The Ergosphere
Monday, October 05, 2009

Speculation on limits to growth

If I may offer a science-fictional scenario for techno-cornucopianism, the limit for earth-based society is when it becomes something like a living system which can reproduce its components from the local resources.  The elements of carbon, hydrogen, oxygen and nitrogen (CHON) are available just about everywhere in various proportions, and it is essentially impossible to run out of silicon, aluminum, magnesium, and many others because they form such a large fraction of the crust or dissolved oceanic solids.

Energy available to such a society is a substantial fraction of the sunlight reaching Earth's surface.  This is many times more than we use today, so even if a society based on such bio-mimic systems must plateau it will do it at a far higher level than the present.  The real issue is what happens if it becomes unstable.  That depends on how the designers choose to build the system.  A conventional industrial model can collapse from inter-dependency on parts, but if the bio-mimic systems are self-reproducing, the technological capability can sustain itself through a collapse of part of the system and rebuild afterward.  This is what we've seen with life for hundreds of millions of years.

I believe that our level of understanding will let us get to this state within the next century, perhaps the next 50 years.  All we have to do is keep going.  Right now our technological systems are in the state of auto-catalytic RNAs dependent on the supply of molecular building blocks from natural processes.  When we can synthesize anything we need from soil, air, water and sunlight, we will have broken through a great many resource limits.

We're going to have a contraction of oil supply henceforth, but if we can use electrified rail, battery vehicles and different living patterns to remove the need for that oil supply, we can still live well.  Replacing coal with nukes removes most of the impact of electricity on the environment.  Project Better Place has a plan for continuing something very close to BAU, though that's not a requirement to avoid a collapse.  What we need is the vision (like PBP) and the will to pursue it.  "If we don't change the direction we're going, we're likely to wind up where we're headed."

Agriculture looks like a serious limit. Sustaining twice today's population at twice the agriproduct demand per person looks feasible. Increases in yield, argrichar, biogas fertilizer, and other sustainable practice.

But much more than that? Hopefully it won't be necessary. It seems possible, but likely at the expense of ecosystems.

We use up something like a third of the land area for various types of agriculture. That's a lot. Expanding greatly will certainly mean cutting down forests and severely affecting ecosystems on a global scale.

To avoid that in a heavy growth scenario, you'd have to think of ocean farming, vertical farming and other exotic stuff, but when the $$$ comes into the equasion, things don't look so good, especially when you look at the large number of poor people on this planet. Unsustainably draining an aquifer is much cheaper than sustainable desalinated water, and will remain so in many places for decades to come. Poverty is a serious issue when considering limits to/impact of growth.

Hopefully, the majority of demographers are right and population will stabilize at less than twice today's level.
I'm not so sure we're that limited.  Since we're looking at rising sea levels anyway, consider aquaculture.  Algae is extremely productive, and feeding fish turns it into protein with fairly high efficiency.  Using species suited to brackish, sea or even saturated salt water could allow the available water supplies to be used whatever the salinity.

Doing this would require lots of effort to raise dikes and some to pump water, but people have done more (e.g. terraced rice paddies in Asia) and used RE (Dutch water pumps draining polders) with very primitive technology.  I think the real issue is going to be getting the systems (species mixes) selected, tested and accepted by the people who'd use them.
Aquaculture has massive potential. I don't see things as rosy as you. The problem is, its really tempting to just cut down some forest or burn grassland etc and convert to agricultural area, especially for the world's poor. With aquaculture, the investment required is serious, also in terms of time required, and requires expertise, and is not applicable to the livelihoods of communities far from the sea. The same is true for sustainable desalinated water; far from the sea, draining an aquifer is going to be too cheap to resist.

The most likely scenario may be that there will be a lot of aquaculture, but also a lot of ecosystem destruction (taking forest, grasslands etc) to make way for terrestrial agriculture.

Better hope for a stabilizing population, and eliminatioin of poverty.
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