Homo Subterraneous

In today’s modern world, 26% of Earth’s surface land is dedicated to raising and then slaughtering 23,000,000,000 (23 billion) chickens, 1.5 billion cattle, 1 billion pigs, and 1 billion sheep. Out of these, only the sheep live anything approaching the semblance of humane existence.

At least 97% of calories fed to captive-bred meat animals are used to keep the animal alive. The remaining 3% is then collected from the carcass and sold as meat. Setting aside the squalid and awful existence these animals lead, I state this fact to demonstrate the profound inefficiency of our modern meat industry. For every 1kg of beef produced, 25kg of grain and 10kg of water are consumed. If we were to just divert that food directly to individuals, we could feed an additional 3.5 billion people.

This is not meant to be an essay on the evils of factory farming,¹ the meat industry is just one poignant example of mankind’s self-serving and dramatic remaking of the natural world.

Researchers have named our current geological epoch the Anthropocene. In the era of the Anthropocene, human activity changes the Earth and its systems more than all natural processes combined. Our refashioning of Earth has come at the expense of nearly every other life form on the planet. Across species and habitats, biodiversity is in freefall. The specific causes may differ (agricultural runoff, urban sprawl, strip mining, plastic pollution, greenhouse emissions, light pollution, et cetera); but at the root, the common factor is human activity.

I believe we have justified this subjugation of Nature because we have considered ourselves distinct and above the pyramid of terrestrial life (Fig. 1). Who may blame us for exploiting Mother Earth, when she exists below us? A mere resource to extract and divert as we see fit?

Figure 1: 1579 drawing of the Great Chain of Being by Didacus Valades, Rhetorica Christiana. Mankind is on the third level, below only God and angels.

If we are to overcome the current ecological crisis, it will necessitate a paradigm shift in the way humanity interacts with Nature. Central to this shift will be the acknowledgment that natural life has inherent value and deserves to be protected and nourished.

In particular, I believe it will necessitate the dramatic expansion and utilization of an urban underground. By physically relocating the human subject below the surface, two objectives are met. First, it subverts the historical framework that presents humanity as divine ruler above natural life. Second, it provides Mother Earth the opportunity to recuperate from the significant damage inflicted upon her. Recent estimates predict that constructing nature preserves over 50% of the Earth’s surface land and sea from human development would also preserve 90% of remaining species.

Though I have motivated this discussion with a focus on more abstract natural ideas; I believe there also exist a number of tangible benefits to relocating the bulk of human activity belowground. As a result, this work should be viewed as a persuasive piece motivating urban planners and municipalities around the world to seriously consider subterra in their visions of the future.

As shelter

Most historic human uses of the underground have been related to shelter. In the 1960s, the United States set up the Community Fallout Shelter Program. Designed to protect U.S. citizens in the event of thermonuclear war with the Soviets, the program constructed large-scale underground bunkers across the country. That said, the underground has been looked upon for shelter before; long before the USA or the Soviet Union ever existed.

Ancient Cappadocian societies utilized a network of at least 22 underground cities for daily life since at least 370 BC. These cities were labrynthine mazes literally carved underfoot (Fig. 2). Though frustratingly little is currently known of the master builders who constructed them; modern theories posit 2 rationales for the existence of these cities.

Figure 2: Reproduction of figures 21b, 6a, 23, and 2 as found in Aydan & Ulusay's excellent 2013 paper. Panels (a), (b), and (c) are specific to Derinkuyu ("deep well" in Cappadocian Greek), one of 22 underground cities discovered in the region.

The first theory is that dramatic surface temperature fluctuations forced the inhabitants to seek shelter underground. Temperature measurements from 2007 provide stark evidence for this argument: surface temperatures ranged from -18C/-0.4F in January to 40C/104F in July. These extreme fluctuations stand in stark contrast to the steady range (-5C/23F - 10C/50F) found in the 5th and 7th underground floors of Derinkuyu (Fig. 2c).

The second considers the defensive aspect of these structures. Evidence for this theory exists as well. The current oldest known primary source of these people comes from Xenophon’s Anabasis written circa 370 BC. The Anabasis is a third-person narrative commemorating Cyrus the Younger’s military expedition to capture the throne of Persia. As Cyrus’ mercenary band moves through Cappadocia, Xenophon describes the cities they encounter: “The houses here were underground, with a mouth like that of a well, but spacious below; and while entrances were tunnelled down for the beasts of burden, the human inhabitants descended by a ladder.” Led by Xenophon, the army then shelters semi-peacefully among the citizens. Cappadocia, located in Central Anatolia, lies directly between the Mediterranean and Black Sea. An important strategic area, Xenophon’s account proves its residents saw a fair amount of conflict. It seems natural that its inhabitants would strive to develop easily defensible cities to shelter from invaders; Derinkuyu alone is predicted to have a potential capacity of 20,000 individuals.

Although little may be known about their way of life, what has survived are their monumental shelters. Be it protection from climate or roving bands of bloodthirsty soldiers, the archaeological sites across central Anatolia reminds us the underground can be a site of resilient shelter (Fig. 2). Through this lens, descending belowground may be viewed as returning to the protective womb of a divine being.

Though the nuclear threat is still omnipresent (and the underground does serve as a reasonable response), I’ll instead be focusing on the potential for ecological shelter underground. This is not because I view the nuclear issue as unimportant, it’s simply because there already exist numerous anti-nuclear movements who have thought extensively on the issue.

Anthropogenic climate change is driving systemic and dramatic changes in global weather patterns. Unpredictable flooding, prolonged droughts, devastating cyclones, and punishing heatwaves have all been explicitly linked to greenhouse gas emissions. With this knowledge, the concept of an underground ‘shelter’ must once again be deployed. Instead of sheltering us from human-caused nuclear fallout; it may now shelter us from human-caused ecological apocalypse.

The insulating nature of earth has already been illustrated by the significant differences in temperature above and below ground in Cappadocia. As heatwaves increase in frequency and intensity, the underground may serve as seasonal shelter for broad swaths of humanity. Generally, the first 10-15 meters below the surface shows seasonal fluctuations in temperature. However, temperatures below 15 meters are relatively stable year round. This is especially pertinent for urban planners considering how to deal with the ‘urban heat island effect’, where the paved city continually accrues heat.

In geologic timescales, the Anthropocene is still in its infancy. The exact consequences of human activity are still being debated and observed in real-time. As much as I would like to believe that current climate projections are overly pessimistic, I understand that such desires are naive. When considering the human-centered spaces of tomorrow, designers should “hope for the best, plan for the worst.” The underground may not be ideal, but it offers one well-supported option for shelter from disaster.

As sustainable space

Beyond serving as shelter to carry us through the effects of unsustainable human activity, the underground may also serve as a site for sustainable urban development.

In contrast with surface settlements, the underground is a self-contained system (Fig. 3). Emissions, pollutants, and waste generated within any underground space may only exit the boundaries of the space with explicit permission. One excellent example of this is the recent interest in underground farming practices.

Figure 3: Schematic of an arbitrary underground space.

Since the Haber-Bosch process ushered in the Third Agricultural Revolution, humanity has pumped out significant quantities of nitrogen-enriched fertilizer. This fertilizer is mixed with local topsoil and seeded with acres upon acres of identical crop.² This is particularly galling when we realize that the natural state of life is not one of staid uniformity, but of rich biodiversity. The pre-existing forest/swamp/desert/plain that was bulldozed over to plant crops were the homes of millions of unique and local organisms. There is simply no natural analog for neat grids of genetically clonal crops growing in artificially enriched soil. The repercussions are extensive, but let’s focus on just one: agricultural runoff.

Runoff is the general term used to describe water that flows over land. Examples include rain pouring down a hill, the soapy water that runs off the pavement during a car wash, or a natural free-flowing river. As the water flows to its final destination, the water mixes with and ingests whatever happens to be in its path. In the case of agricultural runoff, any water that runs over farmland mixes with all the human-applied chemicals and pesticides applied to modern crops. These additives may be excellent for growing man-made corn, but they are wholly unsuited for stochastic infusion with the outside environment.³ This effect is nullified when one farms underground (Fig. 4).

Figure 4: Underground farming concept proposed by Professor Rifatt's group at the University of Nottingham. Note the carbon capture/release.

In London, 33 meters below the surface, fields of microgreens are being grown by the company Growing Underground. First envisioned at the University of Nottingham, the company aims to demonstrate the commercial viability of large-scale underground farming. In addition to removing the problem of polluting runoff, the method also uses significantly less water and energy for every calorie grown. Though still small in scale, Growing Underground’s pilot project in London is working to demonstrate the the feasibility and cost effectiveness of underground farming.

Agriculture is one specific example of a broader possibility. The underground may serve as a general site to do things that are ugly; but currently necessary, for human existence.⁴ By burying any process that generates waste, we automatically entomb any waste as it is generated (Fig. 3). Though we must learn to generate less and less waste, until we reach that point; the underground may be a space to contain this ‘bridge’ waste.

In addition to storing human excess, the underground may also serve as a storage area for natural excess. In the Netherlands, parts of Rotterdam now experience routine and sudden flooding. To combat this, local municipalities have constructed large underground reservoirs for excess water during storm conditions (Fig. 5). In 2001, Hong Kong commissioned the development of the Tai Hang Tung Storage Scheme (THTSS). Over 130 meters long and wide, it can intercept up to 70 m³ of water per second.

Figure 5: Water Square in Rotterdam designed by De Urbanisten. Through angled surfaces, rainwater is diverted through underground pipes to reservoirs. When not in use, the Square also functions as a multipurpose park for the neighborhood.

Regardless of the specific process being discussed, the enclosed nature of any underground structure makes it a viable candidate for sustainable urbanism.

As a canvas

At its core, the distinction between designing above-ground and below-ground is one of negative space.

Consider the work of a sculptor. Instead of constructing a collection of rocks upwards; their vision is achieved by chiseling away at a large, pre-existing slab of material. In the same manner, underground structures are primarily defined not by what was built; but what was taken away (Fig. 3).

This delineation is unique and affords architects, planners, and designers entirely new creative modalities that deserve to be considered. In Cappadocia, a number of builders elected to carve benches and furniture directly into the walls of their abode. Another excellent vision for underground structures can be found in BNKR Arquitectura’s proposed Earthscraper.

Initially envisioned for the heart of the Plaza de la Constitucion in Mexico City, the Earthscraper is imagined as a 300 meter deep inverted pyramid. The pyramidal design simultaneously evokes the mesoamerican pyramids that dot Mexico, and lessens the lateral pressure applied by the Earth. To allow natural light, BNKR proposed constructing the surface-level base out of hardened glass. Thus, natural sunlight may reach the depths of the Earthscraper while still maintaining the historic spirit of the Plaza de la Constitucion (Fig. 6).

Figure 6: BNKR Arquitectura's proposed Earthscraper in Mexico City.

Let’s consider another area where the underground would enable new creative possibilities: mapping. Recall the maps of Derinkuyu presented by Aydan & Ulusay 2013 (Fig. 2a, 2b). Though a valiant effort, I’m unsure anybody could solely use these two maps to navigate to a particular room in Derinkuyu. Deciding how best to represent underground space is a challenging problem; all the more because most historical maps have been top-down 2D representations. That said, the challenge is not insurmountable. Virtual reality and dynamic 3-dimensional maps offer possible methods by which humans can understand and visualize underground spaces. Deciding how to best describe subterra and place the human subject within it represents an exciting new avenue of mapmaking. Anyone interested in the future of cartography, should necessarily be excited about the future possibilities of mapping the underground.

Finally, let’s think about the boundaries between the underground and the surface. Reconsider Figure 3. Imagine an individual, Billy Bob, living within the subsurface. If Billy Bob was inclined to exit the subsurface, he might construct a vertical tunnel extending perpendicular to the floor of his underground abode (imagine a ladder or elevator, 90^∘ to the floor). Alternatively, Billy Bob might tunnel horizontally, parallel to the subsurface floor until Billy Bob reaches the outside (imagine tunnelling through a mountain, 0^∘ to the floor). While these are the two typical ways of negotiating the interface between the subsurface and surface, they are not the only ways. Consider an angled tunnel extending from the subsurface to the surface (any angle to the floor, θ, where 30^∘ < θ < 40^∘).⁵ This ‘tunnel’ could serve as a gigantic slide! People on the outside could literally slide into the underground! Though slightly goofy, by imbuing the entrance with some whimsicality it might help alleviate some of the negative connotations people associate with the subsurface.

These examples are not comprehensive, but they illustrate the new opportunities available for urban planners and designers when considering the underground.

Rebuttals & Future Directions

To conclude, let me now turn to some common critiques I hear issued against underground urbanism.

The first concerns light and its availability. Obviously the underground is blanketed in perpetual shadow; one solution for this is to find ways to direct natural light into the space. This may be achieved through a design like the Earthscraper (Fig. 6), or by the construction of mirrors and fiber optic cables to tunnel natural light through the Earth. At the same time, I believe we need not solely rely on sunlight. Artificial illumination can be created to mimic the sun, while also offering fine-tuned control and novel possibilities for human-light interaction. Because underground spaces will be entirely man-made, designers may elect to place lights wherever they want without considering how their lights will interact with sunlight. Finally, I would argue humanity’s obsession with illumination is a modern phenomena. It was not until the invention of electricity that humans were afforded universal and ubiquitous access to light. James Turrell, a brilliant American artist, argues this has diminished our creative faculties: “We’re made for the light of a cave, and for twilight. Twilight is the time we see best. When we dim the light down, and the pupil opens, feeling comes out of the eye like touch. Then you really can feel color, and experience it."

Next, it’s worth discussing the cost and difficulties associated with constructing the underground. The average cost of tunnels and underground areas in Finland is ~$120 per m³, this is significantly lower than most areas. For example, in Hong Kong the average cost is ~$1,200 per m³. These differences can be chiefly attributed to different bedrock compositions. Finland’s bedrock is primarily composed of old Precambrian rocks amenable to the cheaper drill and blast excavation technique. In contrast, Hong Kong’s harder bedrock necessitates the use of tunnel boring machines. Elon Musk’s Boring Company claims to be developing next-generation, cheaper, electric boring machines, but have yet to release any for widespread use. Regardless, planners must pay careful attention to the specific composition of their local environment. These factors will play a large role in determining the depth, size, and ultimately function of any underground space created.

Finally, critics might claim that placing humanity below the surface would hamper the relationship between Mankind and Nature. On this point, I concede. Instead of attempting to carefully manage the Human-Nature relation, I believe humanity should seek to sever this connection.⁶ Human history and environmental subjugation go hand in hand; our relationship has always been extractive and largely predicated on developing new ways to exploit Earth’s biochemical systems for short-term gain. If we are genuine in our desire to heal the natural world, it will require a conscious effort to withdraw and scale down human interaction with nature.

This work should not be viewed as a comprehensive consideration of humanity and its relation to the subterranean; the underground is simply too expansive for any one piece to do it justice (Fig. 7). My goal is merely to instigate interest and curiosity in understanding and utilizing the underground. While I would prefer people to share in my genuine excitement about the possibilities of subterra, I am aware of the negative connotations associated with the underground.

That said, I am also acutely aware of the overwhelming extent of the current ecological crisis. I believe there is a future where humanity, acting out of desparation, is forced underground to escape the consequences of our actions. In such a world, the transition from Homo Sapiens to Homo Subterraneous will be mediated by necessity; not choice.

Figure 7: To-scale cross sectional view of the Earth. Note that the vast majority of human existence has so far been relegated to a thin slice of the continental crust. On this scale, that slice may be regarded as negligible.

Thanks to Katherine Horgan for helping translate Xenophon's Anabasis, to Thandi Nyambose and Professor Picon for reading drafts, and to John Murcko for pointing out the appropriate angle to a slide.

Arya Kaul (C) now - forever -> more essays