Editor’s note: Welcome to Grist’s presentation of Alex Steffen’s new book Carbon Zero. We’ll be posting a new chapter every day till we’re done — here’s the full table of contents. And this post will tell you a little more about the project. If you like what you read, you can order Carbon Zero from Amazon.

Sustenance: Bringing cities and nature together

Everything in the human world originates in nature: Everything around us is made of parts that are either mined or grown. Most of our attention, when it comes to climate, is on the mined — particularly on the effects of burning mined fossil fuels, like coal, oil, and gas. And these fossil-fuel emissions are by far the biggest danger we face, and so focusing on them makes sense.

Yet dirty energy is not the only source of greenhouse gases. Other climate emissions are created when we grow things. Still others arise from our management of ecosystems we more traditionally think of as wild. Unless we treat natural systems wisely, we won’t be able to reduce emissions to the levels we must; and ultimately, cities offer a lever for change that at first might seem counterintuitive. That’s because urban economies dictate how the natural world is turned into the human world, and whether that transformation becomes sustainable, or not.

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Food and climate change

To discuss the ways cities and nature are linked — and why changing urbanites’ relationships with natural places could help lower a city’s carbon footprint — the best place to start is with food.

Feeding our cities is a less important source of greenhouse gases than transportation, building, and consumption; paradoxically, though, changing our food systems could offer profound reductions in emissions. That’s because, done right, agriculture, fishing, and forestry could change from being destructive practices to being vehicles for atmospheric restoration.

Most of the time, when the subject of food comes up in the context of climate change, consensus about the nature of the problem is hard to come by. Many people are simply unaware that what we eat has any climate impacts at all. Some dramatically overstate the importance of agriculture in a developed-world city’s climate emissions, claiming that one-fourth, one-third, or even one-half of all emissions come from agriculture (for U.S. cities the real portion of emissions coming from food systems seems to average around 13 percent). Others acknowledge that agriculture has impacts, but essentially believe that since we all have to eat, there’s little we can do. Only a few have more nuanced views.

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Similarly, when solutions are brought up, hostile camps immediately emerge. Some focus on what we eat, insisting that dropping our consumption of animal products and overprocessed fast food is the only step to consider. (Eating less red meat and emphasizing lightly processed foods would definitely have a beneficial impact on our emissions. It would also certainly have real health benefits — and America’s obesity epidemic is more than just a human tragedy, it’s a climate problem, as we saw in chapter 3.) Others focus on where our food comes from, advocating locally grown food. Others look at the problem as centered on the food itself, and discuss ideas for reinventing food, such as developing lab-grown meat and genetically engineered algal proteins, establishing industrial aquaculture, and using smart-breeding programs to produce more efficient crops. Others, still, look at the nature of industrial agriculture, and the massive chemical and energy inputs it demands to produce food, and say the answer must start with a turn to smaller farms, fewer inputs, and better farming techniques.

All of these views are right. All of them also suffer from little-discussed limitations. And all of them, to my mind, overlook the most important fact about food: It is the by-product of ecosystems, and an intimate connection between our bodies and the workings of those ecosystems. To talk about food and climate is ultimately to speak of cities and nature, and how to bring them back together.

Farming and ecosystems

Essentially all the food we eat is created by natural systems, directly or indirectly. Even the most engineered, miles-wide agribusiness farm, growing one genetically altered variety of corn in vast fields, drenched in pesticides and fertilizers, worked by a few men and women in enormous machines — even that farm is nature. The crops on that farm grow in living soils built out of minerals, previous plant life, and an abundance of microorganisms. The planet’s water cycle produced the rains that water the furrows (even when that water is “fossil water” pumped from deep aquifers). Bees or other insects pollinated the plants. The sun provided the energy for photosynthesis, filtered by an ozone layer, which is itself a product of the oxygen plants release. The carbon cycle of the planet’s oceans and forests kept the weather generally stable. The genes in the corn itself came not just from breeding, but also from nature, part of the planet’s biodiversity. Even the most ruthlessly artificial landscape maintains its fertility only by drawing on nature’s bounty.

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Bad farming can be described simply as farming that destroys more of that bounty than it gives back. Bad farming also tends to be climate-damaging farming. Some of the bad practices are matters of scale — the energy costs of working gigantic farms and far-flung distribution systems at a substantial profit; some are matters of trying to maintain monocultures and predictable crops in a world where both are gnawed on constantly by entropy; some are simply a matter of not caring very much about the future; many are the products of (and, in return, the generators of) the financial desperation of the farmers themselves.

There is a scientific term for the bounty of nature on which all farming depends: ecosystem services. And these ecosystem services are not minor matters. An international network of scientists estimated that the monetary value humans get from the ecosystem services that maintain civilization is at least $33 trillion a year. That’s 33,000 billions of dollars. But even that vast sum (equal to roughly half of the value created by entire human economy each year) is ridiculously low if we try to measure the replacement value of ecosystem services, because in many cases we simply don’t know how to replicate an essential service (say pollination) at any price. We don’t know how to remake the planet at will. We are, at best, gardeners: changing, choosing, working by necessity with a certain “watchful humility,” understanding that sometimes all we can do is nudge and encourage. We think we run the game, but all of our chemical expertise and engineering power only tilt the odds in our favor; they don’t change the rules. We still live off nature’s bounty, and bad farming erodes that bounty season after season.


Better farming is the beginning of climate sanity. We know that it is possible to farm at more varied scales — with some old wisdom and new techniques, fewer chemical inputs, and greater embrace of more diverse crops and varied results — and produce better food with a lower carbon footprint. We also know that within the mad system of subsidies and unpaid externalities (externalities are costs a practice imposes on others) that dominates American agriculture, sustainable food costs more, while destructive food sells cheap.

The fast-growing local food movement includes many people who are willing to pay higher prices for food that reflects their values. Supporting good food wherever it’s grown is an excellent plan — for those who can afford the premium. The “local” part is a little trickier. Despite widespread discussion of “food miles,” the evidence seems to be pretty conclusive that the energy spent transporting food from distant farms is a small fraction of the total energy budget (and thus emissions) of that food. The difference in shipping something 1,000 miles and shipping it 100 miles is not profound; and that difference is often dwarfed many times over by the emissions a person generates if he or she drives to the store to buy that food.

Nonetheless, I think supporting local food is vital, for reasons that have nothing to do with how much diesel got burned trucking our lettuce to the supermarket, and everything to do with the quality of our “foodsheds” — the network of places from where our food comes. For most of us, our foodsheds are stretched across the planet to distant, little-known places we might not even be able to find on Google Maps. But we can also think of “local foodsheds.” Some people define these as all the farms and forests and fisheries and pastures within a set area, like a 100-mile radius, of wherever their products are currently shipped. But perhaps a more useful definition is: all the places that provide our food, which are also directly connected to the ecosystems that surround our cities — all the farms that drain into our local rivers, lakes, or bays (and the ones that drain into the watershed where we get our drinking water), for instance. Or, all the forests that help keep those waters flowing. Or, all the places that have a similar set of native species as the ones we might have found where we live. Different ways to slice it, all valid, and all pointing towards the same idea: We want the natural systems around us to grow healthier, and growing good food can be a way of nurturing that health.

Making our foodsheds healthy and resilient shows an engagement with long-term preparedness at its most basic. It would not be unwise for a metro region to have enough good farmers on enough good land in its region for it to feed itself (even if, in the foreseeable future, food systems are likely to remain global and trade-based). Explicit strategies to preserve farmland, create green belts, support farm families with good prices and farm capacities with good regional agricultural infrastructure (from processing plants to slaughterhouses) can lead to a region with a strong farm economy — and a deeply rugged regional food supply. This is important enough that cities ought to have people thinking about and working on food supply and city-country relationships, both within government and in the civic sphere.

We need a lot of market innovations for connecting people to surrounding ecosystems through foodsheds as well, but there are some great existing practices to build on. A strong market for sustainably grown produce can encourage farmers all over the region to invest in new, more sustainable practices. Steady support for small farmers (for example, through subscriptions to community-supported agriculture programs that connect us directly with a farmer) and farmland preservation can keep the farm belts around our cities growing crops rather than sprouting “McManors” (McMansions on what once were working farms). Supporting sustainable forestry at the lumber store, sustainable fibers at the clothing store, and sustainable fisheries at the market, can help reinforce good practices in forests, meadows, and rivers. Finally, supporting good policies — policies that reward good stewardship and punish ecosystem degradation — can help lower emissions.

How? There are a variety of farming practices that can reduce the greenhouse gases released in the growing of our food, from better tilling to “digesters” that turn animal waste into fertilizer while capturing the methane released in the process, which can then be burned as fuel. (Methane is a potent greenhouse gas, but comparatively harmless when burned.) Distribution practices can change — delivering food directly from farms to homes is much more energy-efficient than sending crops to distribution warehouses, shipping them to stores, and then having people drive to the store to buy them. Food waste can be reduced and food processing made less energy-intensive (or even less necessary).

Green infrastructure

Better practices on the farm only reweave one part of a region’s ecological tapestry, though. To really make a difference, we need to weave the whole working landscape together with wild systems, nurturing a healthier, hybrid ecosystem. A properly cared-for ecosystem grows more capable of buffering us against climate extremes as it heals. It also offers the potential of soaking up carbon dioxide already in the air as it matures. Foodsheds are our windows into that integration of human and wild. In places with relatively healthy and intact foodsheds, much is possible.

That includes the potential of weaving cities themselves back into the natural tapestry. Nature doesn’t stop at the city limits, after all. Our cities themselves are natural systems (though, admittedly, of a strange kind), and those natural systems can be designed to minimize the ecological impacts of our lives.

One approach: building “green infrastructure.” Green infrastructure usually refers to urban systems designed to treat waste flows (usually storm water, wastewater, or organic waste) and turn them into something useful by running them through systems that mimic natural processes. Sometimes these systems look natural — many integrate greenery into their operation with plants and trees and mosses everywhere — but they don’t have to. What is ultimately most important is not the leaves above but the systems below.

District-level green infrastructure systems can also appeal to our innate sense of biophilia by surrounding us with life. Enough street trees planted to soak up rainwater and shade sidewalks in summer create over time an urban forest, adding a sense of leafy quiet to dense neighborhoods and giving us the wonderful feeling of walking in green cathedrals of old trees, while the view from apartment windows becomes dappled light and leaves. The air smells cleaner. Swales and rain gardens and collecting ponds reconnect us to water and the seasons. (If we get bold enough about combining green infrastructure with stricter water pollution laws, even some of our most-polluted urban rivers, lakes, and bays can actually become swimmable and fishable again within a few decades. Think about what it says that they’re not.) Small vegetable gardens give us a place to put our hands in the dirt and experience the satisfaction of eating food we’ve grown, and perhaps returning our compost directly to the soil again, feeling the whole cycle of food and life. Living in compact communities woven through with trees and gardens and running water gives us the chance to feel connected with natural flows even when we’re a long way from any wilderness.

But wait a minute, you might think. How can we have both density and green space in the same city? And, if you took the current allocation of urban land for granted, you’d be right to ask: In most cities right now density and green space are locked in a zero-sum game, and most of the time in a carbon zero city, density has to win.

Why would we take anything like that for granted, though, when our cities are home to vast acreages of extra land? I’m referring, of course, to the asphalt.

Roads and parking lots make up a gigantic portion of the surface area of most North American cities. For instance, though no official figure exists, planners I asked estimate that 40 percent or more of Seattle’s total area is roads, parking spaces, and auto-oriented infrastructure — and that’s likely on the low side of the national average. In even the densest North American cities, thousands of acres are covered with parking lots and parking spaces; thousands more are taken up by roads that are likely not the highest, best use of the public land they occupy.

If we succeed in the kind of “mode-shift” I discussed in the Urbanism chapter — if larger numbers of people choose walkable neighborhoods that are well served by transit and either use their cars less or give them up completely — we could reclaim many sparsely used roads for better uses. Some streets we might convert wholesale. Some we might want to shave a lane or two off of. Some major streets will always be in heavy demand, of course, and will need to be maintained well for heavy use. Most cities will find, though, that they have a large pavement surplus, if they’re brave enough to use it. (In fact, not only will most cities find they have a pavement surplus in the future, most already do now.)

We can afford to plow up the pavement. The money is there in budgets currently spent maintaining and upgrading roads. Some green infrastructure, thoughtfully designed, fits perfectly the needs of pedestrians, bicyclists, and transit-riders, so newly designed streets can often meet the needs of both storm water and strollers. Though I don’t know of any comprehensive studies on the subject, I’d think the smart bet is that green infrastructure and pedestrian- and transit-focused streets are significantly cheaper to maintain than a comparable amount of large-scale infrastructure and roadway would be. What is certain, though, is that people like to live in lush, green neighborhoods. Homes shaded by large trees or facing parks routinely command higher prices than houses surrounded only by lawn, asphalt, and concrete.

Cities and soil

Discussing biological waste demands a certain amount of discretion. While most of us are happy to hear about the composting of yard waste and food scraps, many of us get uncomfortable when we discuss industrial biological waste, and downright squeamish when the subject turns to human waste.

The fact is, though, that all biological waste is soil, temporarily transformed. And we now have more ability than ever to complete the transformation again, turning waste back into soil. Various biodigesters, industrial composters, and other systems exist to do the job, and with the rapid spread of cheap biosensors, health and safety is much less an issue than it was when our ancestors started deploying the old systems we now use (many of our systems date back a hundred years or more; some have their deepest roots in Roman engineering).

Those old systems practically demand innovation. Though early pioneers have done amazing work proving the feasibility of some new approaches to managing organic wastes, there is no doubt that plenty of room for improvement awaits. This is true for the engineering of the systems themselves, the biology of the life within and around them, the design that makes them part of the urban landscape, the policies that regulate them, and even the financing that builds them — opportunities for innovation, right across the board.

One critical task, best, in my opinion, begun close to home, is repurposing our waste as a resource for regional ecosystem restoration. Every year, a large city sends thousands of tons of food scraps and yard waste to the landfill; treats rivers of sewage with toxic chemicals, straining and dumping the solids in waste deposits (or burning them in a giant incinerator, or just leaving the “clean” sludge to flow into a nearby body of water); and carts off massive amounts of construction and demolition waste. These waste streams represent vast flows of organic nutrients, biomass, and potential “clean fill” (stuff that can be used to fill holes, raise hills, and create dikes and levees).

Everything that flows into our cities that is not a toxic chemical ought to be reclaimed and used to promote regional health. Unfortunately, much of it is mixed with toxic chemicals along the way, or treated in ways that make it less useful or more dangerous. Sewage solids, for instance: Though people have used human manure as fertilizer for millennia, and we know how to handle it safely, our poo these days is often mixed with all manner of pharmaceuticals, household chemicals, and other nasty stuff. That limits its use to places where people and fragile ecosystems won’t be exposed to the dangers it poses, or where the ecological benefits of using the nutrients simply outweigh the risks. Putting these nutrients to use often just makes good ecological sense, especially when we consider that most of our storage and treatment options today actually release all the same toxics back into our ecosystem anyway — just in unplanned and haphazard ways (like the massive releases of nitrogen that are creating ocean dead zones at the outflows of most of our rivers). If we work carefully, we gain a gigantic source of fertile soil.

It’s hard for many of us to grasp how much opportunity there is in most places to restore soils, and thus ecosystems. The last 100 years have seen massive clear-cutting of forests, abandonment of farms, erosion of soils, poisoning of streams and lakes, and just general mayhem across the landscape. Much of North America is neglected at best. Quite a bit of it is in a state of slow collapse and growing vulnerability to the stresses and storms of shifting climates. Millions of acres that look green from the window of a jet flying 30,000 feet above ought to be in the ecological equivalent of intensive care.

We’d like to think that no such places exist, that every piece of countryside is too precious and pristine to fertilize with mildly toxic poo, but that’s just not the reality. Scattered all through our rural areas we can find devastated landscapes: polluted soils and dead lakes; once-fertile farmlands that have been scrapped and paved and built over with now-abandoned subdivisions and parking lots; hillsides where over-cutting of trees or strip-mining or careless farming has washed away the soil, until all that remains is a scrub of weeds on a rocky desert. These are all places that need profound interventions. They are not places that will recover if just left alone (at least not in human time-scales). They demand restoration on a scale we might almost consider terraforming (the creation of Earth-like environments where they do not now exist).

City systems that work more like nature promise, perhaps, the restoration of the parts of the natural tapestry that are most worn and torn. It is quite possibly within our capacities today to plant poisoned landscapes with bioremediating shrubs and trees that will gradually accumulate the toxins and heavy metals in the soil and water, concentrating them so they can be safely stored (or possibly reused in future industry, should the needed processes become available). Fertilizing a forest of such detoxifying plants with “biosolids” (human fertilizer) may well be a huge improvement in ecosystem health. Likewise, denuded slopes could be reforested, native plant nurseries created, and biomass farms (like bamboo plantations) fed. It seems to me we must find ways of doing this in which the risk is far outweighed by the ability to restore larger flows to health in the extremely rapid time frames in which we must act. Of course, seen in this light, using completely safe resources — like composted kitchen scraps as farm fertilizer — is a no-brainer. Our most problematic wastes demand we think more carefully, discovering new ways of working with nature, or simply ending the production of those wastes if they are simply irredeemable. Within decades we’ll need to stop washing those wastes away, because on a finite planet, there is no “away.” We live wallowing in the poisons and pollution we create.

By restoring the tapestry of natural systems, and reconnecting urban nutrients with natural cycles, we also gain a powerful way of balancing some of the harm we’ve already done: carbon sequestration. Forests and other healthy ecosystems contain vast amounts of carbon dioxide “locked up” in tree trunks, plants, and soils. Climate scientist Jim Hansen estimates that 20 percent of greenhouse gases now in the atmosphere come from centuries of deforestation (which, unfortunately, is at a crescendo today, with enormous tracts of rainforest being cleared and burned). But to a large degree, that process is reversible. We can plant forests (or engage in “afforestation”) and as those trees grow, they will lock up carbon dioxide currently in the air.

How much carbon could we take out of the atmosphere? In a 2011 paper, Hansen and his coauthors estimated that reforestation might offer the possibility of sequestering as much as 100 gigatons of atmospheric CO2 this century (that’s a lot). This ability to pull carbon dioxide we’ve already emitted out of the air by recreating the millions of acres of forests that covered the earth at the beginning of the last century is the best reason we have to believe that we can come back down to 350 ppm after we peak our emissions. Regrow Earth’s forests, and we can run the “carbon meter” backwards to a certain extent.

Those new “carbon forests” can also help fill in the gaps in the natural tapestry, making the systems around them stronger and more resilient. Indeed, restoring damaged lands around critical wild lands can help buffer those wild places from the disruptions we know climate chaos is causing. And, as these new forests mature, we can even imagine expertise in the craft of feraculture (the gardening of wilderness) emerging quickly (though none too soon).

So replanting the world’s woods is a pressing global task, and every region ought to be thinking about how to restore as many forests as it can within ecological sense and economic realities. Indeed, business models for afforestation that locks CO2 into tree trunks, provides ecosystem services, and supports threatened biodiversity, present maybe the most glaring unfilled solution space in North America.

But tree-planting is not the only way to pull carbon out of the atmosphere. It looks like fast-growing woody weeds will work, too. The reason? Biochar. If we grow and harvest those shrubs, we can char them so we can get energy from them (usually as “gasified” biofuels) while most of their carbon is kept bound in the charred leftovers. If we then dig that charcoal back into the soil, it enriches that soil while sequestering the CO2 (potentially for centuries, if done right). This raises the possibility that completely devastated landscapes around our cities could be transformed from wastelands to sequestration farms, fertilized with biosolids, creating energy and improving soils year after year while reducing emissions. Over time, these places could actually grow back into thriving forests. Our great-great-grandchildren might never know that these areas were once just barrens and patches of grass crowding up through old cracked asphalt and abandoned subdivisions.

If we both grew serious about our efforts to use metro waste to restore and reclaim our region’s hardest hit lands, and invested in good farming throughout our cities’ foodsheds, we could help change rural lands from carbon sources to carbon sinks. In the process, we might help struggling rural economies find new futures for themselves. We could see success all around.

But rural restoration and good farming aren’t magic. There’s no way the emissions reductions they offer could offset an entire city that went along unchanged. But that said, it looks entirely within the realm of possibility that a city could collaborate with its surrounding region in efforts that offset some or all of the emissions it might still release after it densifies into people-focused communities, rebuilds its buildings to be super-efficient, establishes district solutions for energy and water, and redesigns its consumption along 21st-century lines. Better relationships with nature will never offer us a free pass to continue with business as usual; however, they could help us close the gaps left even after we achieve major cuts in energy use.

Restoration as ruggedization

Finally, taking responsibility for our regional ecosystems can help us meet another critical task: that of ruggedizing our cities to withstand chaos.

For whatever else the century ahead of us brings, it will certainly bring all manner of chaos. Climate change we have already set in motion is producing strange weather shifts, extreme droughts and flooding rains, large storms and surging seas. (Un)natural disasters can interrupt the flow of goods (like the unrelated Japanese nuclear crisis did for electronics components), lead to crop failures and food shortages (as happened two years ago when Russia, after the worst heat waves and wildfires in its history, banned the export of grain), and provoke conflict and unrest (as has happened already in numerous countries where resources are depleting, like Haiti and Rwanda). Epidemic diseases will spread. Global systems upon which we depend will strain under the weight. And all of these stresses will come more frequently, somewhat unpredictably, and often unfairly.

Even in prosperous countries, it may not be prudent to expect the kind of disaster and recovery aid we’re used to thinking of being available. Especially when an entire region is hit with a serious problem — say, a megaquake jolts the entire West Coast of the U.S., or wildfires run out of control the length of the Rockies, or torrential rains flood cities and towns all along the Mississippi, or one of the super-hurricanes some scientists are warning of brings havoc to the Gulf Coast — there won’t be sufficient resources and capacities for the federal government to help everyone who needs it, or to restore everything back to the way it was once the crisis ends. And if we end up with large-scale disasters following one after another, we may well end up needing to look after ourselves. In those cases, the cavalry ain’t coming.

Furthermore, disasters cause emissions. We tend not to think of things this way, but every time something is destroyed and then replaced before it needed to be (or where it might not have needed to be replaced at all), greenhouse gases are pointlessly emitted. Not to mention the emissions caused by wildfires and the like. Large, frequent disasters mean lots of pointless emissions. Avoiding disaster, then, is an emissions-reduction strategy.

All of this means we need to focus on two critical goals: survivability and ruggedization.

Survivability means safety and security and the capacity to be productive and proactive, even in times of crisis. Survivability for cities is enhanced by systems that are less vulnerable and more resilient in the face of chaos. It is reinforced by the reduction of base demands, minimizing the inputs cities need in order to run. Put more simply, if your city can withstand some hard knocks and keep going even when supplies run short, you’re going to be much better off. If you live in a place that has put some thought into safety, security, and continuity in times of crisis, it then becomes reasonable to work with your neighbors and prepare your family to build robust survivability into your life. Its basic components are:

  • Systems designed to prove less likely to break under strain. That might be because they’re networked systems of simple parts, like district energy systems; because they’re designed with a certain amount of redundancy and flexibility, like the Internet itself; or because they are within the direct control of the users (like local tool libraries), and therefore not as vulnerable to shortages caused by organizational breakdowns. Smart infrastructure and home systems designed to deliver optimized benefits for emissions reductions can often deliver survivability benefits, too.
  • Patterns of living that don’t need a lot of resources to keep running. For instance, in an emergency, a Passivhaus building can be kept livable without central heat. Similarly, a neighborhood built for bicycling and walking can remain mobile even if fuel supplies are interrupted. Reducing a city’s vulnerability to resource disruption is a little-spoken-of but potentially major benefit of a carbon zero strategy, and can strongly reinforce community and individual efforts.
  • As many citizens as possible possess control over life-and-death basics — they have a month or more of basic food supplies stored, they have emergency supplies like first-aid kits and flashlights, they have training in emergency responses — and at least a minimal level of emotional resilience built up through friendships and neighborly ties (so that people are ready to help each other, look out for the vulnerable, work together, and fend off problematic interlopers). Desperate people do terrible things. It is in everyone’s interest to avoid creating desperation.

Ruggedization is more important still. In a ruggedized city, the larger systems that keep a city operable do not fail even under extreme conditions. Ruggedization is the proactive avoidance of collapse.

The first condition of ruggedization is that vital systems are not placed in brittle contexts. You don’t want the city’s only aqueduct built in a place where it’s vulnerable to earthquakes, or its trauma center hospital built in a flood plain, or its emergency responders and police officers living far away when transportation systems could fail. Foreseeable disasters should be anticipated and avoided.

The second condition of ruggedization is that natural places and ecosystem services should be employed to make failures of vital systems less likely. Ecologists and engineers had been calling for the restoration of wetlands in the Mississippi Delta for almost 30 years before Hurricane Katrina hit New Orleans, and there is evidence that a healthier delta could have slowed storm surges and taken pressure off the levees protecting low-lying New Orleans neighborhoods, perhaps even preventing one of the nation’s worst “natural” disasters.

Restored ecosystems and ecosystem services can help prevent or reduce flooding and coastal storm surges, mitigate some of the effects of drought, lessen vulnerability to wildfires, resist onslaughts of invasive species, even prevent soil erosion and landslides. A city that wants to be tough in the face of disasters will be buffered by natural systems that are, themselves, rugged.

The third condition is that it breaks hard and repairs easy. Foresighted cities invest in the ruggedization of key systems, making them less likely to fail, even under absurdly difficult conditions. (This is especially true where the cost of even a single prolonged failure can easily outweigh the investment needed in ruggedization. For instance, having a 911 call center that becomes too hot to work in when a record heat wave hits will almost certainly cost more than building a better-designed call center in the first place.) Rugged cities also have the capacity to repair themselves: This runs from the most complex tasks, like quickly restoring safe water in a compromised urban system (by having emergency plans and workers trained to implement them, for example), to the simplest ones, like being able to provide critical replacement parts quickly and locally (by having strong distributed manufacturing capabilities, for instance).

The economic benefits of survivability

All this costs money, but funds invested in survivability and ruggedization can, potentially, pay themselves back many times over. It is important to remember that system failures are often incredibly costly; societal breakdowns caused by grim necessity and fear are economically ruinous. The economic losses suffered because of Katrina are certainly many times the cost that would have been required to restore the Mississippi Delta; and that restoration would have left us not with a still-wounded city and degraded surrounding nature, but with a thriving ecosystem.

Cities that begin to act now to ruggedize will reap economic benefits. For one thing, they’ll benefit by being more insurable than they would otherwise be. Reinsurance companies have already signaled that certain kinds of development in certain places will soon no longer be insurable at normal rates; and as costs mount from climate change and other planetary strains, business as usual will almost certainly become much more expensive to insure. Cities with many places and systems at risk may actually become effectively uninsurable.

That may not seem like a big deal, but remember that a local government’s ability to get low-cost credit to pay for the work it needs to do is tied directly to perceived risk, and that risk is measured in part by insurability. If the giant reinsurance companies say your town is poised on the edge of disaster, and refuse to back insurance there, businesses are likely to avoid it, some of the most mobile citizens will leave, and your town is in for some serious economic hard times.

On an even more somber note, ruggedized cities with survivable communities are far better positioned to thrive within prolonged megacrises. While I think betting on apocalyptic collapse is an unwise and perhaps unethical position to take, the facts are that some very serious, responsible institutions (like national militaries, scientific academies, reinsurance agencies, and intergovernmental financial bodies) warn that we are vulnerable to large-scale, widespread disruptions, potentially of extremely dire magnitudes.

It’s worth remembering that long, slow effects are often more difficult to mobilize against than sudden, dramatic catastrophes. With that said, smart cities should be preparing themselves for a variety of scenarios. That includes having at least thought through responses to climate-related disasters.

The absolutely wrong approach to take is trying to relocalize everything and imagine our small communities as fortresses of isolation in a landscape of chaos. Survivalism and separatism do not have good track records in history. Even in the worst-case scenarios, living in a dynamic and innovative city is a better survival strategy than any other that people of regular means have available to them (if you can afford a remote island, an extensive self-sufficiency setup, and a private army, that’s a different story).

Our goals ought to be to ruggedize our own cities and push as many of the wider political and economic systems in which we participate towards resilience and sustainability. Indeed, places that are pushing hard for change will, I believe, be the most prosperous places to be in good times, and the safest in bad times.

Read on: Conclusion: There’s still time if you act now

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