Tuesday, May 3, 2011

Part 7 The relationship between global population and global petroleum production

Based on my analysis of regional petroleum production trends presented in part 2 and part 3, I was able to make some predictions in part 6 about peak oil and total recoverable oil (Q), for the seven regions studied: (Middle East, ME; Former Soviet Union, FS; Africa, AF; South America, SA; Asia-Pacific, AP; Europe, EU and North America, NA), as well as global (WO) production, peak oil and Q.

Here in part 7, I examine the correlation between global population and petroleum consumption and consider the merits of two possible scenarios for population change in light of declining petroleum production.  

I want to make clear at the outset that I am neither advocating for or against population control.  It doesn’t really matter what I think, and, nothing I do or say will influence the outcome.  I am just watching for trends and relationships, and considering different scenarios, in the hopes that this information might help people better understand and prepare for the hard times that I believe are ahead.

If you have an emotional reaction to this analysis, you might be the kind of person who wouldn’t want to know if they have six months (or six years) to live.  I would want to know, but I understand that some would rather not. If you would rather not, then you may want to exit now.


I think that the wedding of population growth and petroleum production likely occurred with the Green Revolution in the 1960s and 70s.  The Green Revolution was at least portrayed as being  about the laudable goal of helping people in undeveloped countries avoid starvation by transferring to them the modern food production technologies used in developed countries.  This technology transfer included the use of pesticides, advanced irrigation techniques, petroleum-based synthetic nitrogen fertilizers and new seed varieties (requiring higher inputs of petrochemical to be most effective).  While being very effective at increasing food production, these modern techniques are also heavily dependent on petrochemicals, and hence a continuing supply of petroleum and petroleum products. 

This is the reason why some have argued that the world is now essentially Eating Fossil Fuels.  Indeed, even US house representative Barlett has stated the same:

We started out with about a billion people and now we have about 7 billion people almost literally eating oil and gas because of the enormous amounts of energy that go into producing food. Almost half the energy that goes into producing a bushel of corn comes from the natural gas that we use to produce the nitrogen fertilizer.  Roscoe Barlett R-MD, HEARING BEFORE THE SUBCOMMITTEE ON ENERGY AND AIR QUALITY, DECEMBER 7, 2005, Serial No. 109-41. 

If the global food supply has become dependent upon the availability of fossil fuels, and, the supply of those fossil fuels is declining, then it is easy to see why the global food supply could be in jeopardy.

Taking this further, if sustaining the present global population is only made possible by the petroleum-dependent technologies of the Green Revolution, then what happens to food production, and population growth, when petroleum production goes into terminal decline?  

My analysis in Parts 5 and 6 suggests that global petroleum exports and production are in decline now, with exports likely to hit zero in the next 20-25 years.  Can food production continue to expand, or even remain constant if there isn’t enough petroleum to expand or even sustain the Green revolution?  If food production growth stalls out, how can the global population continue to grow?

Jay Hanson’s die-off scenario

Hanson said in a 2008 interview that he used the term “die-off” and created his web-site of the same name in the 1990s because he saw a horrible future ahead, with 90% of the earth’s population dying an untimely death.  Hanson also see the economies of the world going into decline as they will be constrained by declining net useful energy (i.e., the ERoEI goes down).  Hanson expects that resource wars will occur to stave off the decline in standard of living in certain regions. Unless people change their ways (i.e., consumption declines), Hanson sees the world’s population declining at about the same rate as the rate of decline in the resources. 

If the world’s food supply is now tightly linked to the petroleum-dependent techniques of the Green Revolution, then petroleum would be a key one of those declining resources.  Therefore under this scenario, we can hypothesize that population should decline as petroleum consumption, and hence the food-supply, declines.

Julian Cribb’s feed 9-11 billion scenario

Cribb suggests that the world is at risk of a global food shortage by the mid-century that will cause massive famine (see e.g., Jim Puplava interview and U of Melbourne seminar).  Cribb believes that the world needs a Green Revolution 2.0 in order to feed the world’s population, which is estimated to reach 9-11 billion by 2050-2060. 

Cribb believes that the economies of developing countries will continue to grow and therefore global food demand will need to double as this additional 5 billion people, mostly in developing countries like China and India, demand more and higher quality food (that is, food with a higher protein content). 

My impression is that Cribb sees the previous Green Revolution of the 1960-70s as being fueled more by knowledge and technology transfer and less so by the petroleum inputs that were required to actually implement that knowledge and technology.

However, Cribb sees the coming inability to grow the food supply as being mainly due to resource depletion on several levels.  Oil certainly is one factor, but there is also the growing scarcity of fresh water, farm land being encroached by urban sprawl, overused soils being depleted of nutrients, declining fish stock and climate change.  Much of the produced food is inefficiently wasted (1/3 and 1/2 in developed and developing countries, respectively, according to Cribb).   There is also the worry that the agriculture and transportation sectors will lose petroleum to military uses, and, that this will further reduce the ability to produce and deliver food efficiently.  Many of these factors are linked and feed back on each other, Cribb says.

Cribbs sees the huge challenge facing farms is how to double the food supply with less water, less land, less petroleum, less petrochemical based fertilizers and pesticides, and less money being invested in new technologies.  He calls for a “change in behaviour by every person on the planet, especially in rich and urban societies.”  He calls for more funding for agricultural research and education.  Ending the huge amounts of waste in the current food production system would help and specifically the development of technologies more suited to smaller farm such as found in the developing world.   Cribb would also like to see a change in the diet of Americans and other developed countries away from protein towards a higher vegetable content.  Perhaps higher food prices would help achieve these goals, Cribb suggests.

In the absence of this doubling in the food supply, like Hanson, Cribb see famine, resources wars, “tidal waves” of refugees, and the collapse of governments in many countries.

Population decline now, population decline later, or infinite population growth?

I use Hanson’s and Cribb’s presentations to highlight two different scenarios that could occur over the next 50 years. 

On one hand, there could be a strong decline in population, a die off, as Hanson puts it, or famine, as Cribb puts it, as the vital resources needed for food production decline.  As petroleum is one of those vital resources, then as petroleum production declines, so too should the population decline.  Presumable the end point would be a world population at about the same level as it was in the pre-petroleum age.

One the other hand, perhaps we get Cribb’s 2.0 Green Revolution, and the world’s food supply is somehow doubled, even in the face of declining resources, to support a world population of 9-11 billion by the middle of the century. 

Cribb didn’t talk in his Puplava interview or his proper U of M presentation about what happens after the world’s population reaches 9-11 billion at mid-century.  However, in the Q&A period following the U of M presentation (~51 min into the audio presentation) the question was raised about the “blind acceptance” that the world actually had the ‘carrying capacity” for a population of 11 billion people, and if this was even something good to strive for. 

In response, Cribb finessed his answer, by agreeing with the questioner that food and population are intimately linked, that population was an “elephant in the room,” but that the discussing population was “a dangerous place to go.”  He argued that we have to find a way to manage the population down to some sustainable level.  Cribb pointed out that the sustainable population level will depend on the diet that people have, and, he hoped that managing down the population will be driven by the growing movement of women deciding to have less children.    

It is my impression that Cribb is hoping that if we can just manage the coming population boom to the mid-century, then the birth rate will naturally go down, and the population problem will go away on its own accord.

I think that Cribb’s hoped for Green Revolution 2.0 simply tries postpones the inevitable population decline—possibly with an even larger die off in the later half of the century—but perhaps without the resource wars. 

And if the world’s population were to continue to increase after mid-century, then what?   “Green Revolution 3.0” to support a world population of 15 billion by the end of the century, and so on, ad infinitum?   If you accept that we live on a finite planet with finite material resources and finite energy, then I think the notion infinite population growth can be rejected outright. 

What is less clear, however, is what the world’s population carrying capacity actually is, in view of declining resources, including declining petroleum. 

I wanted to see if the past annual data on population and petroleum production could put some numbers to two scenarios roughly matching Hanson's and Cribb's scenarios: population decline starting now, or,  continuation population growth (likely followed by a decline later on).

My continued population growth scenario

 Figure 25 shows (right axis) the cumulative population data for the seven regions that I have studied in previous parts of this series.  The data includes the US Census Bureau International Database of population statistics from 1950 to present (open black circles) as well as the Census bureau’s population projection to 2050 (solid black line). 

Also shown in Figure 25 (left axis) is the reported per capita global petroleum consumption rate (barrels per person year, b/py, open red circles), which I calculated from the per capita consumption rates for the seven regions, presented in Part 5 (Figure 18).  The data is from the BP Statistical Review, which reports back to 1965.  To this, I added per capita consumption rates from 1950-1964, which I obtained from another source.  I used global petroleum production rates reported for this period reported by the Earth Policy Institute, plus, the US census bureau’s reported population data to calculate per capita global consumption for the 1950-1964 time range.  

The predicted global per capita consumption from 2010-2050 (solid red line) is based on the composite of my predicted petroleum consumption rate trends for these seven regions from Part 6 (blue curve in Figure 20), divided by the US census bureau’s population projection. 

Figure 25 illustrates that the 4.2 billion increase in population occurring over the past sixty years (2.6 billion in 1950 to 6.8 billion in 2010) has occurred in the presence of expanding per capita petroleum consumption, peaking at 5.3 b/py in 1979, falling back to 4.3 b/py in 1983 and remaining in a narrow range since then.

If the US census bureau’s prediction of global population increase, and, my prediction of petroleum production rate decrease are both correct, then we should see a dramatic decline in per capita petroleum consumption over the next 40 years from 4.2 b/py in 2010, to only 0.5 b/py in 2050.

Not withstanding the other important factors affecting food production (water, soil, waste etc...) I think that this is roughly what would have to happen if Cribb’s scenario would come to pass.

My population decline now scenario

Figure 26 shows the relationship between global population and global petroleum production from 1950 to 2009.  There is a pretty strong linear correlation (solid blue line) between population and petroleum production.

It is bit harder to see, but there are also linear sub-trends within this data.

Figure 27 shows the same data as in Figure 26, except that I have added a line connecting the data points for adjacent years, and, I performed linear regression analysis for two different periods: 1950-1979 and 1982-2009.   

Table 13 summarizes the linear regression best fit slope, intercept and correlation coefficient.

Table 13: linear correlations between global population and petroleum production rate
Slope (b / bbs per yr)
Intercept (b)

Although correlation does not prove causation, what would these linear relationships imply if we assumed that increasing petroleum production (my assumed proxy for food production) was the cause of the population increase?  This does not appear to be too outrageous an assumption, given the suggestion that the petroleum-driven Green Revolution is what has expanded the global food supply and hence increase the carrying capacity of the earth, if only for a brief period until the oil runs out. 

Remember, this is just an assumed causal relationship made on my part, so that I can work some numbers up for this scenario.

From 1950-1979, the slope of 0.0816 billion people / billion barrels per year (b / bbs per yr), suggests that for every 1 bbs/yr increase in the petroleum production rate, the population increased by 82 million people.  But from 1982-2009, the slope of 0.215 b / bbs per yr suggests that the population increased by 215 million people for every 1 bbs/yr increase in production.   Why?  I speculate that this 2.6 times increase in the slope for the 1982-2009 time span, compared to 1950-79 time span, might be showing an increase in the efficiency of food production, perhaps due to a world-wide petroleum-driven Green Revolution. 

For the purposes of this scenario, I have assumed that the linear relationship for the 1982-2009 time span represents the world’s current dependence on petroleum production for population growth.  I will go a but further and assume that as petroleum production declines, as I predicted in part 6, the same linear relationship holds—but in reverse.  That is, for every 1 bbs per yr decline in the petroleum production rate, the population declines by 215 million.   Specifically, I used the slope and intercept for the 1982-2009 time span, presented in Table 13, to calculate the population as the predicted petroleum production rate declines from 2010 on. 

Figure 28 shows the result of this calculation, presented in a form analogous to Figure 25. 

The right axis shows the predicted steady population decline from 2010 to 2050 (solid black line)—a whooping decline of 5.5 billion people!   Of course a population decline mitigates the decline in per capita petroleum consumption (solid red line; left axis).  For instance, instead of per capita consumption declining to only 0.5 b/py in 2050 (Figure 25), in this scenario, per capita consumption is still 3.4 b/py by 2050—only about 20% lower than per capita consumption of 4.2 b/py in 2009.

I think that this is roughly what would happen if Hanson’s scenario to came to pass. 


For the continued population growth scenario represented by Figures 25 we are looking at a world population of 9.2 billion by 2050—an about 2.4 billion person increase over US census bureau estimates of 6.8 billion in 2010.  Can the estimate per capita petroleum consumption of 0.5 barrels per person per year by 2050 really by expected to sustain that level of population? I find this very hard to imagine.
For my population decline now scenario, the decline really would have to be quite severe just to keep per capita consumption at 3.4 b/py by 2050.  Only 1.5 billion people by 2050 means shedding 5.5 billion people over the next 40 years, or about 137 million people per year.  One hundred and thirty seven thousand people per year is many, many, untimely deaths.  That’s way more than the total number of military and civilian deaths in  WWI and WWII combined every year for 40 years in a row.  I also find this very hard to imagine. 

Is there anything from past relationships between population and petroleum consumption that gives some insight into which of these two scenarios is more likely?  I think there is, particularly in the regional data.

Join me next time when I will present my arguments as to which of these two scenarios I think is the more likely one to occur. 


  1. Houston, we have a problem..

  2. How interesting to be able to witness the end of an unprecidented era of blissful ignorance and be old enough to not have to live through the horror that follows. We live in interesting times.

  3. Ah yes, the ancient Chinese curse. But unless you only have a few years to live, I think that you will at least see some of it. We all live in "interesting times."

  4. More than any other time in history, mankind faces a crossroads. One path leads to despair and utter hopelessness. The other, to total extinction. Let us pray we have the wisdom to choose correctly. ~ Woody Allen

  5. I love it! Maybe we should combine the two: depair and utter hopelessness followed by total extinction? As Yogi Berra said, "the future ain't what it used to be."

  6. Global food (grain) supply peaked out in 2004. Population cannot grow with a declining food supply. Ecology 101

  7. Lishui,

    I think that you would have to acknowledge that even if there is a peak in the production of one important food stock, this doesn’t necessarily mean that population can’t go up, as it has over the past 6 years.

    For instance, according to the US census bureau statistics, the world’s population increased by about 450 million since 2004—the peak in grain production, by your account. That’s about the population of North America, in 6 years. Reality 101.

    I acknowledge, however, that other factors may temper the population rise, but, that's outside of the scope of what I was trying to look at here, which is, as indicated by the article title, the relationship between population and petroleum production, if any.

  8. There are two examples that come to mind where declining access to oil precipitated population decline with associated reduced access to adequate medical care and reduced food. North Korea when the USSR fell and Russia post USSR. Cuba also suffered and despite all the happy talk about Cuba, food is still short for the average Cuban. This information is from my Uncle who travels to cuba frequently.

  9. Thanks nathan,

    As shown in Part 8, the Former Soviet Union, which is dominated by Russia, population and consumption wise, did not decline in population by too much even in the face of a +50% decline in consumption.

    You will see Cuba featured in Part 9.

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