Liebig’s Red Line

I often see articles with inter-generational time spans and predictions that make no sense. The idea of nearly ten billion of us living on this little rock come 2050 is based on linear predictions of things that are already becoming non-linear. See Functional Triage for more thinking on this.

Our society has bumped into Liebig’s Law of the Minimum twice in the last two hundred years, as I first described in Dead Gods Of Atacama eight years ago. These two collisions in which we hit the upper limit of the least common basic plant nutrient, biologically available nitrogen, were resolved by first finding a fossil source, and then later by developing a process that trades fossil fuel for ammonia and follow on compounds.

Biological Liebig minimums put a cap on our population size. If we keep making biologically available nitrogen using fossil fuel, which currently contributes 1.5% of our total carbon dioxide, as well as a poorly characterized share of very potent nitrogen based greenhouse gases, we’ll find the limits are more to do with water and growing degree days. Corn wants moist soil and 86F days. Productivity declines when it’s hotter and all but ceases around 100F. This has grim implications for sub-Saharan Africa.


While originally developed in the context of biological systems, Liebig’s Law applies to technical systems as well. The same hopeful view on population also appears in connection with America’s automobile habit. “We’ll just be driving electrical cars.” This statement supports a future most Americans can visualize, but it’s not accurate. There simply isn’t enough lead, lithium, or other battery components to support a straight across switch, even if we could make the needed electricity.

This article on explains without descending into breathless warnings. There is a bound on our clean energy future thanks to the availability of key minerals. Even if we accept that we’re not all going to drive Tesla sedans, the constraints are tighter than that.

Research team warns of mineral supply constraints as demand increases for green technologies .

The same may be true for technology metals that could become essential in green technologies—like neodymium, terbium or iridium. These minerals are only needed in small quantities, but they are indispensable to making the technology work, meaning that while the scale seems small, the value is immense.

And that is the very soul of a Liebig Minimum in a single paragraph.

What happened in Somalia, what is happening in Syria, what NATO triggered in Libya, what has just begun in Yemen, these are the new normal. Overpopulated, arid places will be the first to fail. Egypt erupted in 2011, both Iran and Saudi Arabia are ticking bombs. When these oil producers are unable to escape what engulfed their smaller neighbors, we may finally turn to the renewable energy path we ought to have taken at a variety of inflection points over the last fifty years.


When we finally, inevitably do make that course correction, we’re going to discover that there isn’t enough to go around. Our population overshoot, rising from one billion circa 1800 when we began working the Atacama’s fossil nitrate deposits, to the seven billion today, rides on the back of our temporary conquest of this biological minimum, but there are technical minima required to turn Trinidad’s natural gas into American corn and wheat.  Peak oilers liked to talk about “getting back to our solar maximum”. What that solar maximum looks like is going to be heavily modulated by how much of the sun’s energy we capture and in what form.

A purely biological capture system looks like the world circa 1800, while a mindful use of mineral resources might leave us with a 20th century standard of living. Nobody has modeled this, really, because it’s too complex, and because those with the power to change course lack the political will to even make a clear eyed examination of our prospects.

There are a spectrum of potential outcomes for the Anthropocene, ranging from relatively cold, isolated, culturally homogenous Japan as the last bastion of our developed culture, to a genetic bottleneck for our species that finally pinches out on Wrangel Island or some other Arctic redoubt. Even the best outcome is a hard future to swallow from the perspective of someone born at America’s peak and inspired by the hopeful techno cornucopia  of Star Trek seen against the backdrop of our first shuttle flights.

Abandoned Buran Shuttle

Abandoned Buran Shuttle


3 thoughts on “Liebig’s Red Line

  1. Pingback: Record Heat Sans El Niño | Neal Rauhauser

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