How overpopulated is the planet, really? [View all]

[GliderGuider]

Last edited Fri Mar 22, 2013, 01:00 PM - Edit history (1)

There has been a lot of skull-scratching over the last 10 years about what the level of sustainable human population might be over the long haul. Sometimes people wonder about “optimum” population levels, which is an obfuscatory, bullshit way of asking, “How much of our modern high-energy lifestyle can we hang onto as TSHTF?”

My recent work on Thermodynamic Footprints prompted me to go back and re-visit the question, from the view of global average population density.

There are about 20 million square miles (50 million km^2) of habitable land on the planet. The other 2/3 is covered by snow, mountains or deserts, or has little to no topsoil.

An average population density for a non-energy-assisted society of hunter-forager-gardeners is around 1 person per square kilometer, down to 1 person per square mile. That pegs the upper bound for a sustainable world population at 20 to 50 million people. Based on that number, our current population is at least 150 times too big to be sustainable. Put another way, we are now about 1500% into overshoot.

However, the story is even worse than that. Our use of technological energy gives each of us the average planetary impact of about 20 hunter-foragers (and the comparable number for the USA alone is about 1:60). This means that the world’s “thermodynamic equivalent population” is 20 times our actual numbers, or about 140 billion .

The implication is that if we wanted to keep on with the average level of per-capita consumption in today’s world, we would run into an overshoot situation at a global population of about 2.5 million people. By this measure our population is about 3,000 times too big and active for long-term sustainability. In other words, by this measure we are we are now 30,000% into overshoot.

Maintaining an average American lifestyle would permit a world population of only about 0.5 to 1 million people – clearly not enough to sustain a modern global civilization.

For the sake of comparison, it is estimated that the world population just after the dawn of agriculture was about 4 million, and in Year 1 was about 200 million.

I’m just sayin’ …