Guest essay by Roger Graves
Predictions of atmospheric CO2 levels at some future time are commonly made, usually with the object of assuring us that beyond a certain point our planet will be fried to a crisp. Most of these predictions are in the form ‘if CO2 levels reach x, the effect will be such-and-such’, without actually indicating why CO2 levels should reach such a value. However, it is possible to make an accurate prediction of future CO2 levels using readily available information.
The graph shown below plots CO2 levels as a function of world population, encompassing the period 1960 to 2015. Note that although each data point represents an individual year in sequential order, time is not explicitly represented on this graph, which merely shows how CO2 levels are related to overall world population.
It is reasonably obvious to the naked eye that CO2 and population seem to move in lockstep. To show this in more analytical terms, we can superimpose a trend line, which is simply a mathematical curve which fits the data. After some experimentation it was found that a trend line consisting of a third-order polynomial provided a very good fit to the data. In statistical terms, the R2 value for this curve is more than 0.999, which indicates that it correlates with the data to an accuracy of better than 99.9%.
One advantage of a trend line is that we can then extend it to make predictions of what the future may hold, which you can see in the chart below. Both axes in this chart have been extended for this purpose.
Of course, the same graph could have been drawn with CO2 levels on the horizontal axis and population on the vertical axis, so that population would be shown as the dependent variable and CO2 as the independent variable. The same correlation between the two would still exist.
The question that now arises is whether population is driving the CO2 level, or CO2 is driving population. There are four possibilities to be considered:
1. There is no connection between the two, the apparent lockstep is just a fluke. Possible, but very unlikely. This possibility can reasonably be ignored.
2. Population causes CO2. This is ‘obvious’ explanation that most people would give. The more people there are on our planet, the more CO2-generating activities there will be, such as electrical power generation, industrial activity, automobiles, cooking fires, and so on.
3. CO2 causes population. Much of the population growth in the foreseeable future will come from sub-Saharan Africa. Population growth in these regions is dependent to a large extent on the food supply, and as we know, crop yields increase with CO2 levels. The greater the food supply, the more children will survive to maturity.
4. The connection between CO2 and population results from some, as yet unspecified, combination of 2 and 3.
My personal view, and this is only an unsupported guess, is that possibility 4 is the most likely.
What conclusions can be drawn from this? First, the population/CO2 curve is a smooth curve. No evidence is shown of any significant decrease in the inexorable rise of either CO2 or population from beginning to end of this curve. We can conclude from this that none of the measures taken by industrialized countries to reduce CO2 output have had any noticeable effect, nor does it appear likely that they will have any significant effect in the foreseeable future.
Second, current UN population projections indicate that we will reach a population of 9 billion by 2038, and 10 billion by 2056, using the medium variant of their three prediction levels. (To follow this further, go to http://esa.un.org/unpd/wpp/Download/Standard/Population/, then download the spreadsheet called Total Population – Both Sexes.) Assuming that the population/CO2 relationship still holds good by then, we can predict a CO2 level of nearly 460 ppm by 2038 and 500 ppm by 2056.
Population growth is a quantity which can be reasonably well predicted for one or two decades into the future. While extrapolating a curve in order to make predictions is always fraught with danger, based on the data so far I am fairly confident that the CO2/population relationship will hold for a few years yet. In the long term of course, your guess is as good as mine, but I think we can reasonably well predict CO2 levels in the range 450-500 ppm by the middle of this century. Whether the world then disappears in a puff of smoke, or enters a new golden age of unsurpassed crop yields, remains to be seen.
Roger Graves is a physicist and mathematician who, much to his chagrin, is not associated with big oil, big coal, or big anything else.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Population growth doesn’t directly cause CO2 levels to increase.
So why would you put both of them on a chart?
Also, extending trend lines is nonsense.
You should know better.
Predicting the future is usually a waste of time.
You should know better.
If the point of your post was to “prove” humans are adding CO2 to the air, we already knew that.
The important question is whether the added CO2 is good news or bad news.
I submit there is no scientific evidence that adding CO2 to the air is bad news, and a lot of evidence that adding CO2 is good news.
I believe adding CO2 to the air, and greening the Earth, was (inadvertently) the best thing humans have ever done to improve our planet.
The next step is to clean up the dirtiest forms of combustion that add CO2 to the air — mainly in Asia now — but not to stop adding CO2 — greenhouse owners know a lot more CO2 will accelerate plant growth — and accelerating plant growth will help feed those who are malnourished or starving,
So I guess you could say my “theory” is adding CO2 to the air accelerates green plant growth, which helps increase the food supply, which allows our planet to support more human life.
Burning fossil fuels helps keep us alive.
Indeed, all that carbon in the ground (coal, oil, gas) was once in the air. We are just liberating it.
A new political movement: The Carbon Liberation Party.
Why leave carbon in the ground, or ocean, if plants want it, and need it?
Well Richard, I’m happy to see that not everyone is taken in by the pretty pictures.
You can make a scatter plot with any two sets of numbers, whether they are related or completely unrelated.
Excel will do it for you.
Some such plots are pretty; others are scruffy. That’s why they are called scatter plots.
No matter how pretty they are, it doesn’t prove any causal relationship, or establish any expectancy for the consequences of extrapolation, outside those two sets of numbers.
G
My take on this post is that there appears to be a strong correlation between population and CO2. So, if one assumes that the climate models are correct and CO2 = global warming, then it follows that climate control = population control.
I suspect it is almost all because of Option 2. Every human has a carbon dioxide footprint. The more humans, the bigger the collective footprint.
The other options are minor or non-existent.
I also assume that footprints will decline due to efficiency over the next few decades and the UN will over-forecast population. This combination puts us at about 450ppm by 2050
Mary, you do realize don’t you that with your belief, you must also accept that the ENTIRE growth in atmospheric CO2 abundance must be due to humans.
I don’t know of anyone who believes that humans alone are entirely responsible for all of the CO2 above 280 ppmm in the atmosphere.
G
‘cept ferdinand…
George,
You said, “I don’t know of anyone who believes that humans alone are entirely responsible for all of the CO2 above 280 ppmm in the atmosphere.”
I guess you really don’t know me or Ferdinand. However, am I to understand that you believe that it is entirely a coincidence that the scatter plots that Graves and I produced show such a high correlation between the population and CO2, both of which are increasing?
1960, CO2 levels approx. 300 ppmv that’s a very dangerously low level.
Well actually for the ML data it was 315 ppm in 957/58, the year of the International Geophysical Year (IGY).
G
Naw, more people means more people are breathing out CO2. Causation found!
The slight warming has been beneficial for both humans and plants, which is also good for humans.
The rise in CO2, probably mostly caused by humans has been beneficial for plants, which is good for humans, who then produce further CO2.
Uh-oh, I see a problem. Paradise on earth, Garden of Eden style. No need for God then. Can’t have that.
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQcxbHdiprETnBzoy6ABoaKvsVFT7a1LJk4cFXcjYYLHH8opX_BfH2qzVA
http://www.tutor2u.net/blog/files/blog-correlation-291209.gif
http://i.dailymail.co.uk/i/pix/2014/05/28/article-2640550-1E45C57300000578-400_634x281.jpg
http://i.dailymail.co.uk/i/pix/2014/05/28/article-2640550-1E45C92800000578-662_634x267.jpg
http://www.tylervigen.com/spurious-correlations
Any two variables in a rising trend will have good positive correlation.
Any two in a declining trend too.
The variables don’t have to be related in any way
This graph is data forcing in it’s purest form… the data point MUST match a population in that layout.
I compiled the following statistics via reliable sources, to wit:
Increases in World Population & Atmospheric CO2 by Decade
year — world popul. – % incr. — Dec CO2 ppm – % incr. — avg increase/year
1940 – 2,300,000,000 est. ___ ____ 300 ppm est.
1950 – 2,556,000,053 – 11.1% ____ 310 ppm – 3.3% —— 1.0 ppm/year
1960 – 3,039,451,023 – 18.9% ____ 316 ppm – 1.9% —— 0.6 ppm/year
1970 – 3,706,618,163 – 21.9% ____ 325 ppm – 2.8% —— 0.9 ppm/year
1980 – 4,453,831,714 – 20.1% ____ 338 ppm – 4.0% —– 1.3 ppm/year
1990 – 5,278,639,789 – 18.5% ____ 354 ppm – 4.7% —– 1.6 ppm/year
2000 – 6,082,966,429 – 15.2% ____ 369 ppm – 4.2% —– 1.5 ppm/year
2010 – 6,809,972,000 – 11.9% ____ 389 ppm – 5.4% —– 2.0 ppm/year
2015 – 7,349,472,000 – 07.9% ____ 401 ppm – 3.1% —– 2.4 ppm/year
Source CO2 ppm: ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_mm_mlo.txt
Based on the above statistics, to wit:
Fact #1 – In past 75 years – increases in world population per decade shows no correlation between increases in atmospheric CO2 ppm per decade.
Fact #2 – Atmospheric CO2 has been steadily and consistently increasing at a rate of 1 to 2 ppm per year for the past 75 years, …… whereas human generated CO2 releases have been increasing exponentially every year for the past 75 years.
Fact #3 – Global Average Ocean Surface Temperatures have been steadily and consistently increasing a few hundredths or tenths of a degree for the past 75 years, ……. whereas human created infrastructure, housing, vehicles, etc. (Heat Islands) and the quantity of fossil fuels being burned ……. have been increasing exponentially every year for the past 75 years.
Conclusion: the gradual warming of the ocean waters during the past 75 years is the “driver” of the gradual increase in atmospheric CO2 ppm quantities.
You had me going there, for a moment — all that pseudo-logic and math.
I added up all the numbers, and the total made no sense to me.
While many people will think your comment is cool, calm, and logical,
I DID NOT SEE the obvious conclusion:
Life on Earth will end as we know it
If anything, we may be postponing the return of tne glaciers, which is due anytime soon. You want to see theend of life as we know it, just wait till then. Might be a few or tens of thousands of years, though, so don’t
be impatient.
Richard Greene said:
Well now, Richard, at least you got that part right.
There were no numbers in my above post that could have “made sense” iffen they were added up.
Those numbers represent: Increases in World Population & Atmospheric CO2 by Decade
By Decade, Richard, ….. by Decade.
Note to Sam Cogar:
“I added up all the numbers, and the total made no sense to me.”
That was a joke, Sam.
My whole post was meant to be funny.
I should have just commented that your post was excellent, because it was.
However I was in a mood to not take any real climate science seriously, and tried to be Rodney Dangerfield in my comment.
I am obviously not Rodney Dangerfield, although my wife often compares me to him:
She always says: “You look just like Rodney Dangerfield.”
I now realize attaching my humor post to your serious post was a mistake, like dog excrement on the heel of an expensive shoe, and if there was any way I could remove my prior post, I would do so … assuming you would be willing to pay me enough money.
Oh, and keep up the good work.
1. Roger Graves says it
is possible to make an accurate prediction of future CO2 levels using readily available information.
The graph shown below plots CO2 levels as a function of world population,
2. Assuming world poulation means ‘human population’ ~2 mil ys
3. CO2 levels on this planet change ~4.3 bl ys
4. Roger Graves does’nt mention ‘warming’
5. watch Steve Mosher stick together
CO2 levels; 2 mil human / 4.3 bl worlds; add some ‘warming’ -> here we go
kind’a Freudian fixation –
human / warming / CO2
Leaves the question –
how does ‘sea level rise’. Without us.
How came cancer into the world. Before Glyphosat urin Tests.
And before EPA.
It is quite surprizing and as well shocking, how the reports presents such a beautiful graphs — population versus CO2, when the data availability is unreliable and inaccurate?
Dr. S. Jeevananda Reddy
cont— why I said that is, we have seen hundreds of papers saying CO2 is contributed by Agriculture, animals, etc, etc. are these bogus studies!!!
Dr. S. Jeevananda Reddy
Wouldn’t it be more informative and helpful to look at the actual CO2 levels above human cities using the new CO2 detection sensors on orbiting satellites? As I recall, from the early photos, the higher concentrations of CO2 had very little connection to human cities, except in northeast China. It appeared like there was a much closer connection between higher CO2 concentrations and effects of relatively warm summer temperatures, which caused decaying biomass on land and out-gassing in the relatively warm ocean water.
Call me crazy, but I say we take a look…
You can look here:
http://www.climatecentral.org/news/city-tailpipe-emissions-18861
and many other around the world.
This site shows maps of urban sprawl. I’m not claiming cars and electrical generation doesn’t cause some emission of CO2. I’m talking about how that CO2 stays or does not stay in the atmosphere. I’m talking about a picture from space about the actual CO2 concentrations. And, from my recollection of the early views, they don’t mesh with your urban sprawl maps.
RD50, look at this satellite remote sensing image and then tell me that high CO2 correlates with urban sprawl.
http://www.livescience.com/49196-nasa-satellite-oco2-carbon-maps.html
To Mike Reno at 9:25
High CO2 is created in urban sprawl. This is where energy is consumed. Your oco2 carbon map does not refute the fact that CO2 is created in urban sprawl, just as it is created everywhere else. Your map does not indicate where the CO2 is created. Then look at your map again, see how much difference there is between the low and high concentrations. You think this indicate where CO2 is produced? And why no update of this old map?
Mickey Reno sayeth:
Mickey, there are no CO2 detection sensors on orbiting satellites. NONE, NADA, ZILCH, ZERO.
The satellites you are referring to are affixed with IR sensors (infrared radiation) that can detect and measure the intensity of IR radiation that is being radiated from the earth’s surface/atmosphere toward outer space where said satellite is orbiting.
The satellite can detect the IR radiation, ……. but the satellite can’t “see” what the source of that radiation is or was.
Quoting the author of this post;
“One advantage of a trend line is that we can then extend it to make predictions of what the future may hold,”
Well…. the operative word in your sentence is of course “MAY HOLD”…
Sure, it could all work out exactly as you predict, or it could all go in a totally different direction….
Who thought the “Great Depression” could occur after a stock market crash…. Heck all the wise predictions of what MAY happen where quite sure that the “roaring twenties” would just keep on rolling…..
And then there was that whole Dictator thing going on in the 1940’s…. Who knew that crazy people (Hitler was a documented Meth addict) could gain total control of the government of a previously civilized country (the Germans did contribute a great deal to chemistry, music (Wagner), and culture)…
Extend your carefully crafted trend-lines at your own risk my good man, those of us that use curve fitting techniques to implement actual real world solutions to actual problems insist on some proof of causation before we wander off into the curve fitting weeds…
I can fit third, fifth, seventh, ninth and other order polynomials to the supplied data and make any “future” prediction you desire. Heck I bet I can fit a polynomial to the data and predict everybody “MAY” be deceased in 23 years (or 27 years if I add just one more order to the “magic” polynomial).
Be very careful with that “curve fitting” magic, it is very easy to convince yourself that you “know” the future……
Cheers, KevinK.
Kevin,
You said, “Sure, it could all work out exactly as you predict, or it could all go in a totally different direction….” Extrapolations are always at risk of being wrong I would say that as a rule of thumb, if one is using a polynomial fit to extrapolate, the risk is greater as the order is increased. On the other hand, fitting a linear trend to what is obviously a curvilinear relationship guarantees the extrapolation will be wrong. The question is, how wrong? Is it useful for what one is trying to do?
Kevin,
You said, “Sure, it could all work out exactly as you predict, or it could all go in a totally different direction….”
Extrapolations are always risky because of unpredictable changes in other influences. However, I would say that a general Rule of Thumb is that the higher the order of a polynomial fit, the greater the risk of being wrong. On the other hand, fitting a linear trend to what is obviously a curvilinear relationship is bound to give an incorrect extrapolation. The question is, how wrong? Is it good enough for government work?
This is what caused both population (of any animal make or model) and CO2 to rise. Now we just need to figure out what “this” is. Why? We might want to keep whatever “this” is around. Without it lots of us will end up just like this hairy dude. Frozen in ice.
https://nas-sites.org/americasclimatechoices/more-resources-on-climate-change/climate-change-lines-of-evidence-booklet/evidence-impacts-and-choices-figure-gallery/figure-14/
This issue was covered elsewhere a few years back, and I cant remember the exact place, but the key point is that there is an intermediate graph to be drawn, and that is per capita energy use versus population density. i.e hunter gatherers at uber low density use very little per capita energy – they eat and they wander.
But the modern metrosexual Green living in an air-conditioned city has a carbon footprint that is far far higher due to use of fossil energy to grow his fertilised beansprouts, manufacture his eco bicycle, pump his uber regulated water and process all his shit….
Joking apart, the point is that whilst nature at low energy input can manage to clean water, grow food and process manure, at high population density natural processes can no longer cope. European populations recovered extremely slowly after the Black Death over a period ofcenturies until (mainly agricultural initially) advances allowed a rapid population growth in the 18th 19th and 20th centuries. London became almost uninhabitable in the 19th century due to the massive volume of shit it produced, and required a massive sewerage project and steam pumps to solve it. Until the development of the steam railway the ability to actually transport food into the city was also limited. The US railroad is likewise associated with the development of high density cities.
I am surprised the author here was not aware of this study. I seem to recall that per capita energy is correlated extremely closely with population density across the world as it is today, and of course a rising total world population must at least be absolutely correlated with average population density in a finite sized planet…
I have a personal opinion, unsupported by data, that the modern western city is in fact a massive energy sink, that produces nothing of any value at all, all the manufacturing having gone to china, and in fact if e.g. London were wiped out in a nuclear blast, the rest of Britain would benefit enormously. And to plagiarise the great Billy Connolly , it wouldn’t look substantially different afterwards anyway.
Every breath we humans take increases the CO2 in that lung full from 400ppm to 40,000ppm. It’s patently obvious why there is correlation between population growth an CO2.
Advances in civilization, technology, medicine and standard-of-living in general all add to total CO2 production, but also reduce death rates for children, injured and sick, therefore increasing population.
Perhaps a global average SoL (Standard-of-Living) factor should be applied to the population numbers?
Option 5: There are other influences on the levels of both population and carbon dioxide left out by this perspective that would be obvious if plotting population v CO2 for the last million years. But I agree that short-term we expect both pop and CO2 to rise. Temp and sea level less so.
Let me get this straight; the time period, 2006 to 2015, is really short for a statistical analysis. Anthropic CO2 is less than 5% of the total CO2 increase, so, unless all other CO2 increase is abnormally held constant, how are we even able to even see the anthropic CO2 fraction? How is this a valid analysis? I vote for option 1. You could just as easily plot CO2 vs. GDP per person or the price of tea in china. Correlation does not imply cause and effect. Everyone drinks water and everyone dies, but drinking water does not cause death.
I have energy and world population data going back to 1800.
There is a rough correlation between fossil fuel consumption and population growth, largely because human economic activity requires energy. Although the energy consumed per unit of GDP is either modest or declining within developed economies, it has accelerated in emerging economies in the Middle East and the Western Pacific (among others). I have the data to graph if anyone is interested.
I’ve got a horrible doubt about this analysis. if taken literally it would seem to imply that if the population stopped growing then so would the CO2 ppm. That seems a very unlikely outcome. The reason this analysis is flawed is that it is plotting tw trends that are strongly corrleated to other trends (per capita GDP for instance) which are far more important.