Tuesday, November 1, 2011

Seven Billion: The Graph

According to the UN, yesterday the planetary human population crossed the seven billion mark.  The New York Times notes that there's some carping among the demographers as to the exact date but it hardly matters.  There's a six month or so window of uncertainty, but we might as well pick a date to do a little collective reflection on the meaning of seven billion, and now will serve quite well.

The above shows estimates of global population from the time of Christ on: data are from the UN after 1950 and via Brad deLong before that.  I like to look at it on this longer timescale as it makes it clear what an extraordinary event we are living through.  The steepness of the wall in the second half of the twentieth century shows it graphically.  Since I was born in 1965 the global population has more than doubled, and it could easily add as many people again before I die.  It's an extraordinary thing for a population to have a doubling time markedly less than the lifetime of an individual member.  Throughout the pre-industrial era the doubling time was many times longer than that, and indeed the population frequently shrank (for example, in the Dark Ages, and following the Black Death).

As to how it ends: who knows?  Here is the range of official scenarios from the UN:


Burk said...

To me, the question is- has this been entirely a transmutation of fossil fuel into human biomass?

Or have we reaped technological (i.e. durable) benefits along the way that can allow the party to continue after the booze runs out?

Nick G said...


I think the next interesting chart would be the first derivative: the rate of change.

I think you would find it encouraging: IIRC, we would see a clear peak several decades ago, and a pretty sharp decline since.

The next interesting chart would be of fertility rates, which precede changes in the overall population level, and then you might want to look at death rates. Fertility and death rates ultimately determine the behavior of population growth.

After that, if you still had energy for deeper analysis, you might want to differentiate between OECD and developing countries, distinguishing between Asia and Africa in particular.

Nick G said...


Here are someone's comments (I lost my source link), which seem not unreasonable:

"This chart from the UN's department of economic and social affairs shows the problem quite clearly.

The problem is all in Africa. A projection of 2.5 billion more people in what are already the poorest countries. The makings of a catastrophe, the like of which has never been seen.

And that's the "medium" scenario, in which population peaks late this century. Have a look at the high fertility scenario in figure 1 of that series. That's the track we're currently on.

Africa is big and empty (by the standards of Asia, Europe and the Americas). But it's also dry and getting drier, and most of its soils are degraded.

There are two ways this can go.

We can have a miraculous outbreak of neighbourly concern among the rich and middle-income countries, along with sudden unprecedented concern of Africa's governing elites for their own people. This seems about as probable as my winning Lotto.

Or the death rate will rise, and rise..."

Robert said...

When I was a small child my parents purchased a children's encyclopedia, The Book of Knowledge. I was impressed by a chapter heading that gave world population at 2 billion.

Stuart Staniford said...

Nick G:

You can see quite a bit of that kind of thing here:


though the graphs are a few years behind now.

noiseformind said...

Dear Stuart,

I read your blog every day but I rarely comment, sorry for that.

Being a consultant on construction for the petro-chemical industry I am really worried with this graph, it gives me the utter creeps.

My main issue is the little publicized fact that for each calorie that we take to our mouths it can take something between 25 to 65 calories of burnt oil to produce, ship and storage it. I keep wondering if all this commotion in the world is nothing but an attempt to deviate us from the notion that in 2013 China wont be able to feed one third of their population properly and most of the rich countries wont be able to supply themselves properly with natural resources, mostly coal, oil and generic metals.

Just look to ammonia production. It is extremely important that ammonia is fed into the agricultural cycles through fertilizers but India and China are diverting ammonia main source in recent years, LPG, to energy production. So crops are less fertilized and the yield per acre gets lower and lower so you have this massive fertile soil destruction in both of this pivotal countries.

In my point of view, anybody in a non-nuclear, not self-sustained energetically, should not make any plans further than 2020 :)

But this is my view that might be flawed in many ways.

But insurance is leading the way. All contractors envolved in maintenance contracts in KSA and Abu Dhabi aiming further than 2020 are paying massive premiums compared to just one year less, 2019. I believe that if somebody as crunched the numbers and sees no point in assure anything beyond 2020, then probably we should start looking out.

Same thing for data center rents assurance over 2022 right now.

I looooooooooooooooove your blog...


Nick G said...

for each calorie that we take to our mouths it can take something between 25 to 65 calories of burnt oil to produce, ship and storage it.

I've seen a 9:1 ratio, with most of the calorie inputs not being oil. Refrigeration was the biggest component, most of it at the site of the consumer.

noiseformind said...

"However, transport energy consumption is also significant, and if included in these ratios would mean that the ratio would decrease further. For example, when iceberg lettuce is imported to the UK from the USA by plane, the energy ratio is only 0.00786. In other words 127 calories of energy (aviation fuel) are needed to transport 1 calorie of lettuce across the Atlantic. If the energy consumed during lettuce cultivation, packaging, refrigeration, distribution in the UK and shopping by car was included, the energy needed would be even higher. Similarly, 97 calories of transport energy are needed to import 1 calorie of asparagus by plane from Chile, and 66 units of energy are consumed when flying 1 unit of carrot energy from South Africa."

I hope this helps,


Nick G said...


Those examples are for food being flown between continents. That's a non-representative outlier.

I believe that transportation energy is included in the 9:1 ratio that is generally used.