Terraforming: A Primer

“Terraformation, literally meaning “Earthing-shaping”, is the hypothetical process of modifying the atmosphere, volatile components, temperature, surface topography or ecology of any celestial body to be similar to the environment on Earth, making it habitable for Earth life.”

Why should “similar to Earth” be the end goal of terraformation? Our Earth is filled with microplastics, greenhouse gases, dangerous weather, and poor conditions for agriculture on most of the land. It can barely sustain the 8 billion people alive now, even with a substantial percentage of them consuming far less than their fare share of resources. Before we think about terraforming other planets, let’s think about how to terraform Earth into an Earth that doesn’t suck.

Terraforming a planet is, for now, impossible. But the technology that would be used for terraforming has a ton of critical real world applications. These technologies fall into roughly seven categories: Geoengineering, Habitat Restoration, Water Management, Urban Environment, Weather, Agriculture, and Biosphere. A lot of this tech can be battle hardened here on Earth before we eventually can deploy it on Venus or Mars, the two most likely candidates for early terraformation.

Controlling the Climate with Geoengineering

The first thing we have to manage in order to make another planet habitable is the temperate and atmospheric composition. Controlling these requires large-scale interventions like reflecting sunlight to cool a planet or capturing gases to improve atmosphere. On Earth, these interventions may be essential for reducing the effects of climate change. There are a few key technologies to be aware of in this space.

Temperature control through solar radiation management

Sunlight is what makes the planet hot. If we can stop some percentage of that sunlight from hitting the Earth, it will be less hot. How do we stop the sunlight? Make the air shinier. As absurd as that sounds, there a few very promising techniques for increasing atmospheric albedo (“albedo” is just a fancy word for shininess). Stratospheric aerosol injection releases reflective particles into the stratosphere. The primary candidate for this is sulfur dioxide, which is emitted during volcanic eruptions and is responsible for the cooling effect of volcanoes. Interestingly cargo ships used to emit SO2, which meaningfully decreased greenhouse gas effect, but international regulation driven by concerns over acid rain forced them to add air scrubbers, which seems to have just moved emission from the air to the ocean. Another option is marine cloud brightening, where seawater is sprayed into the atmosphere, making clouds more reflective using safe materials (in this case, sea salt).

Temperature control through CO2 regulation

Carbon dioxide is the substance primarily responsible for the greenhouse gas effect, trapping excess heat on Earth. “Excess”, of course, is relative. On Mars, with an average surface temperature of -85°F, we could increase CO2 levels to create a thicker atmosphere that traps more heat. On Venus, we have a similar problem to Earth, where atmospheric CO2 levels are keeping the planet hotter than we’d like (although on Venus it’s about 800° too hot). There are two ways to remove CO2 from the air: with machines and with plants. Direct air capture uses machines that push air through a filter, extracting CO2 and then sequester it in some way, typically either moving it underground or using it to produce synthetic fuels. The more natural route is bioenergy with carbon capture and storage (BECCS), which involves growing CO2-absorbing biomass (a fancy word for plants), burning it to produce energy, and capturing the emissions. In both cases, capturing CO2 requires much less energy to do at the source of production than to remove it from ambient atmosphere.

Ocean Management

I don’t think I need to explain why water is important. On Earth the distinction between the salty oceans and drinkable fresh water bodies feels intuitively important, but in the context of terraformation it’s actually not a very important consideration. All bodies of water residing on mineral-rich land will leach those minerals over time (i.e. millions of years) and become saltier. With desalination technology like solar desalination and graphene filters becoming much more energy efficient, we can think of any planetary water, salty or otherwise, as useful to humans longterm. That said, we don’t “use” the majority of water on Earth, but it plays a very important role in maintaining climate stability. In terraforming another planet, it might make sense to cover a large portion of land in water. Here on Earth, we can alter the composition of our oceans to improve climate conditions. The key is maximizing ocean productivity, which essentially is increasing the total amount of phytoplankton (tiny floating ocean plants), by improve nutrient profile of marine waters. This can be done through ocean fertilization, where we add nutrients like iron to the ocean, or artificial upwelling, where we bring nutrient-rich ocean deep ocean water closer to the surface.

Weather Modification

As you are hopefully starting to see, preserving, restoring, and creating natural environments is all about maintaining a very delicate balance. There are only narrow ranges where everything “works” and humans can thrive. Only a small percentage of the land on Earth has what I would call optimal weather. The defining characteristic of good and bad weather on Earth hinges on the amount of precipitation. Since humans existed, they have prayed to gods for better weather. Prayers are for one of two things: more weather and less weather. Fortunately, we can give the gods a break and handle both of these challenges ourselves.

More Weather: Cloud Seeding

Moving water around for drinking, plumbing, agriculture, and industrial uses is incredibly expensive, and droughts have catastrophic implications for all types of human societies. Cloud seeding is the ability to create rainfall on demand. Not all clouds are rainclouds — if they lack sufficient ice crystals or water droplets, the cloud will not begin to condense and it will simply dissipate. By spraying substances like silver iodide, or in some cases just salt, tiny particles act as additional nuclei around which water droplets can form and grow, encouraging the formation of rain drops, leading to, you guessed it, rain. Cloud seeding is not new technology, and was used as far back as the Vietnam War to disrupt supply chains. There are still significant hurdles to implement cloud seed at scale safely and cheaply, but many it’s a significant priority for many countries that regularly experience drought. It’s worth noting that cloud seeding works not only for rain, but for snow as well, and is regularly used by ski resorts to improve snowfall.

Less Weather: Hurricane Mitigation

You know what they say about too much of a good thing? While small rainstorms are essential for our existing agriculture and sanitation infrastructure, hurricanes (which are just really, really big rainstorms) can be incredibly damaging. Urbanization is one cause of this — human developments are obviously vulnerable to extreme conditions, but even in natural environments unusual weather events like hurricanes can leach nutrients from soil which can hamper plant growth for extended periods of time. Even so-called “natural” weather events (i.e. unrelated to human-caused climate change) can be catastrophic to life on Earth (remember the Ice Age?), and having tools to control these events is critical for our success as a species either on Earth or elsewhere. There are several ideas for how to do this, including cooling sea surfaces and blasting aerosols to dissipate hurricanes, but so far these approaches have been met with quite a bit of skepticism. Climate change increases the intensity of hurricanes, so building mitigation technology will be more important than ever.

Habitat Restoration and Afforestation

Before we try to terraform a whole planet, we should first know how to turn the Sahara into a rainforest. Or at the very least, restore degraded ecosystems to self-sustaining environments. Thriving natural space can make environments much more livable, decreasing the burden on atmospheric control to exactly match human needs. Just look at what happens to the climate in cities with no green space. There are two approaches to getting plants to grow in difficult environments: make the environments friendlier to plants and make the plants more resistant to difficult environments.

(As a quick aside, I found the idea of “desert greening” to be very unintuitive at first. These are fundamentally very hot, dry areas. So even if you bring a bunch of plants and water, it will all dry up eventually, right? This overlooks the extent to which a local climate can be mostly closed-loop. When it rains in the desert, water that forms small pools evaporates very quickly in the sun. When it rains in the forest, water is trapped in trees and in shade that protects it from evaporation. Those in turn keep huge areas cool and dark, increasing the amount of water that does evaporate or run off. Now, there is clearly a cold start problem here. Once a forest is gone, the ground becomes hot and loses its ability to retain water, so it’s hard to grow anything. What’s so cool about desert greening though, is that if you add a bunch of plants and a bunch of water to an area of the desert, all that water can just stay there and support the local ecosystem.)

Modifying Environments

Although currently difficult to implement at massive scale, there are a variety of interventions for making deserts arable. The first is albedo (remember, that means shiny) modification, where you apply materials to desert surfaces that reduce heat absorption, increasing the likelihood of rainfall and keeping the area cooler. The other method is aquifer recharge, where we store excess rainwater (or desalinated water) underground to use as a more sustainable water source in arid regions. Both of these create conditions that are conducive to plant growth, and can support agriculture and afforestation.

Modifying Plants

Life exists on Earth in the most unlikely places. There are plants that live hundred of feet below sea level and tens of thousands of feet above it. Genetic modification of organisms lets us create plants that can thrive in difficult environments, which could help solve the cold-start problem of greening harsh climates. Once environments are improved, there is also value in modifying plants to make them generally hardier and faster growing. This can be done with trees, to make them grow more quickly, absorb more CO2, and be more resistant to disease and climate stress. Unfortunately, creating new plant species is still really expensive and slow, but new advances in AI can improve the cost and speed of this process by a huge amount. Using genome foundation models, researchers can efficiently generate new plant species by leveraging comprehensive "dictionaries" of DNA and RNA site functions to predict and optimize genetic modifications.

Urban Environment Management

Now we get to the part of the terraformation primer that acknowledges that humans are Earth creatures and cities are our habitats. When we talk about a location (whether that’s a place on Earth or another planet) being “habitable” for humans, we really mean “can we build a city there?”. The way we construct a city, both from an urban planning perspective and in terms of environmental impact, have an enormous effect on how livable the land on which it’s constructed becomes. Urbanism technology is probably too vast a space to cover in this short overview, and includes social and governance innovations that are not “technology” in the traditional sense, so I’ll cover a few interesting pieces of frontier tech important for terraforming urban landscapes.

Synthetic Biology for Environmental Remediation

Humans create a lot of junk. A lot of this junk ends up in landfills and oceans far away from where we live, so the downstream consequences of all the junk is relatively abstracted away from us. But the path this junk takes to go from our bodies and our homes to an abstractable faraway location is an important consideration. Poorly managed sewage, garbage, and other sanitation needs in a city can make it entirely unlivable for humans. When sanitation is mismanaged, as it is to some extent in every city in the world, it must be fixed in a minimally disruptive way, because cities are filled with humans that can’t be easily displaced. Even if problems look similar (e.g. microplastics in water), the solution in an urban context may look very different. Synthetic biology, where microorganisms are engineered to perform various useful tasks, has enormous potential improve urban conditions. Bioremediation can use microorganisms to break down pollutants in parks or drinking water, essentially by training them to use chemicals that are harmful to humans as nutrients. A similar process can also be done with tiny plants (phytoremediation) or fungi (mycoremediation) depending on the setting.

Sustainable Agriculture

Right now we don’t have great ways to produce food at scale without agriculture. Yes, there is lab-grown meat, but for now agriculture with a very reliable way to produce foods that are both  calorically useful and psychologically delightful. Developing efficient agricultural practices that control environmental impact can help us ensure food security on Earth and beyond. It’s impossible to grow crops on most of the Earth. There are two interesting uses of terraformation technology in agriculture: using agriculture to modify environments, and using new technologies to practice agriculture in difficult locations.

Soil Carbon Sequestration

By capturing atmospheric CO2 and storing it in soil, we can actually improve the nutrient profile of the soil and increase the overall agricultural yield. “Capturing carbon” just means growing plants, which use photosynthesis to convert CO2 to organic matter, die and biodegrade, filling the soil with carbon that used to be in the air. This is called soil carbon sequestration and there are a few approaches. Cover cropping involves growing hardy, high-coverage plants like clover or rye between planting seasons. Agroforestry integrates trees and shrubs into agricultural landscapes, which has the added benefit of increasing biodiversity and preventing erosion.

Alternative Farming

Vertical farming is a way to grow plants in vertically stacked layers indoors. These layers can be constructed in a relatively small space, meaning the optimal indoor climate can be more easily maintained. This is the most common setup for hydroponics and aeroponics, where plants are grown in nutrient-rich water or mist instead of soil. If you look at what is currently grown in vertical farms, it’s mostly lettuce, herbs, and some small “fruits” like strawberries or tomatoes. What do all these things have in common? They have almost no calories. There is no free energy in the universe, so plants can only provide as much energy as goes into them. Although artificial lighting can replace sunlight for photosynthesis, it is very energy-intensive to grow calorically-dense food. Because of this reality, a lot of people have started to discount vertical farming as unserious technology in a terraforming context. But if you believe that energy will get a lot cheaper (which is plausible if nuclear fusion becomes tractable), vertical farming gets a lot more appealing.

Entering the Biosphere

Terraformation is primarily an “outdoor” concept, but if the end goal is making other planets habitable, we can also just get really good at making indoor spaces that serve all the purposes of natural habitats. What would it look like to build fully self-sustaining ecosystems on the North Pole, at the bottom of the ocean, or in the middle of the desert? For humans to live off the grid, they have to be in areas rich with natural resources. Eventually we’d like find ways to make new places resource-rich in this way, but until then there are ways to construct “biospheres” with fully closed-loop artificial ecosystems that can provide humans with everything they need to not only survive but lead fulfilling and healthy lives. There is a ton of interesting tech here that has immediate on-Earth applications and eventually may be used to build full-fledged biospheres. These include atmosphere management systems, water and waste recycling, complex sensor systems, biofilters, and much more.

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If you were born in the last fifty years and grew up around well intentioned liberals, there is a high probability you, or people close to you, believe climate change and pollution is leading the Earth down an inexorable path towards devastation, and although we can do our part to slow it down carpooling, recycling, eating less meat, taking fewer flights, shopping sustainably, etc., the world will inevitably become much less habitable unless we can achieve radical degrowth and corporate curtailment. And if you grew up in a different political context, maybe you believe that climate anxieties are largely a product of fear-mongering leftist media and the consequences of climate change, if any, will be far more attenuated than scientists claim. In either case, the deterioration of natural environments is a critically important issue, but degrowth and social engineering are not solutions. Exactly why this to be true can be covered in another essay, but the only path forward is to gain ultimately technological dominion over our environments.

Look at the last four hundred years. Things on Earth have improved in basically every conceivable category except climate. We have better technology, healthcare, government, social freedoms, and access to food than ever before. Our natural environments, through pollution, development, and climate change, are basically the only thing that has worsened. We can develop the technology and energy capacity to reverse this, but this only gets us so far. Even in its primitive state, the Earth is not optimized for humans. If we strive for a future with trillions of thriving humans, we’ll have to figure out not only how to fix our climate, but create paradises across the solar system. That is terraformation, and we don’t have time to waste.

Notes

1. I’ve heard many of my peers say things like “the Earth would be better off without people”, and bristle at the idea that humans should be striving to colonize other planets. It’s hard for me to engage seriously with any non-humanist argument. Yes, humans are destructive. So entropy in the universe increases. The issue with the destruction of natural environments is not an immanently moral one, but a practical consideration for future and human populations — nature is materially and psychologically important to the experience of being human. Growth is awesome, let’s make more happy humans. (Tough to make a philosophically rigorous argument in a few sentence note — this probably deserves its own essay.)
2. My ideal vision of the future is one where AI and advanced robotics free humans to enjoy life in their ancestral form. This likely requires terraformation. But it’s worth noting that this is a matter of personal preference. There are alternative paths forward for humans where our environments don’t matter. Mind upload or immersive VR might be futures where human experience becomes entirely divorced from their physical environments. For now, this is not an exciting future to me. Ask me again when the singularity gets here, but until then I think it’s worth learning to control planets.