-temperature curve would change.
That’s really bad news for the warmists who believe that fewer humans is the goal of climate regulations.
Forecast polar vortex (yes, they are very good forecasts) shows the dipole consistent with the two centers of the magnetic field in the north.
These are still very wrong forecasts for Canada.
http://www.wetterzentrale.de/pics/Rhavn1803.gif
Click the graphic.
If we want to move beyond constantly reacting to BS spewed by AGW fanatics, we need to seize control of the conversation. There are real threats related to the climate. Namely, mega-droughts and the eventual end of the interglacial. Even barring the end of the interglacial, another 1814 would be no picnic. Discuss these issues, discuss plans to mitigate their impacts, force the media and public officials to confront them.
During Tuesday, accumulating snowfall will fall from Wyoming and northern Colorado to South Dakota, northern and western Nebraska, northern Iowa, much of Minnesota, Wisconsin and northern Michigan.
http://vortex.accuweather.com/adc2004/pub/includes/columns/newsstory/2015/650x366_03020934_hd35.jpg
I’m suspicious.
Note that only three countries have a great increase with high temperature, and they aren’t especially hot countries nor especially poor ones where other factors could be in play. (Italy, Spain, and Taiwan.)
By 0% of the temperature range, do they mean absolute zero? I’m a bit surprised the mortality risk isn’t even a bit higher.