Extrapolating from this development in synthetic biology, Benjamin mused, “Maybe you could program a seed to grow into a house. Or maybe cities would be so in tune with ecosystems that they would grow over time, and then decay over time, too.” Synthetic biology might also help solve one of the biggest problems with new buildings, which is water leakage. Architects could design a building that is semi-permeable, with membranes that allow the circulation of air and water at various times. It’s easy to imagine a future architect fashioning just such a thing with BioCAD, with patches of permeable materials built right into the fabric of the walls. The water could be purified and used, and the air would become part of a natural cooling or heating system. This building might also use computer networks to monitor its community of local buildings to figure out when to gather solar energy and send it to the grid to share, and when to lower louvers to keep residents cool. “I sometimes imagine urban landscapes that are integrated into their ecosystems with a combination of vegetation and constructed materials,” Benjamin said. “They look almost like ruins in the jungle but they’re actually fully functional, occupied cities.”
Benjamin’s visions of the future end where his fellow synthetic-biology designer Rachel Armstrong’s begin. Armstrong, who is based in London, is an outspoken advocate for what she calls “the living city,” or urban structures that she told me we’d create in the same way we cook or garden. We met in a café in the heart of London, overlooking the busy Tottenham Court Road, and almost immediately Armstrong was imagining how she’d rebuild the city around us. “We’d have biofuel-generated façades, or technology based on algae,” she said, pointing at the windows. “You’d have surfaces creeping down buildings like icing. Strange, colored panels would glow through windows at night, and you’d have bioluminescent streetlights. Bridges will light up when we step on them.” She paused, but continued staring outside, deep in thought. “We’d keep the bones of buildings steel and concrete, but rewrap those spaces with increasingly more biological façades. Some will be porous and attract water; others will process human waste. Mold won’t be something you clean off a surface but will be something you garden.”
Armstrong is fascinated by bacteria and mold, which she and other synthetic-biology designers view as the building blocks of future cities. “We are full of microbes,” she asserted firmly. “Maybe instead of using environmental poisons to create healthier environments inside, we should be using probiotics.” Glowing bacteria could live in our ceilings, lighting up as the sun goes down. Other bacteria might purify the air, scrubbing out carbon. Every future urban home would be equipped with algae bioreactors for both fuel and food.
Her vision isn’t just science fiction. Recently, Armstrong worked with a group of biologists and designers who hope to use experimental proto-cells—basically, a few chemicals wrapped in a membrane—in a project that could prevent Venice from sinking into the water. Proto-cells are semi-biological, and can be designed to carry out very simple chemical processes. In Venice, engineers would release proto-cells into the water. Designed to prefer darkness, the proto-cells would quickly head for the rotting pilings beneath the city’s dwellings. Once attached to the wood, the cells would slowly undergo a chemical transformation in which their flexible membranes transformed into calcium shells. These calcium shells would form the core of a new, artificial reef. As wildlife discovered the calcium deposits, a natural reef would form. Over time, the city’s shaky foundations would become a stable reef ecosystem. Already, Armstrong and her group have had some success creating small-scale versions of the proto-cell reef in the lab, and they’re moving on to experiments in controlled natural areas.
If our cities do evolve to be more like biological organisms and ecosystems, it could change the way communities form within their walls. “We might start to experience the city as something we have to take care of the way we take care of our bodies,” Armstrong suggested. In a biological city, using toxic chemicals in your kitchen might cause your algae lights to die. “We’ll take more care of the city because we feel its injuries more deeply,” Armstrong said. It’s possible that this would generate a sense of collective responsibility for our buildings and avenues. Neighbors would tend their buildings together, trading recipes for making fuel the way people today trade recipes for holiday cakes.
Armstrong’s hyper-technological biometropolis shares something in common with Judith Layzer’s vision of small, slow cities devoted to farming. Both of them arise from the belief that city dwellers will become producers rather than consumers. With home bioreactors, Armstrong said, “our spaces will become a place where we can generate wealth.” This idea is central to the SPIN model of urban farming, too. “It’s about decentralizing energy and food production, basically,” Armstrong concluded. Of course, it’s impossible to predict what the consequences would be for people in cities whose buildings were half-alive. Armstrong is willing to admit her ideas are utopian, and that’s the point. “You need something to aim at,” she said with a smile.
As we look further to the future in the next part, we’ll be taking aim at something even more speculative than self-healing cities that look like glowing ruins and sprout food and power from every surface. We’ll see what humanity might become if we manage to survive for another million years. To do this we’re going to need to do more than rebuild our cities. We’ll need to rebuild the entire Earth. And then we’ll start striking out for the territories beyond our planet, lifting ourselves into space and colonizing the solar system. What will humans be like after tens of thousands of years of evolution, especially in space? It’s possible that our progeny will be as unlike us as we are from Australopithecus—and yet they will still be as human as our distant hominin ancestors were.
PART V THE MILLION-YEAR VIEW
19. TERRAFORMING EARTH
THE LONG-TERM GOAL for Homo sapiens as a species right now should be to survive for at least another million years. It’s not much to ask. As we know, a few species have survived for billions of years, and many have survived for tens of millions. Our ancient ancestors started exploring the world beyond Africa over a million years ago, and so it seems fitting to pick the next million years as the first distant horizon where we’ll set our sights. We’ve already talked about how we can start this journey by building cities that are safer and more sustainable. Eventually, however, we’re going to build cities on the Moon and other planets. Our future is among the stars, as the science-fiction author Octavia Butler suggests. But long before we have the technologies to get there, our survival will depend on looking at Earth from the perspective of extraterrestrials.
Imagine we’re on an interstellar voyage and we encounter an Earthlike planet. As we survey it from orbit, we discover that this planet is full of life, and covered with sprawling artificial structures built by a scientifically advanced civilization. Seeing those, most of us would say the planet is controlled by a group of intelligent beings. That’s the extraterrestrial perspective. Right now, we’re stuck in the terrestrial perspective, where we do not really regard ourselves as “controlling” the Earth. Nor do we see ourselves as one group. From space we might look like a unified civilization of clever monkeys who hang out together building towers, but down on Earth we are Russians, Nigerians, Brazilians, and many other identities that divide us. Our differences aren’t always a problem. But they have so far prevented us from coming up with a global solution to maintaining the Earth’s resources. We won’t make it into the far future unless we start banding together as a species to control the Earth in a way we never have before.
When I say “control the Earth,” I don’t mean that we’ll all shake our fists at the sky and declare ourselves masters of everything. As entertaining as that would be, I’m talking about something a bit less grandiose. We simply need to take responsibility for something that’s been true for centuries: Human beings control what happens to most ecosystems on the planet. We’re an invasive species, and we’ve turned wild prairies into farms,
deserts into cities, and oceans into shipping lanes studded with oil wells. There is also overwhelming evidence that our habit of burning fossil fuels has changed the molecular composition of the air we breathe, pushing us in the direction of a greenhouse planet. More than at any other time in history, humans control the environment. Still, our environment is going to change disastrously at some point, whether it’s heated by our carbon emissions from fossil fuels or cooled by megavolcano eruptions.
Our first priority in the near future must be to control our carbon output. I cannot emphasize this enough. As environmental writers like Bill McKibben and Mark Hertsgaard have argued, our fossil-fuel emissions are heating up the planet, and we can prevent this situation from becoming worse by using green sources of energy. Maggie Koerth-Baker points out in Before the Lights Go Out: Conquering the Energy Crisis Before It Conquers Us that we already have several types of sustainable energy to choose from, including solar and wind. Government representatives who attend the annual U.N. Climate Change Conferences are also coming up with strategies to encourage countries to curb fossil-fuel use, proposing everything from carbon taxes to emissions regulations.
The problem is that our climate has already been permanently changed for the next millennium, as the geobiologist Roger Summons explained in part one of this book. To prevent the planet from becoming uninhabitable, we’ll have to take our control of the environment a step further and become geoengineers, or people who use technology to shape geological processes. Though “geoengineering” is the proper term here, I used the word “terraforming” in the title of this chapter because it refers to making other planets more comfortable for humans. Earth has been many planets over its history. As geoengineers, we aren’t going to “heal” the Earth, or return it to a prehuman “state of nature.” That would mean submitting ourselves to the vicissitudes of the planet’s carbon cycles, which have already caused several mass extinctions. What we need to do is actually quite unnatural: we must prevent the Earth from going through its periodic transformation into a greenhouse that is inhospitable to humans and the food webs where we evolved. Put another way, we need to adapt the planet to suit humanity.
Over the coming centuries, we’ll need to take measures more drastic than cutting back on fossil-fuel use and ramping up the deployment of alternative energies. Eventually we’ll have to “hack the planet,” as they say in science-fiction movies. And we’ll do that in part by re-creating great planetary disasters from history.
Blocking the Sun
To make Earth more human-friendly, our geoengineering projects will need to cool the planet down and remove carbon dioxide from the atmosphere. These projects fall into two categories. The first, called solar management, would reduce the sunlight that warms the planet. The second, called carbon-dioxide removal, does exactly what it sounds like. Futurist Jamais Cascio, author of Hacking the Earth: Understanding the Consequences of Geoengineering, predicts that we’ll see an attempt to initiate a major geoengineering project in the next 10 years, and it will probably be solar management. “It’s a faster effect and tends to be relatively cheap, and some estimates are in the billion-dollar range,” he said. “It’s cheap enough that a small country or a rich guy with a hero complex who wants to save the world could do it.” Indeed, one solar-management project is already under way, albeit inadvertently. Evidence suggests that sulfur-laced aerosol exhaust emitted by cargo ships on the ocean changes the structure of high clouds, making them more reflective and possibly cooling temperatures over the water. Some solar-management plans take note of this discovery, and propose that we fill the oceans with ships spraying aerosols high into the air. But other strategies are more radical.
To find out how we’d shield our planet from sunlight, I visited the University of Oxford, winding my way through the city’s maze of pale gold spires and stone alleys to find an enclave of would-be geoengineers. Few deliberate geoengineering projects have been tried to date, but the mandate of the future-focused Oxford Martin School is to tackle scientific problems that will become important over the next century. The center is helping invent a field of science that doesn’t properly exist yet—but that will soon become critically important. One of its researchers is Simon Driscoll, a young geophysicist who divides his time between studying historic volcanic eruptions and figuring out how geoengineers could duplicate the effects of a volcano in the Earth’s atmosphere without actually blowing anything up.
Driscoll told me what volcanoes do to the atmosphere while cobbling together cups of tea in the cluttered atmospheric-physics department kitchen. Along with all the flaming lava, they emit tiny airborne particles called aerosols, which are trapped by the Earth’s atmosphere. He cupped his hands into a half sphere over the steam erupting from our mugs of tea, pantomiming the layers of Earth’s atmosphere trapping aerosols. Soot, sulfuric acid mixed with water, and other particles erupt from the volcano, shoot far above the breathable part of our atmosphere but remain hanging somewhere above the clouds, scattering solar radiation back into space. With less sunlight hitting the Earth’s surface, the climate cools. This is exactly what happened after the famous eruption of Krakatoa in the late 19th century. The eruption was so enormous that it sent sulfur-laced particles high into the stratosphere, a layer of atmosphere that sits between ten and forty-eight kilometers above the planet, where they reflected enough sunlight to lower global temperatures by 2.2 degrees Fahrenheit on average. The particles altered weather patterns for several years.
Driscoll drew a model of the upper atmosphere on a whiteboard. “Here’s the troposphere,” he said, drawing an arc. Above that he drew another arc for the tropopause, which sits between the troposphere and the next arc, the stratosphere. Most planes fly roughly in the upper troposphere, occasionally entering the stratosphere. To cool the planet, Driscoll explained, we’d want to inject reflective particles into the stratosphere, because it’s too high for rain to wash them out. These particles might remain floating in the stratosphere for up to two years, reflecting the light and preventing the sun from heating up the lower levels of the atmosphere, where we live. Driscoll’s passion is in creating computer models of how the climate has responded to past eruptions. He then uses those models to predict the outcomes of geoengineering projects.
The Harvard physicist and public-policy professor David Keith has suggested that we could engineer particles into tiny, thin discs with “self-levitating” properties that could help them remain in the stratosphere for over twenty years. “There’s a lot of talk about ‘particle X,’ or the optimal particle,” Driscoll said. “You want something that scatters light without absorbing it.” He added that some scientists have suggested using soot, a common volcanic by-product, because it could be self-levitating. The problem is that data from previous volcanic eruptions shows that soot absorbs low-wavelength light, which causes unexpected atmospheric effects. If past eruptions like Krakatoa are any indication—and they should be—massive soot injections would cool most of the planet, but changes in stratospheric winds would mean that the area over Eurasia’s valuable farmlands would get hotter. So the unintended consequences could actually make food security much worse.
It’s not clear how we’d accomplish the monumental task of injecting the particles, but Driscoll’s colleagues at Oxford believe we could release them from spigots attached to enormous weather balloons. Weather balloons typically fly in the stratosphere, and they could release reflective particles as a kind of cloud while remaining tethered to an ocean vessel. The stratosphere’s intense winds would carry the particles all around the globe. However, getting particles into the atmosphere isn’t the tough part.
The real issues, for Driscoll and his colleagues, are the unintended consequences of doping our atmosphere with substances normally unleashed during horrific catastrophes. Rutgers atmospheric scientist Alan Robock has run a number of computer simulations of the sulfate-particle injection process, and warns that it could destroy familiar weather patterns, erode the ozone layer,
and hasten the process of ocean acidification, a major cause of extinctions.
“I think a lot about the doomsday things that might happen,” Driscoll said. Unintended warming and acidification are two possibilities, but geoengineering could also “shut down monsoons,” he speculated. There are limits to what we can predict, however. We’ve never done anything like this before.
If the planet starts heating up rapidly, and droughts are causing mass death, it’s very possible that we’ll become desperate enough to try solar management. The planet would rapidly cool a few degrees, and give crops a chance to thrive again. What will it be like to live through a geoengineering project like that? “People say we’ll have white skies—blue skies will be a thing of the past,” Cascio said. Plus, solar management is only “a tourniquet,” he warned. The greater injury would still need treating. We might cut the heat, but we’d still be coping with elevated levels of carbon in our atmosphere, interacting with sunlight to raise temperatures. When the reflective particles precipitated out of the stratosphere the planet would once again undergo rapid, intense heating. “You could make things significantly worse if you’re not pulling carbon down at the same time,” Cascio said. That’s why we need a way of removing carbon from the atmosphere while we’re blocking the sun.
Turning Earth into a Carbon-Eating Machine
One of the only geoengineering efforts ever tried was aimed at pulling carbon out of the atmosphere using one of the Earth’s most adaptable organisms: algae called diatoms. Researchers have suggested that we could scrub the atmosphere by re-creating the conditions that created our oxygen-rich atmosphere in the first place. In several experiments, geoengineers fertilized patches of the Southern Sea with powdered iron, creating a feast for local algae. This resulted in enormous algae blooms. The scientists’ hope was that the single-celled organisms could pull carbon out of the air as part of their natural life cycle, sequestering the unwanted molecules in their bodies and releasing oxygen in its place. As the algae died, they would fall to the ocean bottom, taking the carbon with them. During many of the experiments, however, the diatoms released carbon back into the atmosphere when they died instead of transporting it into the deep ocean. Still, a few experiments suggested that carbon-saturated algae can sink to the ocean floor under the right conditions. More recently, an entrepreneur conducted a rogue geoengineering project of this type off the coast of Canada. The diatoms bloomed, but the jury is still out on whether ocean fertilization is a viable option.
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