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 for a week — 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.


On Monday the 29th of October, 2012, a tidal surge 13.9 feet high (the highest ever recorded) washed up and over the waterfront in Lower Manhattan, pushed forward by the superstorm Sandy. That same week, the storm destroyed large swathes of coastline from the New Jersey shore to Fire Island, while driving torrential rains, heavy snows, and powerful winds inland across the eastern U.S. and Canada. By the time the storm blew out, it had killed more than 100 Americans, made thousands homeless, left millions without power, and caused at least $50 billion in damage. Sandy was, by any reckoning, one of the worst natural disasters in American history.

Maybe, though, the word “natural” belongs in quotes. Because what was surprising about Sandy wasn’t that it happened (indeed, many had predicted that rising sea levels and storms intensified by warmer oceans would make something like Sandy inevitable), but that it was seen so clearly, and so immediately, for what it was: a forewarning of what a planet in climate chaos has in store for us.

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Sandy was far from the first sign that climate change is here — scientists have been warning for decades of the dangers of a heating planet, and in the last 10 years we’ve seen a flurry of unprecedented storms, droughts, floods, melting glaciers, and wildfires, as well as record-breaking heat waves following one after another. Sandy, though, knocked down walls of denial and inattention that have kept us from admitting what’s happening to our world.

What’s happening is that we’re losing the climate fight. Climate change is here, it’s worsening quickly, its effects are more dire than many thought they would be, and — if we continue with business as usual — we’re on a track to unleash an almost unimaginable catastrophe on ourselves, our children, and our descendants.

“Part of learning from [Sandy] is the recognition that climate change is a reality,” said New York Gov. Andrew Cuomo at the time. “Extreme weather is a reality. It is a reality that we are vulnerable.” He added later, ”Anyone who says there is not a dramatic change in weather patterns is denying reality.”

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Our choice: “extremely dangerous” or “catastrophic”

To not warm the planet at all no longer remains an option. The Earth is already dangerously hotter than it was before the Industrial Revolution.

We used to think that warming up to 2 degrees C fell within a sort of “safe zone,” where we could expect change but not crisis. But in a world we’ve warmed only by about 1 degree C above the historical baseline, we’re already seeing massive climate impacts across the planet. These unexpected impacts, along with new projections from ever-improving climate models, tell us that the climate is not nearly as forgiving as we’d like it to be. As the Tyndall Center for Climate Change Research’s Kevin Anderson puts it, “1 degree is the new 2 degrees.” Two degrees, meanwhile, now appears not just dangerous, but extremely dangerous.

That means the menu of choices in front of us no longer includes a completely safe and stable climate. Instead, our choices come down to two options: a world in which climate change becomes extremely dangerous, or one in which it becomes totally catastrophic.

To keep climate change within that merely “extremely dangerous” range, scientists say, we must limit the rise in global temperatures to 2 degrees C. Allowing warming to accelerate beyond 2 degrees C to 4 degrees C takes us beyond extremely dangerous into downright insane.

Yet that’s where our current emissions trajectory is leading us: to a world 4 degrees C hotter, perhaps as soon as 2050; and perhaps even 6 degrees C hotter by the end of the century. Four degrees global temperature rise involves so many utterly catastrophic impacts — permanent droughts, large-scale shifts in agriculture, megastorms, rapid sea-level rise, ecosystem collapses, and so on (all triggering social instabilities) — that we can’t expect our global civilization to avoid serious disruptions, and in many places, long-term ruin. A world 4 degrees C hotter is, as some put it, “beyond adaption.” (A world 6 degrees C hotter is almost beyond comprehension: To conceive of a world 6 degrees warmer, imagine alligators in the Arctic.)

A world that’s 4 degrees C hotter would also be vulnerable to nonlinear climate feedbacks — ways in which the effects of warming (like the melting of the Arctic permafrost) could rapidly worsen warming itself (by, in this case, releasing enormous volumes of CO2 and methane now trapped in frozen soils). Some worry these feedbacks could lead to “runaway” climate change, wherein a cycle of warming and greenhouse-gas releases and more warming spirals viciously out of control. At that point, even the wildest “geoengineering” ideas — for example, creating artificial volcanoes to fill the stratosphere with sulfate particles, blocking some of the sunshine headed towards Earth — would be, at best, “Hail Mary” strategies (and would do nothing to address other catastrophic effects of rising emissions, like the acidification of the oceans and the resulting mass die-offs of ocean life). Spiraling climate chaos of this severity would leave us on a profoundly different planet than the Earth we now call home.

There is simply no way to put a cost to those kinds of impacts: Their magnitude transcends economic reckoning, because their impact could be greater than the entire human economy is worth. Four degrees of warming, Anderson and many others say, is therefore something we should avoid literally at all costs, because no economic cost we pay will be greater than the losses we risk in a climate catastrophe of that magnitude.

Now, all of this is the sort of thing that can bum you right the hell out, and it’s not irrational to let it get to you — there’s a real chance we may destroy civilization and much of the natural world in the decades ahead, and that’s a valid reason for being a bit glum. There’s just no shiny side to extreme climate chaos.

It’s not too late to avoid catastrophe

If that were the end of the story we could all just start drinking now. Hell, I’d buy the first round. But it’s not. We still have a choice. We still, just barely, have the option of choosing to limit warming to 2 degrees and then working hard to restore the climate once we’ve stabilized it. We can, yet, pause at “extremely dangerous” and pull back from the brink of chaos.

To do that, we have to limit the total amount of carbon dioxide and other greenhouse gases in the atmosphere. What’s the limit? Drawing on the scientific consensus, 350.org, the world’s leading climate advocacy network, puts the number at 565 more gigatons of CO2 (or about 450 parts-per-million [ppm] of CO2 in the atmosphere). That’s the most humanity can emit and still, probably, hold global warming to 2 degrees C.

That means we need to face a fact almost no one likes to discuss: We need to hit zero. That is, we need, as a species, to bring our global climate emissions into balance with what nature can safely absorb (actually, because we need to start rolling greenhouse gas concentrations backwards, we almost certainly need to emit less than nature can absorb, in order to take CO2 back out of the atmosphere and get back to safer greenhouse gas levels, of 350 ppm or less — but one shocking reality at a time is enough). This means that all the expressions of commitment we’ve heard from politicians about reducing greenhouse gas emissions by 50 percent off 1990 levels, say, or 80 percent by 2050 or whatever — all of those numbers are meaningless. The meaningful number is simple: zero, as soon as possible.

Zero, worldwide

A worldwide transition to a climate-balanced global economy (one which adds zero CO2 each year to the total CO2 in the atmosphere) lies completely within our reach. But to achieve it, we’ll need to be honest with ourselves about geopolitics and reality. Because we have some tough decisions to make.

Climate change is global, with people everywhere worsening the crisis. But we are not all equally responsible for the crisis we face now. Those of us who live in the wealthier nations got our wealth by cutting down forests, and burning coal and oil to fuel our industrialization. We are wealthy, to be blunt, because we’re the ones who put most of the greenhouse gases up there in the first place.

In the last century, to get wealthier, you needed smokestacks and clearcuts and coal mines. Poorer nations — whose economies rely more on older, more polluting technologies — argue that they have a right to grow their economies to help their people escape poverty and achieve prosperity. These nations are mostly willing to negotiate with wealthier countries on lowering their climate emissions rapidly, but they will need time to transition to low-carbon economies, and they expect that we in the wealthier countries will lead the way on cutting emissions rapidly to buy them time. Essentially, the poorer nations are saying, they have a right to the lion’s share of those remaining 565 gigatons of CO2.

Even ambitious plans for global emissions reductions take time. Poorer countries now emit less overall, but their economies are inefficient and largely dependent on dirty energy. Lots of work will need to be done for those countries to level off their emissions, and more work after that for their economies to become carbon neutral, even with really aggressive innovation — innovation bolder than any we have seen anywhere in the developing world. For example, one recent credible scenario by Kevin Anderson and Alice Bows would have emissions in poorer countries leveling off in 2025, then declining 7 percent per year thereafter, until the global carbon balance was restored. Seven percent a year, it should be noted, would be extremely bold: but even that extremely bold goal would demand that the wealthier countries buy time by zeroing out their own emissions first. The poorer countries argue this is a matter of “climate equity.”

Since we need their agreement, and their action, it’s probably smart to just go ahead and admit they’re right. It would be unjust to ask the world’s poor countries to absorb the costs of taking actions we ourselves avoid, in order to solve a problem we mostly created. We need to go first in zeroing-out our emissions.

But here’s the thing: far from being some unbearable burden, rapid reductions to net-zero emissions may in fact offer wealthier nations our best opportunity to rebuild our economies to prosper in the 21st century. To understand why, we need to look at the kind of planet we’re becoming: an urban planet.

Our urban future

Humanity is already an urban species, with more people living in cities than in the countryside. By the middle of the century, we will likely have as many as 9.5 billion people living on the planet, with 70-75 percent of us (around 7 billion people), demographers estimate, living in cities themselves, and 95 percent or more of humanity living within a day’s travel of a city. By the 2050s, the overwhelming majority of humanity will be participating in urban systems of health care, education, communication, commerce, and government that only a few decades ago were limited to the “developed” world.

Growth is transforming the very nature of cities. Every day, at least 200,000 people move to cities or are born in them. That’s like building a city the size of San Francisco every four days. Then doing it again, four days later. Then doing it again — and repeating the process several thousand times in the next 40 years. By 2050, we will have an estimated 3.5 billion more urbanites, and to house them we will have built a constellation of thousands of large cities, including a scattering of extremely large megacities, each home to tens of millions of people. The largest city-building boom in human history will happen in the next four decades, with each decade experiencing more change than the one before.

This urban boom won’t be wonderful for everyone; for many, it may be tragic. Unless we change our priorities quickly, as many as a billion people — climate refugees, the rural and destitute, victims of conflict and deep structural poverty — will live on the very edge of existence. Perhaps as many as 3 billion people will live in informal settlements — in the huge slums springing up around many developing world cities. Hundreds of millions of these slum-dwellers will live in abject poverty. Inequalities will strain our societies. In the midst of widespread poverty, 3 or 4 billion others may rise out of poverty to enter the global middle class, living what we today would consider a “modern” — if modest — life. A billion may well live in even greater affluence than we experience today. And the one thing the vast majority of these people will have in common is their cities, and the ways in which those cities are linked together.

How we build this coming wave of cities will largely decide not only the quality of life of the people living in them, but also the future of our planet. Because how we build our cities will decide, more than any other factor, how much we heat the planet.

Our urban opportunity

Climate emissions are a byproduct of the global economy; but the links that connect that economy together are forged in our great cities. In this book, we’ll see how the choices cities make about how they grow will largely determine whether their economies will be clean or dirty; and the choices these cities make, in aggregate, will largely determine whether the global economy as a whole will be catastrophic or full of possibilities.

In 40 years, humanity will live in thousands of these major cities, each stamping the global economy with its own character — and burdening the planet with its consumption and pollution, to greater or lesser degrees. But right now, the economies of only about 200 cities define the global economy. These cities and the regions surrounding them are responsible for the vast majority of their countries’ prosperity, and also of their countries’ greenhouse gases.

Most of these cities are still in the wealthier nations. If our cities reinvent themselves, finding pathways to low-to-no-carbon futures, our nations can rapidly cut climate pollution, even if most of our compatriots lag behind in reducing emissions. Building cities that produce no net emissions — that reduce emissions to the extent that the greenhouse gases generated can be balanced through other actions that draw CO2 out of the atmosphere (what I call “carbon zero” cities) — may in fact be the smartest, quickest pathway to lowering national emissions.

Furthermore, the options that will be available to those thousands of emerging cities over the next 40 years largely depend on the choices we in the world’s wealthiest cities make today. The reason is that innovation and invention move slowly, yet are critical. When no new solution is available, business as usual is a given. Once a better solution to a given problem has been found, its spread can be hastened, though innovation diffusion still takes time. As the wealthier cities design away their own emissions, many excellent new solutions will be created, resulting in zero-emissions pathways poorer cities will be able to follow as they get wealthier.

There’s no time to lose. The costs of action will rise, not fall, with time. Many big investments have long life spans: They can operate for decades — and need to, in order to pay back the costs of their construction. This makes it politically very hard (and sometimes economically expensive) to shut down new infrastructure and industrial systems, even when those systems are producing unwanted results. What we build in the next two decades will probably be with us for decades more. Making new investments in old, dirty ways of doing things (like coal-fired power plants, highways, and suburban sprawl) retards change, and commits us either to continued pollution or to costly retrofits and replacements in the near future. But also, the longer we wait, the more the consequences of climate change already set in motion will hamper our progress and make us less able to act. All of the impacts of climate change have human costs, in many cases quite large. Few have any benefit at all. The longer we wait, the more our economic capacity for change will be damaged by droughts and floods, rising oceans and spreading diseases, climate refugees, and political instability. This is not even to mention the increasingly heart-wrenching human costs or the psychological trauma caused. Sandy was just a taste of what climate change could cost us.

Our cities as climate solutions

So, changing how our cities work proves to be a pretty vital job. Fortunately, our comparatively massive wealth has left us with a number of capacities the rest of the world simply doesn’t have: The majority of the world’s research universities, think tanks, engineering and design firms, advocacy groups, investment funds, venture capitalists, and so on, are all concentrated in the wealthiest cities — and even with China, India, and Brazil growing by leaps and bounds, this central fact of the concentration of the capacity for innovation in a relatively small number of rich cities is unlikely to change overnight.

Leading the way into a carbon zero future will be good for business. Cities that innovate in design, planning, policy, and products will equip their citizens with exportable skills and marketable experience before those in slower cities even know they exist. With thousands of large and small cities about to boom, the markets for urban innovations are almost inconceivably vast. There’s a 40-year boom on its way; cities that lead the way into a carbon zero future will be its great success stories.

Many of the most important kinds of innovations, policies, and plans needed to create such urban success stories are local — or are, at least, the kinds that don’t demand bold national action to succeed. In countries like the United States, where dirty energy companies have managed to clog the works of government, the ability to innovate meaningfully at a local level represents a huge advantage. Our major cities are small enough that committed people can actually change them, and large enough that changing them can produce big impacts.

Americans, Canadians, and Australians, in particular, sail now on a collision course with planetary realities. Our sprawling suburbs and low-density cities depend on abundant resources, cheap oil, and low costs for pollution, none of which the future holds. No amount of political grandstanding will change that fact. Sprawling, auto-dependent suburbs are unsustainable, and that which cannot be sustained does not long continue. For the size of their populations, our cities are the most climate-damaging in the world.

Even Northern European cities, with their older, more compact urban forms, better transit, and reputations for climate leadership, are far from sustainable — they, too, need a lot of change — but I have chosen to focus on North American cities precisely because that is where we need the biggest change in the shortest time. (Readers from the rest of the world should find a few ideas worth mulling over — much of what applies to North America applies without too much translation to Australia and New Zealand, as well as in parts to much of Europe and the prosperous parts of Asia, especially Japan and Korea. Around the world, leadership will take different forms: the imperative to lead will be the same.)

I’m writing most directly to my fellow Americans, though. That’s because I care deeply about my country, as do most Americans. I believe that if we truly love our country, we must care about its future; and we can’t care about its future without taking into account the ways our nation’s actions today are shaping that future; without attempting to steer a course that will leave our countrymen better off in the future. To love our country today is also to wish to see it secure and prosperous tomorrow. So to be patriots, we have to want to be good ancestors to those who are coming after us. And being good ancestors today means, perhaps above all else, fighting climate change. No greater threat faces America in the coming years than climate chaos. We learned that with Katrina; we’ve learned that with droughts and floods and wildfires; and now we’re learning it afresh as our nation recovers from the assault of a superstorm of unprecedented size. And the biggest storms are still ahead.

Building carbon zero cities means not only greater prosperity, but more security. Almost everything we need to do to drop our climate emissions also leaves us more rugged and resilient to disasters and global instability. Carbon zero cities mean future-proof cities, or as close as we’re likely to get.

Our choice could not be clearer, to my mind: Remake our cities into central hubs in the global climate-neutral economy we’re moving towards (and ready ourselves for the tough times to come), or shirk our responsibilities and leave ourselves even more vulnerable to the onrushing chaos. As a patriot, the right choice for America is plain to me.

Imagining carbon zero cities

How do we get to work? Well, we can’t build what we can’t imagine, so the first task in building carbon zero cities is to reimagine the cities we have.

Reimagining is hard work. It requires both a robust conversation about what carbon zero cities might be like, and a far more creative approach to envisioning the kinds of innovations and solutions that could get us there. This little book is my attempt to outline one version of a carbon-neutral city; to get a conversation going about what kind of change a 90 percent cut in emissions might entail; and to point out some of the main areas of possible innovation.

It’s worth emphasizing that this is a sketch, not a blueprint. I wouldn’t even attempt to ordain a model for zero-carbon development that every place should adopt. Every city is unique, with its own character, geography, civic culture, and history. Regional economies and politics have left every metro area with different workforces, institutions, and business cultures. The implementation of national policies and local capacities vary widely. No one set of innovations applied in a specific way will suit the needs of every city. Large teams of professionals and engaged citizens should (and I hope, will) take up the actual work of upgrading their cities. I’m not interested in dictating approaches to anyone.

Indeed, it seems to me that what we need most right now are not conclusive answers, but good hypotheses put immediately to the test; and good hypotheses spring first from reframing our understanding of a given challenge. I hope that my reframing of this challenge will influence readers to begin to see their own cities’ challenges in a new light.

But don’t expect things to look normal, illuminated by the demands of the future. We have, again and again, mistaken what we think of as “normal” for “best” and “permanent.” Normal as we knew it in the second half of the 20th century is already a thing of the past. Already, many of our older systems are crumbling, revealing themselves to be unsustainably expensive or indefensibly harmful. Even the timescales of the 20th century are out of date. Changes that took half a century before are erupting in a few years now.

The speed of change will not slow. It is both pulled along by the dire necessity of quick action — for, as Donella Meadows has written, on a planet full of limits, “Time is in fact the ultimate limit” — and driven along by the unleashing of innovation, collaboration, and competition on a planetary scale that dwarfs anything our great-grandparents could have comprehended. If the ultimate limit turns out to be time, the last infinite resource turns out to be creativity.

I believe that planetary limits and human creativity are now inextricably bound together. I doubt we’ll reinvent the physical limits of this world, at least in the next few centuries. I would bet against the emergence of any technologies that allow us to exceed our planetary boundaries on both a global scale and a sustained basis. But I would also bet we can build a civilization that works within our planetary limits, and furthermore, that the realm of possibilities for human experience within those ecological limits is essentially infinite.

Indeed, as we cease trying to maximize the volume of material growth and start emphasizing sustainable prosperity, I think we’ll find that what we’re able to do with energy and materials becomes more and more brilliant, meaningful, and enriching. Design constraints often deliver better results than a belief in complete freedom. Quite the opposite of imposing hardship, carbon zero targets may very well spur a renaissance in urban creativity.

The straining limits that pressure us to remake our cities will likely produce an unprecedented blooming of applied creativity and civic acumen. I find it completely likely that the constraints of climate neutrality and ecological sustainability, boldly met, may produce the most livable, prosperous, and resilient cities the world has ever seen.

Nothing in this book is utopian: Most of what I suggest is already being implemented or experimented with somewhere, though no city I know of has put all the pieces together in one place. Some of what I suggest still lives in the realm of conjecture, but that realm is not as far away as it used to be.

I hope you will take my sketch, use what makes sense to you, discard what doesn’t, and begin your own drawings of what the future’s possibilities can be — they are bound to be better than mine, and the world needs every well-grounded, well-crafted vision it can get. Please, don’t just read: reimagine.

Read the sidebar to this chapter: Consumption-based footprinting.

Read on: Why clean energy isn’t enough