Earth in Human Hands

Shaping Our Planet's Future


By David Grinspoon

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NASA Astrobiologist and renowned scientist Dr. David Grinspoon brings readers an optimistic message about humanity’s future in the face of climate change.

For the first time in Earth’s history, our planet is experiencing a confluence of rapidly accelerating changes prompted by one species: humans. Climate change is only the most visible of the modifications we’ve made–up until this point, inadvertently–to the planet. And our current behavior threatens not only our own future but that of countless other creatures. By comparing Earth’s story to those of other planets, astrobiologist David Grinspoon shows what a strange and novel development it is for a species to evolve to build machines, and ultimately, global societies with world-shaping influence.

Without minimizing the challenges of the next century, Grinspoon suggests that our present moment is not only one of peril, but also great potential, especially when viewed from a 10,000-year perspective. Our species has surmounted the threat of extinction before, thanks to our innate ingenuity and ability to adapt, and there’s every reason to believe we can do so again.

Our challenge now is to awaken to our role as a force of planetary change, and to grow into this task. We must become graceful planetary engineers, conscious shapers of our environment and caretakers of Earth’s biosphere. This is a perspective that begs us to ask not just what future do we want to avoid, but what do we seek to build? What kind of world do we want? Are humans the worst thing or the best thing to ever happen to our planet? Today we stand at a pivotal juncture, and the answer will depend on the choices we make.



A Planetary Perspective on the Human Predicament

Gazing over the countless fluctuations and transformations in Earth's multibillion-year history, I am struck by the unique strangeness of the present moment. We suddenly find ourselves sort of running a planet—a role we never anticipated or sought—without knowing how it should be done. We're at the controls, but we're not in control. This book is my view of how we got into this situation, and where that leaves us now.

A child of the space age, I grew up captivated by the romance of planetary exploration. My timing was right to become a NASA research scientist working in the new field of astrobiology, the scientific study of life in the universe. My participation in the spacecraft exploration of other planets has informed my view of our presence on this one. In these pages I'll describe how we humans fit into the long-term story of Earth, and how I believe this knowledge can help us to navigate our current time of environmental stress and uncertainty about the future.

Although climate change is the most obvious, it is only one of a large number of interconnected ways in which we have suddenly begun to modify the planet we inhabit. The scientific community is now converging on the idea that we have entered a new phase, or epoch, of Earth history—one in which the net activity of humans has become a powerful agent of geological change, equal to the other great forces of nature that build mountains and shape continents and species. The proposed name for this new epoch is the "Anthropocene" or the age of humanity. This concept challenges us to look at ourselves in the mirror of deep time, measured not just in decades or centuries or even in millennia, but over hundreds of millions and billions of years.

The realization that humans may have initiated a new geological phase also disrupts and rearranges all our systems of timekeeping. Think of these three timescales: human history with its long procession of civilizations, migrations of people, and waves of technologies, ideas, and modes of thought; geologic time with its ages and epochs marking fluctuations in environment, climate, and sea level, recorded in the layers of rocks; and, closely related, biological time, the evolving stages and forms of life logged in the fossil and molecular records. The Anthropocene represents a braiding together of these into one inseparable narrative. This is "the end of history," and of biology and geology—at least as separate stories. Have they become irreversibly entwined? It's conceivable that there may never again be geological change without human influence.

We are witnessing, and manifesting, something unprecedented and still completely unpredictable: the advent of self-aware geological change. As an astrobiologist, I study the possible evolutionary relationships between life and the planets that may host it. I see the Anthropocene as a tricky new step in the long, intricate dance between Earth and its biosphere that has been going on for four billion years. There are those who object to the name Anthropocene as being too self-aggrandizing and serving a destructive, human-centered viewpoint. But this epoch is well-named because it represents a recognizable turning point in geological history brought about by one species: anthropos. And our growing acknowledgment of this inflection can be a turning point in our ability to respond to the changes we've set in motion. I believe that, more than the extreme and undeniable physical changes to the planet being caused by human influence, it is this dawning self-recognition that is really fundamentally different and, ultimately, promising about the Anthropocene. Many species have changed the planet, to the benefit or detriment of others, but there has never before been a geological force aware of its own influence.

Popular treatments of this rich subject have too often focused on the ongoing argument about whether or not the Anthropocene should officially be recognized as a new epoch within the geologic timescale, and at what point it began. Yet that debate has spurred a fascinating re-examination of the various stages of encroaching and accelerating human influence on Earth since the end of the last ice age twelve thousand years ago. And the Anthropocene has now garnered the attention of people thinking far afield of geologic timekeeping. The sharp human torqueing of Earth's landscapes, habitats, and global cycles presents a range of challenges that go well beyond the physical and biological sciences.

In 2012, I saw an announcement that opened up a door for me. The John W. Kluge Center at the Library of Congress, in partnership with the NASA Astrobiology Institute, was advertising a new position, a chair of astrobiology. They would support a scholar in residence to pursue "research at the intersection of the science of astrobiology and its humanistic and societal implications." I fantasized that this might give me the opportunity to write the book that you are now reading. My proposal was accepted and I was selected as the inaugural chair. I was psyched just to have some time to read and write, but I soon discovered how truly fortunate I was. The Kluge Center is a scholar's dream: a supportive place to study, converse, and create, set within the ornate, infinitely stimulating palace of learning that is the Thomas Jefferson Building. I initially wondered if, as the only physical scientist there, I would be off playing in my own corner of the sandbox. I quickly learned that many of the humanists—historians, literary theorists, and theologians among them—were also keenly interested in exploring the changing relationship between humanity and the planet. My conversations with them1 were great fun, and I hope that some of the broadened perspective they provided has found its way onto these pages. Also among the joys of writing in Washington is the group of local scholars I've come to know, who are studying the Anthropocene from many different points of view. Our informal "Washington Anthropocene Group" started meeting at the Library of Congress, and has since migrated to several museums and universities, often continuing the conversation at local bars. I'm the only astrobiologist, but we've had geologists, historians, geographers, anthropologists, paleontologists, materials scientists, and others. At conferences and on the Web, I've met philosophers, ethicists, artists, and economists, all wrestling with the concept of humanity as a planet-changing force. Whatever its fate as an official geological time period, the concept of the Anthropocene has sparked a thousand worthwhile interdisciplinary conversations about the human role on Earth.

I don't believe in "great person" theories of science history. Ours is a team sport, a transpersonal endeavor. No individual is essential, and all worthwhile ideas will emerge eventually. But the story is also full of brilliant heroes and colorful characters who carve out the specific, somewhat random path science takes toward understanding. Without bombarding you with names, I do want to share some tales of a few of the people I've worked with or been influenced by. In looking over my manuscript, I notice that a disproportionate number of these people are men. Among other things, this reflects a tremendous loss to science, of potential contributions by those who have not been as welcome in our field. Of the five scientists I think of as my closest mentors, all are men. This is not unusual for a scientist who started out in my field in the 1980s. We are making progress, and it would be much more unusual for a scientist starting out today. Though the history of science is dominated by men, the future of science is not.

One of the characters who winds his way through this book is astronomer Carl Sagan. My own personal connection with Sagan began when he and my father, a professor of psychiatry, bonded over the fact that, at one point, they were among the few Harvard faculty opposed to U.S. involvement in the Vietnam War. They became best friends and from the age of six I grew up around "Uncle Carl." When I was a kid, his tales of space exploration and speculations on human evolution cast a powerful spell. In college I worked summers in his laboratory at Cornell, zapping mixtures of gas to simulate the organic goop on Saturn's moon Titan and mathematically modeling potential alien signals. Later still, we worked together on a study of Earth's early climate that became part of my doctoral dissertation.

Carl also introduced me to Jim Pollack, who had been his first grad student at Harvard, and who decades later became my postdoctoral adviser at NASA's Ames Research Center, where many of the scientific breakthroughs I describe in this book took place. In the 1970s, '80s, and '90s, Sagan, Pollack, and other planetary scientists modeled runaway greenhouses, asteroid strikes, and nuclear winters, along with the possible "terraforming" of Mars, Venus, and other worlds. Long before the current debate on whether or not we should consider "geoengineering" our planet, purposefully tweaking it to compensate for our clumsy climate modification, Sagan and Pollack were considering how humans might transform planets both accidentally and deliberately. The research these scientists did on planetary climate catastrophes informs my view of Earth's history and the new kind of human-induced catastrophe it is now experiencing.

It may seem circuitous to begin a book about the human role on Earth by talking about the exploration of other planets. I will try to make the case, however, that looking homeward from the vantages we've gained through our interplanetary journeys gives us valuable perspective for navigating the planetary-scale changes we are now facing—and causing. We need to learn all that we can about how planets work, so we can make the transition from inadvertently messing with Earth to thoughtfully, artfully, and constructively engaging with its great systems.

The planetary perspective allows us to step away from the noise of the immediate present, to see ourselves from a distance, in time-lapse. When we do so, what we see is not just a problem facing our civilization but an entirely new evolutionary stage in the development of life. In seeing ourselves as a geological process, we also see the planet entering a phase where cognitive processes are becoming a major agent of global change. Earth's biosphere gave birth to these thought processes, which are now in turn feeding back and reshaping its changing planetary cycles. A planet with brains? Fancy that. Not only brains, but limbs with which to manipulate and build tools. We are just beginning to come to grips with this strange new development. Like an infant staring at its hands, we are becoming aware of our powers but have not yet gained control over them.

It's a challenging moment for human civilization. The great restless cleverness of our species has gotten us into a tough spot. Our collective actions, over which we often seemingly have little control, threaten the well-being of many of our fellow humans, not to mention vast numbers of our more distant biological relatives. Our very survival may be threatened. Paradoxically this comes at a time, and even largely as a result, of unparalleled advancement in our scientific and technological prowess. But if we're so great at figuring things out and inventing solutions to survival problems, how come we're in this mess? Part of the reason we are, so far, stumbling through this transition is that we have not yet seen it clearly for what it is. I think our fundamental Anthropocene dilemma is that we have achieved global impact but have no mechanisms for global self-control. So, to the (debatable) extent that we are like some kind of global organism, we are still a pretty clumsy one, crashing around with little situational awareness, operating on a scale larger than our perceptions or motor skills. However, we can also see our civilization, such as it is, becoming knitted together by trade, by satellite, by travel, and instantaneous communications, into some kind of new global whole—one that is as yet conflicted and incoherent, but which is arguably just beginning to perceive and act in its own self-interest.

We have, unconsciously, been making a new planet. Our challenge now is to awaken to this role and grow into it, becoming conscious shapers of our world. We have to "human up" and accept the responsibility we've stumbled into. We didn't ask for this. And we may not be up for the challenge, but at this point we have no choice. However we got here, we find ourselves dominating many of our world's systems and needing to learn, under duress, how to handle that. It's a complex task, and we have to learn how to do it without a manual and on the fly. Fortunately, we may have a leg up. There are some ways in which our evolutionary history and our unique plasticity as a species may equip us for the job.

Some of the most amazing things are very easy to take for granted. How cool is it that I am writing this and you are reading it? By thwacking away at these dirty little plastic keys in some coded pattern, I'm sending you a detailed message over malleable expanses of space and time. What is this magic? Our fingers were not evolved for this. They were made for grasping and throwing, touching and feeling, making tools, making dinner, making love. And yet here we are. These human hands and the nervous systems they are wired to are so flexible, seemingly made to be rewired as needed. Time and time again our species has escaped existential threats by reinventing ourselves, outsmarting the toolkit evolution gave us, finding new skills not coded in our genes to survive new challenges not previously encountered by our forbearers. We've bounced back a few times from the edge of extinction, and ultimately thrived due to our abilities to communicate, work collectively, adapt creatively to changing environments, and solve problems through technological and social innovation.

Now we need to do so again. To do the Anthropocene right, we'll have to use our innate skills at cooperative problem-solving and innovative tool use to become more effective global actors. We would so like to avoid this reality, this responsibility, but having seen what we've seen, and what we've done, we can't go back to being ordinary members of the animal kingdom. We also can't afford to ignore natural constraints, or imagine we are so clever we can just invent our way right past them.

I think we're junior apprentice planetary engineers. We can't shrink from this role and to do it well will require finding a much deeper understanding of both our world and ourselves. We have, without knowing it, thoroughly reworked our planet. Now that we are realizing this, what should we do? We cannot un-rework it. So we need to rework ourselves into the kind of creatures who can successfully play the role we've unwittingly assumed.

It sometimes seems to rub people the wrong way to say anything sympathetic about humanity, positive about our potential influence on Earth or hopeful about our future. How could you not be shocked and alarmed by our jarring, accelerating influence on this planet? We rightfully feel some deep regret, and some shame, at how we have (not) managed ourselves.

However, our obligation now is to move beyond just lamenting the job we've done as reluctant, incompetent planet-shapers. We have to face the fact that we've become a planetary force, and figure out how to be a better one. By seeing our role clearly, we take the first step toward assuming our responsibilities. We need to pause and look up at the distant horizon to see where we really are. A planetary view of the human journey, where we take in the wider timescape, suggests that we are not stuck, just disoriented, not evil, just confused, struggling to find our way in a world increasingly of our own making, and confronting aspects of our existence for which we are not yet fully equipped. We've been building an expanding, rapidly changing civilization on a finite world with no long-term plan. Our challenge is to acknowledge, with clear eyes, the tough predicament we're in, and not to succumb to toxic fatalism. Our most valuable resources—creativity, communication, invention, and reinvention—are in fact unlimited.

Our oblivious stumbling into ecological and climate danger could be just a phase, characterized by inadvertent, clumsy human interaction with planetary systems. There is another way to do this. I'll describe some examples of a more thoughtful mode of engagement that, while still in its infancy, is clearly something we are capable of. I believe the true Anthropocene, what I call the "mature Anthropocene," characterized by intentional, deliberate interactions with the planet, is something that should be welcomed. Though it is only in its infancy, it can already be glimpsed. Awareness of ourselves as agents of geological change, once propagated and integrated, could provide us with the capacity to avoid doom and to take our future into our own hands.

Here I've been speaking of the human species as one thing, and human civilization as one thing, when obviously both are a great many things with diverse and complex histories. Yet since the problems we face are global, and to some degree our solutions must be as well, this begs the question of who we are really talking about when in this context we say "we." This is a dilemma I will revisit.

The planetary perspective provides a kind of out of body experience for us—hovering in orbit and watching ourselves sleepwalk through a slow disaster of our own making. Now, can this experience help us to shake ourselves awake? For virtually all of its history Earth has evolved without us, and we have always seen ourselves as autonomous actors on a passive planetary backdrop. But now we are beginning to see that our futures—those of humanity and of planet Earth—are tightly conjoined. If human civilization is to persist and thrive we will need a completely different view of our planet, and of ourselves, in which we acknowledge both our deep dependence and our increasing influence. We need visions of a future in which we have applied our infinite creativity to the task of living on a finite world, where we have embraced our role, become comfortable and proficient as planet-shapers, and learned to use our technological skills to enhance the survival prospects not just of humanity but of all life on Earth. My name for this vision is Terra Sapiens, or "Wise Earth."

A recent scientific breakthrough enriches this story: the exoplanet revolution. As we long suspected and have now confirmed, this universe is full of planets, orbiting nearly every star. It is now very close to inconceivable that we could be the only life, and only technological intelligence, in the universe. An interplanetary perspective on Earth's current dilemmas incites us to wonder whether parallel dramas may have unfolded on distant worlds. Do other planets also grow inventive brains that end up causing themselves problems? Do other species develop technology and build civilizations that create dangerous instabilities on their planets? How do they cope? Do planetary biospheres become self-aware? The Anthropocene leads us to a new way of looking at SETI—the search for extraterrestrial intelligence—which in turn illuminates changing notions about ourselves, how we fit into our planet, and what kind of future we dare imagine.

One hundred million years from now, what will our time have been? A brief climate spasm that Earth shrugged off and largely forgot, leaving a thin layer infused with bizarre plastic objects? Or the beginning of a lasting new phase when the biosphere finally woke up and adjusted its grip on the planet?

In 1758, when Carl Linnaeus—the Swedish botanist who invented modern biological taxonomy and classification—needed a name for the human species, one that distinguished us from others in the genus Homo, he called us Homo sapiens, or "wise apes." Is this a good name for us? Or was this wishful thinking? Linnaeus saw that we were good at problem-solving, and he was himself an exemplar of the scientific revolution in which the human intellect was rapidly teasing apart the mysteries of the universe like no other animal could. We had learned to "tame nature" in so many ways. We had reason to be proud of ourselves. But at that time Linnaeus could scarcely have conceived the kind of wisdom that we need now. We've been so successful at solving problems of survival in many different local environments that we've exponentially increased our numbers and global influence. We've spread ourselves so widely around the planet that we're now confronting a new environmental factor that may not be so easy for us to tame: ourselves.

What does wisdom mean for a species with the power to change its home planet, affecting the fortunes and futures not only of themselves but of all life? Certainly it requires us to comprehend our role in the physical workings of the planet and to act in ways that are not obviously self-destructive. It is strange that geology and planetary science, investigations we began out of simple curiosity, have now become crucial forms of self-knowledge. Although science has helped us stumble into the Anthropocene trap, it also provides the tools with which, armed with wisdom, we could spring ourselves from it.

Can we live up to our name and create a wisely managed Earth? We have no choice but to try, because events we have already, unwittingly, set in motion are leading us inevitably toward a branching point between calamity and wisdom. Yet once we overcome the fear and embrace this new reality, then thrilling new future possibilities for our planet and ourselves open up before us.



And you may ask yourself, well, how did I get here?

—Talking Heads, "Once in a Lifetime"

Sidewalk Wisdom

For the past two years I've been living in a carriage house on Capitol Hill, seven minutes' walk from my office in the Library of Congress. It's a leafy, gentrified neighborhood of colorfully painted restored Victorian brick houses, and on sunny weekend days you can score all manner of quality household items on the wide cobbled sidewalks, choice stuff left free for the taking by residents too generous or busy to dispose of them otherwise. The boxes of books that appear weekly along East Capitol Street (a stack of used baby manuals, a pile of tomes on population dynamics from a year at an NGO, discarded cookbooks from someone's vegan phase) provide irresistible glimpses of the lives in these handsome Washington homes, and occasional serendipitous enlightenment.

Once, on Seventh Street, I spotted a sky-blue book lying on the redbrick curb. Upon approach, I saw it was Anatomy of the Sacred: An Introduction to Religion (sixth edition), by James C. Livingston, conspicuously folded open to a specific page. A message of some sort? I brushed off the dirt and read:

Whatever the cause of our unease and strife, few thoughtful persons would deny that we humans have, over the millennia, sensed a tragic flaw, a falling short of our potential, a missing the mark of life as it was meant to be or should be. Something, we feel, is "out of joint."

"How true," I thought. "What is it about humanity?"

The very next day, I found a true treasure, containing one possible answer. In a carton of mostly forgettable, fluffy self-help books, out-of-date travel guides, and other discards, an old textbook caught my eye: Psychology Today: An Introduction (second edition, 1972). Reflexively I glanced at the list of contributors on the inside cover. At the very bottom, it read, "Chapter Introductions by Isaac Asimov." Say what? Are you kidding me? I took that one home. Each of the thirty-four chapters is preceded by a short, informal essay by the great science-fiction maestro. The writing is playful, irreverent, personal, and insightful. Asimov introduces each topic of human psychology by riffing on free will, the nature of consciousness, intelligence, and morality, and his famous "laws of robotics." These constituted Asimov's science-fictional device for ensuring that conscious robots could not behave dangerously. If we invent powerful, capable machines with smarts, awareness, and autonomy, we might, he imagined, build into the very fabric of their minds inviolable ethical precepts to be obedient, cooperative, and altruistic. Asimov was prescient. Today his laws come up frequently in discussions about how we can keep artificial intelligence from becoming threatening. Yet his robots were also foils for us and our troubled relationship with our own runaway cleverness. His stories explored the conflicts inherent in complex moral minds, whether evolved or engineered with technologically amplified capacities.

In one of these microessays, Asimov summarizes the way in which life has organized itself into a hierarchy of structures, with organisms at each level being built from collectives of simpler organisms. He looks at where we ourselves fit into this scale-spectrum of complexity. First there are the viruses, which are almost too simple to be alive. They seem more like molecules than creatures, each not much more than an encapsulated coil of RNA or DNA. The ultimate freeloaders, they hijack the machinery of more fully developed living cells in order to function. Then there are the simplest, undifferentiated cells, the bacteria. More complex cells are made up of various component parts, each of which is itself rather like one of those simple bacterial cells. These complex cells can exist as free-floating individuals or can be loosely bound with others in various colonial arrangements. Finally, as Asimov describes,

cells can drown their individuality and abandon their free-living abilities in order to form a multicellular organism, which may be as simple as a flatworm, or as complicated as a giant sequoia, a whale or a man.

He points out, however, that the hierarchy does not end there. A multicellular organism by itself is often useless. It needs others to survive and propagate. All but the simplest reproduce sexually. Many are dependent for their survival on more complex social arrangements: a herd, a school, a flock, or, in our case, a tribe or society. Some (for example, the social insects) have such tight interdependence with other individuals that they form what might be called superorganisms, and in those cases, it may legitimately be questioned whether individuality resides in the organism or the hive.

Just as we individual humans are multicellular organisms, each an exquisite arrangement of forty trillion cells, with the whole being greater than the sum of its parts, so we cannot fully manifest our humanity, or survive for long, without joining together to form larger associations. Asimov sums it up:

As individual multicellular organisms, however, we would be less willing to agree that a complex society or state is greater than the sum of the individual organisms making it up. We would be less ready to judge that it is a cheap price to give up our individualism to become part of a society.

Yet the tug is there. It is as though we are at some stage of evolution between the multicellular and the multiorganismic.


On Sale
Dec 6, 2016
Page Count
544 pages

David Grinspoon

About the Author

David Grinspoon is an astrobiologist, award-winning science communicator, and prize-winning author. In 2013 he was appointed the inaugural Chair of Astrobiology at the Library of Congress. He is a frequent advisor to NASA on space exploration strategy, and is on the team for the Curiosity Mars Rover. Grinspoon’s writing has appeared in the New York Times, Slate, Scientific American, Seed, Boston Globe, and the Los Angeles Times.

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