After a collapse will people grow their own food or plunder others?

[ In this post Ugo Bardi looks at what will happen if society collapses and we have to suddenly go back to pre-industrial agriculture conditions.  A back to the land movement where people grow their own food may not happen. More likely, nomadic groups will plunder the countryside — that’s what happened when Rome fell. 

I associate Ugo Bardi with the concept of Seneca Effect, but he did not write this and I can’t figure out who did.

Alice Friedemann  author of “When Trucks Stop Running: Energy and the Future of Transportation, 2015, Springer]

Author unknown. March 3, 2016. The Neopaleolithic: Hunter-Gatherers of the 21st century.

The Seneca Effect: Decline is faster than growth.

There’s a common perception that as our society reaches a peak to the degree of complexity it can sustain, we will gradually return to a lower level of complexity that preceded it.  However, for us to be able to return to a lower level of complexity typically requires us to have maintained the technologies that enabled the previous level of complexity, as well as relevant knowledge of the skills we utilized to sustain the previous level of complexity.

Population.  One major problem we face is that most people simply don’t live in places where food is grown to feed them. Saudi Arabia imports 80% of its food, Kuwait 91%, Qatar 97%. Japan’s caloric self-sufficiency is estimated at 39%. It’s simply not possible, without mass migration across continents, for people to live in those places where their food is produced and participate in food production. This would require mass migration to Australia, New Zealand, Canada and Russia.

Urbanization.  An estimated 49% of people lived in cities in 2005, up from 13% in 1900. This figure continues to rise. It’s questionable whether people are better off in cities or outside of them. It might seem self-evident that the countryside would be preferable, but it’s likely that critical infrastructure in cities can be sustained longer than it can be in more rural places.
Economic decline so far seems to lead to a rise in urbanization, rather than the opposite, as rural places become increasingly expensive to inhabit. What causes urbanization is a reduction in dependence on physical labor in agriculture. So far there seems to be no reversal in this trend.

The Dutch Method: Greenhouses

The Dutch method of food production is characterized by its complete unsustainability. The Netherlands produces 17% of its own need for grains, but a massive 241% of its own need for vegetables. Incredibly, this country produces 290% of its own need for tomatoes, a tropical crop native to central America, where it grows as a perennial. The vast majority of this (80+%) is exported to other countries

How is all of this achieved? Through the use of greenhouses. In the Netherlands yield per hectare of greenhouses lies almost ten times higher than in similar greenhouses in Spain, allowing this country to be a world-leading food producer, despite its lack of farmland.

Various unsustainable technological methods are used in this process.

Rest-heat and captured CO2 from fossil fuel based power plants is routed to the greenhouses, to keep tropical crops like the tomato at the temperature needed for optimal growth. At least 90% of greenhouses are artificially heated.  Other greenhouses burn their own fuel, raising temperatures and creating an environment of elevated carbon dioxide in the greenhouse, typically of 1000 parts per million, to further stimulate growth beyond what heat alone can accomplish. An estimated 7% of natural gas use in the Netherlands is used directly by greenhouses to deliver carbon and heat to plants. A fuel crisis, whether through logistical problems or fossil fuel depletion, thus inevitably also means a food crisis.

Other nations are heavily dependent on greenhouses too, though few of these greenhouses are as completely dependent on modern technology as the Dutch ones. Globally, 473,466 hectares of greenhouses are used, out of which slightly more than 10,000 hectare is found in the Netherlands. A stagnation in greenhouse production is visible in the Netherlands, whereas on a global scale growth continues very rapidly.

Even the windows of the greenhouses are dependent on petroleum. An estimated 90% of greenhouses in the Mediterranean don’t use glass but transparent plastic instead that allows the desired wavelengths to pass through the greenhouse.

Pesticide dependence.  Individual studies tend to find a relatively small decrease in yield for farmers who don’t use pesticides. These estimates can’t be reliably extrapolated however, as such farmers inevitably benefit indirectly from other farmers who do use pesticides on their crops, thereby never allowing pests to gain a foothold in the first place.  Because of the international scale of modern agriculture and our industrial food system as well as a drastic reduction in biodiversity in our plants, a variety of plant pathogens have managed to spread to different species and continents. This has necessitated a growing cocktail of a wide variety of different pesticides, the health effects of which are largely unknown.  Growing plants in greenhouses in particular is nearly impossible without pesticides, due to a variety of factors. Ultraviolet light, which is blocked by glass, harms certain pathogens, but also causes plants to produce compounds that reduce their sensitivity to pathogens. The reduced day-night temperature variation and relatively high humidity also makes greenhouse plants more vulnerable to a variety of pathogens than traditional food production systems.

Irrigation.  Places like Israel depend on desalination for water, which is only accomplished by use of high amounts of energy. Israel also depends on water that is relatively high in salt, so to avoid salt building up in the soil, sprinkler installations are used that require very little water to effectively treat the plants.  Using pre-industrial methods instead, like building irrigation canals, would cause salt to build up in the soil due to evaporation, whereas a lack of irrigation would drastically reduce yields and require a switch to completely different crops.

Nitrogen and Phosphorus.  The two main nutrients we use as fertilizer are nitrogen and phosphorus. Nitrogen is removed from the atmosphere through the Habers-Bosch process, which consists for 80% of nitrogen. This requires the use of natural gas, an estimated 3-5% of global natural gas production is used for this purpose alone. Nearly 80% of nitrogen found in our body originates from this process.

Phosphate is mined from phosphate rock. Because the world’s grasslands are losing phosphorus through various processes, it’s estimated that phosphate application on grassland will have to quadruple between 2005 and 2050, to increase production by the 80% expected to be necessary over that time period.

In total, it’s thought that phosphorus production will have to more than double by 2050 compared to 2005, just to keep up with demand. It’s not clear how much further phosphate rock production can grow. Some estimates are that phosphate rock production will peak by 2027, even as depletion of our soils will merely get worse.

Because rising CO2 concentrations increase the growth rate of plants, places that are currently in phosphorus balance may become gradually depleted as a result and ultimately dependent on phosphorus application by humans. This happens to peripheral regions, where the fertility of land is extracted as the land is valued less than in regions that are highly populated and seen as economically valuable.

While many regions witness phosphorus depletion, places like the Netherlands are victim to over nourishment. Crops are shipped from marginal lands in places like Brazil to factory farm animals in the Netherlands, where animals defecate and the phosphorus is released in excessive amounts into our soils and waters. This is enabled by industrial agriculture’s international orientation, without which minerals like phosphorus would be recycled in a local ecosystem in a more sustainable fashion.

Peak farmland

Today we have less fertile land around the world, due to factors like those outlined above. Some places that used to be farmed have become burdened by too many heavy metals and other pollutants to still be capable of reliably producing food. In China, 19.4% of arable land is estimated to be contaminated with heavy metals. This share will continue to rise in the coming years, as well as the degree of contamination.

It is estimated that the world lost a third of its arable land between 1975 and 2015. Factors that are important here are not just chemical contamination, but also erosion of fertile soils by wind and water, as well as the covering of fertile farmland with human infrastructure. Climate change also contributes to making soils more vulnerable to erosion.  Thus today we find ourselves having to feed more people, with less arable land. What proved possible for our ancestors won’t be possible for us, simply because you can’t go back to farming arable land that no longer exists.

Soil compaction is a harmful process that damages the fertility of our soils. Depending on the depth at which the compaction takes place, the compaction is often practically irreversible.  Unfortunately, governments have a tendency to use poor metrics to estimate soil compaction. It’s estimated for example, that individual humans lead to greater soil compaction than large machinery, simply because the weight of such machinery can be spread out further across the soil through use of big wide tires.

The difference here however, is that topsoil compaction is far less harmless than subsoil compaction. The impact of humans and other animals takes place mostly at the topsoil, because humans and other animals put high pressure at small locations.

Heavy machinery like tractors on the other hand, execute far higher pressure when measured over a broader area. The average tractor has increased in weight from 2 tons in 1950 to 7 tons today, which is more than the largest elephants. The broad tires of the machinery might lead to less harm to the topsoil, but causes greater harm to the subsoil.
The topsoil is quite rapidly restored by earthworms, moles and other lifeforms, who dig through the ground and loosen the soil, allowing roots to penetrate the soil again. The subsoil on the other hand takes much longer to recover when compacted, because the subsoil is home to comparatively few lifeforms.

This prohibits roots from growing into the subsoil and redistributing scarce nutrients up into the higher soils, as well as preventing the subsoil from retaining water, often creating puddles of water above the soil that end up damaging the plants.

In the short term (up to around six years), yields are greatly reduced by subsoil compaction, but there are also smaller more persistent effects that linger for decades. One study estimated a permanent reduction in yield for wheat of 1.5% and 6% for two different fields respectively, as a result of the use of heavy machinery.

Effects are likely to be worse today, due to the even heavier machinery now in use. In addition, plants that naturally root deeper than wheat, like many edible nut species, would have even worse effectively permanent reductions in yield than wheat. Subsoil compaction represents a long-term reduction in the diversity of life that a plot of land could harbor otherwise.

Irreversible transitions.  The problems seen above are a consequence of the general rule of thumb with most technologies that it’s easier to adapt to them than to let go of them again. Our innovations in agriculture are no exception, they’re schoolbook examples.  This transition to modern technology in agriculture produces long-term consequences, that can be concealed in the short-term through use of more new technologies. For example, rising CO2 concentrations make plants more vulnerable to pathogens, but farmers who happily spray pesticides probably don’t realize this until they suddenly have to return to growing crops without pesticides.

Land consolidation.  The number of farms in existence today has decreased drastically, as many people have quit the farming business due to scale advantages that effectively allowed just a few farm business to survive. Whereas formerly people would have guarded the crops growing in their backyard, today farmland is often in the hands of nameless corporations. In the event of a food shortage, the theft of food crops will thus be increasingly difficult to prohibit.

A scenario for the future: Marauding 21st century Hunter-Gatherers

Ownership and control over food producing resources will probably prove difficult to enforce in many places. Even people who own small plots of land will have difficulty growing crops and keeping the harvest for themselves if they do not live on the land.

A scenario where people grow their own food appears to be far less likely than a scenario where nomadic groups of people begin to plunder the countryside. This is what effectively seems to have happened in the Roman empire, where nomadic tribes invaded and local bands of Roman citizens known as Bagaudae began pillaging the countryside.

Eventually, as food that can be plundered from homes and fields begins to run out, people would be forced to depend solely on whatever grows in the countryside. Our changing climate means that this may prove to be a more viable strategy than we might expect.

In Europe, some Middle Eastern refugees already appear to be adapting to a migratory lifestyle, incorporating wild foods into their diet. A spike in mushroom poisoning cases has been seen in Germany as a consequence of refugees eating wild mushrooms.

It seems to me that we should expect to see a lot more of this in the years ahead. Our food production system has evolved in a fashion that is difficult to roll back even when it becomes necessary. It appears more likely to cease working altogether than to become less complex.

This entry was posted in Agriculture, Peak Food, Phosphorus, Scientists, Soil, Ugo Bardi and tagged , , . Bookmark the permalink.

6 Responses to After a collapse will people grow their own food or plunder others?

  1. Ugo Bardi says:

    Hi, there, Alice. This post is not mine. I have no idea who keeps the blog “The Seneca Effect” on worldpress, but my “Seneca” blog is on blogger.

    Overall, I would say that I tend to agree in a general way on what this post says, but it is not mine. Anyway, it looks like by now I am associated with the concept of the “Seneca Cliff” in all its forms. My book titled “The Seneca Effect” is going to come out, probably in early May

    • energyskeptic says:

      Dear Dr. Bardi,

      I am mortified! I associate you so strongly with this concept I didn’t give it a second thought. I’ve changed the post to reflect this, thanks for letting me know. I’ve read a string of about 5 books about what the collapse of the Roman empire and of course, little is known about the fate of the people afterwards, except that the archeological record goes rather blank for centuries of well-crafted goods, homes, and so on.

  2. Jan Lundberg says:

    There was more that could have been said, such as the 9/10ths of the calories going into the production of a piece of food’s coming from fossil fuels. And that the average piece of food in the modern world travels 1,500 miles from farm to plate. And, that the big Achilles heel for the corporate consumer economy is the maritime shipping industry’s complete petroleum dependence — the wiggle room on that, and progress with “green systems”, are about nil.
    Great job, whoever dunnit (Ugo Bardi has disavowed it).

  3. Rosenkohl says:

    This is just and aside in the article, but frankly nonsense: “In Europe, some Middle Eastern refugees already appear to be adapting to a migratory lifestyle, incorporating wild foods into their diet. A spike in mushroom poisoning cases has been seen in Germany as a consequence of refugees eating wild mushrooms. It seems to me that we should expect to see a lot more of this in the years ahead”

    – To collect “wild food”, including plants, leafs, berries, fruits and mushrooms, is no particular habit of migrants, many people do so. Of course, wild collected food is very low on calories, and nobody can subsist on it. The blog appears to be by an author from Netherlands, where collecting mushrooms is banned in order to protect the wildlife in the limited remaining forrests; which is why many Dutch visit German forrests in order to collect mushrooms.

    The number of mushroom poisonings is mostly correlated to the number of available mushrooms. In years like 2010, 2014 or 2015, there were far more poisonings than in a dry year such as 2016 (see statistics for northern Germany Trend of german mushrooms deaths has been declining since 1980 ( There were 0 deaths in 2014, 2 in 2015, 1 in 2016; while one of the deaths in 2015 and 2016 each habe been refugees.

    Some Syrians apparently confused the deadly poisonous Amanita phalloides or Amanita verna with edible Amanita ovoidea, which can be found in southern Europe and the Mediterranean region.

  4. tagio says:

    Very interesting speculation. However, the remoteness from food production and concentration of the population in cities is also a problem for the “marauding lifestyle.” Yes, marauding may seem to be the way to go. However, the lack of fossil fuels for transport and the very remoteness from the food will render the marauding period of shorter duration (I would hazard), than the duration of such activities following the “Fall of Rome.” It’s not like the marauders will have horses that can feed themselves along the way. It’s no accident that apocalyptic movies like Road Warrior show gangs on motorcycles, which require far less gas. (Problem there though, modern gas with ethanol quickly becomes useless, a fact which all the apocalyptic movies and tv shows ignore.)And this is why preppers recommend being at least 100 miles or so from all cities. Even so, starving people will go look for food and the sheer numbers of migrants will likely be daunting.

    Possibly watch what happens in Venezuela. As far as I know, people in cities there are eating cats and dogs, and pillaging from one another, but so far I haven’t heard of any serious marauding into the countryside for livestock and grains. Of course, the government is still trying to keep a lid on it.

    • energyskeptic says:

      I read a dystopian book about what happens in Oregon after a collapse, there was the usual cannibalism, but also armies of bicyclists from Portland riding all over the place to wage war and take goods. But I think in most troubled third world countries, there are roadblocks everywhere, so that’ll slow them down.

      Venezuela is interesting. Many posts under Collapsed/Collapsed and Collapsing nations discuss how people cope. I also have book reviews of what happened in Germany after WWII and during WWI in 1) After the Reich at and 2) Englund’s “The Beauty and the Sorrow” and in Russia: Russia’s Food Policies and Globalization

      In WWI the German public took trains out into the country to try to exchange silverware or whatever else they had for food, and farmers complained there were so many of them walking around their fields they couldn’t keep track of them, and I’m sure some took free food back with them. Wealthier Germans had large gardens. Hoarding was not allowed, and groups of citizens would go house to house to try to find hoarded food, and got quite good at discovering hidden caches.