Thursday, January 28, 2010

Human Consumption Then and Now

The first post here tells you what I am trying to understand and record in this blog.

The current post is the first of probably a very large number of short essays and pictures about our human demands, and the growth of those demands, on world resources.



The two consumption charts here are worth a thousand words.  (Click for larger charts). Each point represents one year of total human consumption, measured in money, at the end of that period.  Compared with our annual total consumption today, our annual consumption in previous millenia, and even as recently as the 18th century, was vanishingly small.  The detailed numbers (too small for the charts at this scale) say that our consumption in the year 1800AD,  was less than one half of one percent of our consumption in the year 2000AD -- 200 years later.  In 2000 we consumed between 300 and 400 times more of natures "stuff" than we consumed in 1800.

I have used GDP measured in "International Dollars" to compare consumption over millenia and centuries.  The data come from a variety of economic historians, mostly from Professor Brad de Long of Berkeley.


These two charts tell us that in the year 2000, we humans consumed about $40 Trillion worth of nature's resources, and that our consumption (at this scale) apparently began rising in the 20th century.  For reference, the current (2008) US GDP is approximately $14 Trillion current US dollars, and world GDP is about $60 Trillion current US dollars.

The history laid out in these pictures tells us that the amount we consume, and the rate at which we increase our consumption is uniqe.  Never in all the history of our species have we come even close to today's consumption, or the rate at which we are increasing our consumption.

Our economic theories are rooted in the work of Smith, Say, Ricardo and other late 18th century philosophers.  None of these western Europeans were in the least concerned with "growth" issues.  Growth in their day was slow, life was miserable, science was just emerging, and their fellow citizens had recently opened up the "New World" with its limitless resources.  Improving the standard of living for their fellow citizens as fast as possible was the overarching goal for these savants.  The lone voice (Malthus) preaching limits was soon shown to be wrong, as western man improved his standard of living by leaps and bounds. .

It is not surprising that contemporary concerns about "running out of resources" surfaced only in the late 1900's.  There are a few scientists around now who are predicting trouble as soon as two decades into the future, and a few more who are pretty sure we cannot continue growing much beyond 2050.  But there have always been prophets of doom around.  Cassandras are nothing new.  And there are virtually no economists who are willing to forsake the mantra of limitless growth.

Let's try to weigh the probabilities:  Is the current rate of growth in our consumption likely to continue?  Or are we beginning to hit natural resource limits which will reduce our growth rate?  Or worse still, stall our growth rate?  As we think our way through the macroeconomic and societal consequences of these answers, we will keep an eye on the career opportunities the inevitable changes will present.

We live in interesting times.

Let's start our quest by digging into the consumption numbers.  Did we increase our population, or our average consumption per person, or both?


Here are the pictures:  Clearly something uniqe in our history started to show up in population numbers in the 18th century, and in average consumption in the 19th century.  Whatever the cause, the combination of population growth and average individual consumption growth caused our consumption to skyrocket in the 20th century.  We entered the 21st century with a global GDP of about $40 Trillion, a population of just over 6 billion people, with an average income of about $6500 per person.


I will end this post with a picture quantifying our rate of growth.

The large chart below is based on data we have already seen.  It shows the percentage increase in annual consumption and population, every century, during the last millenium.  Note particularly the massive increase during the 20th century.  Average annual income increased by  nearly 1000% (10x), compared with a population increase of only about 300% (3x).   The combination of these two factors led to an explosion of 4000% (40x) in total annual consumption during the 20th century.

Do we think we can keep this rate of growth up for the next century?  The next half century?  The next quarter century?  And if we decide it is unlikely, what do we do about it, if anything?  And if we do nothing and continue with "Business as Usual" what are the risks?



PS  For you historians and economists: in the chart below I have selected data just through the 18th century for your interest.
When you look at the 11th 12th 13th and 14th centuries, and focus on the growth of population and income, you will see an inverse relationship.  As the population growth rate increases, the GDP/capita growth rate falls.  In the 14th century population actually declines due to the plague early in the century, and by the end of the century individual income soars due to the scarcity of labor.   It is not until the 19th and 20th centuries that both population and individual income grow together, and  GDP/cap grows nearly three times faster than the population.  Why?  Because machine assisted production increases human productivity.  Fossil fuel energy has begun to replace human and animal energy



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