The Second Bronze Age

Photo by Igor Dernovoy on Unsplash

The first bronze age lasted two thousand years and ended some three millennia ago. The second will begin — and eventually end — in a fraction of that time.

Will a global civilizational revival follow?

If you’d hoped that technological progress can only go forwards and upwards, eventually taking us into the stars and beyond, I have to disappoint you. Looking at our material, energy and biophysical realities, instead of eternal progress, we face a massive and permanent contraction. The depletion of easy to get oil (and an ever increasing energy cost of making diesel fuel as a consequence) will eventually put an end to all mining and manufacturing activities, and lead to a multi-decade-long cascading collapse. Environmental factors permitting, though, there is a chance (albeit a very thin one) for human civilization to resurge.

The coming collapse of industrial civilization won’t be your grandpa’s collapse. Be it a slow catabolic one or a rapid cascading collapse, it will leave behind a drastically degraded landscape, compared to the disappearance of previous civilizations. Societies who prospered and went missing prior to the industrial revolution were solely powered by renewable energy. And while most people associate renewable sources with the sun and the wind, the vast majority of energy powering ancient civilizations was obtained in the form of carbohydrates. People cultivating grain crops and pasturing their oxen used plants to convert sunshine, water, CO2 and soil nutrients into calorie-rich food for themselves and their draft animals. And while overgrazing, soil degradation, the depletion of nutrients, salination from irrigation etc. was always an issue, the collapse of agrarian civilizations gave at least a chance for the land to be regenerated (somewhat). Thus, after a dark age lasting for a few centuries, a new civilization would start it all over again. Of course, the compounding effects of these multiple iterations of agriculture have eventually destroyed the land, forcing follow up civilizations to expand their territories and to form empires to make up for the loss of soil fertility. The discovery of fossil hydrocarbons, on the other hand, has not only turbocharged this degradation process, but also replaced both human and natural productivity with a one time fossil resource.

You see, every civilization is unsustainable, but some are even more unsustainable than others. 

Using diesel powered machinery to dig up the land, cut down forests, blow up and carry away entire mountainsides was a “great” way to obtain all the food, wood, minerals plus coal oil and gas we needed. Once we run out of fuel though, we will not only have burned the easy to get part of a one-time energy resource, but destroyed, eroded and polluted much of the land as well. (For this reason it really doesn’t matter if there is an energy transition or not, it is our civilizational practices which are destroying the planet; not fossil fuels in and of themselves.) Our everyday actions are actively degrading the land’s capacity to grow plants and food for humans and animals alike. This not only reduces biodiversity and the carrying capacity of the land, but the amount of renewable energy which could be harvested in the form of wood and crops, too. And if this fossil fuel bonanza is over sooner and faster than our population numbers could adjust to naturally, then hungry humans will ravage the landscape in search for food — as well as for fuel to cook and stay warm — leaving even less nature for future generations. The future, lacking fossil fuels and an adequate biological productive capacity, will thus be rather energy poor.

Wasteland. Photo by Valentin Salja on Unsplash

Only after understanding our present ecological predicament can we see the dilemma of our 22nd century descendants. The year is 2124 AD, one century from now. The land in previously densely populated areas is now largely devoid of trees, the soil has been eroded or lacks nutrients and life. Radioactive fallout from burning fuel ponds, together with leaking oil and gas wells, have rendered large swathes of land totally uninhabitable. The climate is much hotter and sea levels are much higher — making much of coastal and low lying agricultural lands unusable. Animals larger than a rabbit are now also largely extinct: humans either ate them, or they perished due to a lack of food, heat waves and novel entities (endocrine disrupting chemicals, new pests and diseases etc.). 

Life in the Anthropocene, marked by the onset of climate change and a mass extinction event, is extremely difficult. While much of the land was destroyed as a result of what we could call a classic example of ecological overshoot and collapse, small groups of humans still struggle to survive. Located in a narrow habitable belt between the North Pole and the expanding deserts to the south, as well as in the southernmost tip of South America and in Tasmania, survivors of industrial civilization are now living in small villages. They’ve settled around some still viable farmland and — if the fluctuations in climate and local weather allows — grow some food and roam the land in search for edible plants and “firewood” from shrubs, or checking their traps for an occasional hare. Surviving members of the Homo sapiens species literally hang on by their fingernails. 

At this point we cannot rule out a complete ecological collapse bringing down the last human, either. Much depends on how fast this civilization goes down, how much nature is preserved in the process, and how bad climate change will turn out to be. The living world has a remarkable capacity to regenerate, though. Over the centuries forests will begin to regrow, grasses will cover the land and biological productivity will return. Not to its prehistoric level — we would need to wait millions of years to see that — but to a level where survivors of the human race (if there are any) could start to build cities again… (An unsustainable practice, I know, but that’s what we are, an unsustainable species.) As long as Earth’s climate allows we will continue with farming, as hunting and gathering will not be a viable option for large numbers of humans to survive. A lot of “ifs”, but presuming there is a chance for a resurgence of civilization, the question poses itself: how will that look like? What technologies will they use? From what material will they make their tools from? Will they have use of the vast amount of iron locked up in bridges, railways and buildings? Or, perhaps, will they return to an even older technology, such as making bronze?

Rusting bridge. Photo by Aditya Vyas on Unsplash

The reddish-yellow metal — after which an entire historical period lasting from 3300 to 1200 BC was named — has came to be the first widely used metal alloy in history. Made from copper and tin, bronze was hard enough to cut wood, flesh and bone, while requiring only a modest kiln to melt and work with. And while iron was already known in ancient times, it offered very little benefits over bronze: it was either too soft, or too brittle (depending on the carbon content) and has developed rust pretty fast. 

Most importantly, though, obtaining it required much more energy than making the copper alloy widely used during that age. The reason is simple: bronze has a much lower melting point (slightly below 1000°C or 1900°F) compared to iron (1538 °C or 2800°F). In practice this meant that that smelting iron required at least two times the charcoal compared to copper… And remember, we are talking about agrarian societies, where everything apart from a wind or water mill was powered by muscle work. Now consider the human labor (and ultimately energy) involved in cutting down two times as much wood, requiring two times the labor and two times the food calories — not to mention the fact, that such a practice would deplete forests two times as fast. (Ever wondered why people in medieval Europe have started to burn coal in large quantities in the run-up to the industrial age…?) 

Energy was the economy, even before we knew what it was.

Working with bronze also required much less human work, as such tools could be cast into their final shape, and then cold forged to obtain optimum strength. Compare this to working with iron ingots, which had to be hot forged requiring yet another pile of charcoal and a ton of hard muscle work (again, those food calories and wood which had to be obtained)… And as to the end result: just take a look at this video demonstrating how strong bronze tools can be, or this study proving that bronze swords has indeed seen heavy use in battle. 

Contrary to common wisdom, bronze was a surprisingly useful material. Even if you had to sharpen them somewhat more frequently, such tools were a much better proposition from an energy economics perspective than iron. As long as tin and copper mines were able to produce enough ores to satisfy demand, iron could not compete. (In fact one of the many reasons behind the polycrisis hitting Mediterranean bronze age civilizations around 1200 BCE was a lack of tin, which was hard to find and came from only one mine in present day Afghanistan.)

Despite what the myth of progress suggests, iron was not “chosen” over bronze. It was reverted to as mines producing tin depleted.

Now, back to the future, into the 22nd century. All easy to mine, high (metallurgical) grade coal is now long gone. Forests have started to recover, but thanks to wildfires, a rapidly changing climate, soil erosion and the general collapse of many ecosystems, large, previously wooded areas are still covered with nothing but grass and some hardy bushes. In other words: energy from wood remains scarce, even as fossil fuel production has been reduced to zero. 

Metals left behind by industrial civilization, on the other hand, are all over the place. Although bridges and buildings from the industrial era have all collapsed and railroad tracks have largely turned into rust, one does not need to travel far to obtain some high quality scraps. Copper, which develops a greenish layer of patina protecting it from further corrosion, for example, can be still located in abandoned power stations and scrapyards in the form of windings found in electric motors and large transformers. And while tin has (again) become very scarce, aluminum still remains abundant. (Just like copper it also develops a layer of protective oxides on its surface and is also widely available.) Given the fact that tin can be easily substituted with aluminum when making bronze, why bother picking up rusty railroad tracks, and cut down entire forests to turn them into charcoal then, when one can make aluminum bronze at a fraction of the energy invested (wasted)…? Presuming that at least some basic metallurgical skills survive the coming dark age, a second bronze age is upon us.

Recycling the past, though, can only go to a certain extent. The “problem” is that every recycling process, no matter how careful, is wasteful to a certain extent: 5–10% of the material will always be lost in each and every round. With mining gone, however, there will be no way to make up for these losses. Once all former cities and industrial centers will be stripped of their valuable resources, and all what remains will have turned into dust, people a couple more centuries later will have nothing left to recycle… Other than their own tools. 

The industrial age has saw the strip-mining of the entire planet in search for resources, leaving nothing for future generations.

As we have seen in the case of the first bronze age, humanity has always went for the lowest cost resources first; requiring the least amount of energy and work to get. Higher grade ores, containing valuable metals in the double-digit range (with rock to metal ratios reaching sometimes as much as 20%), were thus already harvested in ancient times. Soon enough ore grades fell below a point where the labor and energy invested was not justified by the meager output of these mines. Thus the only way to circumvent this problem — before the industrial revolution — was to conquer other nations who still had some viable resources. It was only during the industrial age, when thanks to an incredibly dense and abundant energy source, oil, humans have been able to mine resources previously deemed uneconomic (low grade ores with 1–2% metal content). 

In the absence of fossil fuels, and especially oil, however, our descendants will no longer have that luxury. They will inherit a world where all the high grade ores (amenable to artisan mining and smelting technologies) will be long gone, and working with the remaining low grade ores would require prodigious amounts of labor and energy from wood and grains. Just for fun take a look at this guy trying to work with a 1% grade tin ore, while still using a lot of modern tools and electricity. Jokes aside, listen to the old miner in the linked video explaining the process of depletion, and how ancient folks went after thin seams of ore — only to abandon the entire project once it became too labor (or rather: energy) intensive to continue.

Photo by Douglas Lima on Unsplash

Having run out of materials to recycle and ores to mine, the second bronze age, too, will thus come to an end. Once again people will have to revert to using ‘bog iron’ and ‘iron sands’ from swamps and rivers; the only two somewhat renewable sources of metals. As we have seen above, though, working with iron will still require a large amount of energy (a lot of wood harvested and turned into charcoal). Metal objects will thus be made on a very low scale, again. Life in Edo Japan is a case in point: since the islands lacked minerals, metallurgy was restricted to making a few high quality and expensive tools and swords. Wooden buildings were held together by clever joints and wooden bolts — no iron nails were used. Something similar, combined with regenerative agriculture could be sustained for several millennia to come — unlike a fossil fuel and minerals based industrial society. Since civilization, agriculture and resource extraction is by definition unsustainable on the long run, especially in an era past the stability of the Holocene, even the gentlest societies will begin to disappear. Thus, as the compounding bad effects of erosion, nutrient depletion, climate change and the sixth mass extinction continues to pile up, the largest remaining mammalian species on the planet and the last of the Hominid genus will eventually join the ranks of giant sloths, saber tooth cats and the woolly mammoth.

Until next time,

B

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