The barracks built inside one of the ice tunnels at Camp Century.
Imagine you are a time traveler who just landed on Earth 2.7 billion years ago. As you step outside on this younger version of our planet, what’s your first experience? The answer is pretty simple.
You die.
To be specific, you asphyxiate. For about the first two billion years of Earth’s history, its atmosphere contained only minute traces of oxygen, even though it had long been a home to life. For almost half the planet’s history, its “air” was composed almost entirely of nitrogen and CO2.1 Today, however, the Earth’s atmosphere is almost all nitrogen and oxygen, with only a tiny fraction of CO2. What happened to make so great a change?
This one all-important detail about Earth’s history—the rise of its oxygen—is a lesson for us today. It was life, acting on a global scale billions of years ago, that altered the planet’s atmosphere. In doing so, it also changed the future history of the Earth, leading to humans and our project of civilization. Now life, in the form of our civilization, is once again poised to alter the planet’s atmosphere and its complex machinery of evolution. The comparison of that time, billions of years past, with our own moment of climate change offers a doorway into the remarkable story of the “masks of Earth.” Its narrative bears a truth few of us recognize.
Our world has been many planets in the past.
These other versions of Earth were profoundly different from the cloud-mottled, blue-green world we know today. Each was a consequence of planetary forces shaping and then reshaping our world. Together, they reveal how deeply humans and our project are part of a much longer story. When it comes to life changing the planet, we are neither unique nor unusual. That’s why the story of our planet’s past, a story that is fundamentally astrobiological, is so critical to us. Knowing the Earths that were will give us the vocabulary to craft a new story, one that keeps us part of the Earth soon to be.
NO EASY DAY
The Polecat arctic transports were beasts. Designed for duty in the harshest conditions, each was the size of a minibus. The caterpillar-treaded special-purpose vehicles were built wide to keep them steady on uneven terrain, with powerful diesel engines for hauling cargo and personnel across ice, snow, or even up the steep side of a glacier.2
On October 16, 1960, the side of a glacier was all young Soren Gregersen saw as he looked out the window of his assigned Polecat. Just a few hours earlier, Gregersen, a seventeen-year-old Danish Boy Scout, had been stuffed into the Polecat’s cab by a smiling GI. Two days before that, he’d landed at the US Air Force’s Thule Air Base on the western shore of Greenland and been outfitted with regulation cold-weather military gear. Gregersen watched in wonder as the Polecat began its long trek up the “ramp,” a sloping road carved into the glacial ice. He was beginning a 150-mile trek out onto one of Earth’s most inhospitable locales.3
Bouncing around the Polecat’s cab, Gregersen was caught somewhere between excitement and terror. After all his hopes, preparations, and travel, it was really happening. He was on his way to Camp Century, a city the Americans built under the ice.
At the same time that Jack James was blasting Mariner probes to the planets and Frank Drake was tuning his radio telescope in search of alien civilizations, the US military was pushing audaciously across a different kind of boundary. This one, where Boy Scout Soren Gregersen was bound, lay at the top of the world.
Greenland is a giant ice slab where seven hundred thousand square miles of glacier rise a mile and a half above sea level.4 Temperatures at the center of its vast ice plateau typically drop to a Marslike –70 degrees Fahrenheit. Winds routinely sweep across its barren plains of snow at 125 miles per hour.5 And yet, in 1959, the US government chose to build a military base and a scientific laboratory right in the middle of Greenland’s frozen emptiness.
The logic of the Cold War led the US to plan the impossible in the form of Camp Century. The base consisted of twenty-one trenches dug into the ice, each up to three football fields long. Each trench was twenty-six feet wide and twenty-six feet deep, with snow packed across steel arches to create a ceiling. Prefab buildings, hauled across the glaciers, had been laid into each trench to serve as barracks for the camp’s two hundred servicemen and scientists. Powering the base required a $5 million portable nuclear reactor that the military dragged out across the ice sheet.6 Taken together, building Camp Century required a monumental effort, but one that would achieve a monumental breakthrough.
In our era, when people who know nothing of climate science make sweeping claims of sweeping ignorance, it’s important to remember the risks required to make that science happen. The soldiers and scientists at Camp Century lived at the edge of the world, and their work carried considerable dangers. Transport flights and crews had to contend with extremes of weather unlike almost anywhere else on the planet. In the summer of 1961, a helicopter crash outside the base took the lives of all six aboard.7 But those GIs, their officers, the scientists, and even Boy Scout Soren Gregersen had all come to Greenland’s glacial wasteland on a mission. “It was the most exciting thing that ever happened to me,” recalled Gregersen, now a retired professor of geophysics, when I spoke with him. “That experience is what got me started in science.”
Camp Century was a joint US–Danish effort (Greenland is a Danish territory). To create publicity for the polar mission, the Boy Scouts in both countries held competitions seeking “junior scientific aides.” In late 1959, Gregersen and American Boy Scout Kent Goering each won their chance to spend five months on, and in, the ice.
“We lived right alongside the GIs,” says Gregersen. “Every day, we got some task required to maintain the base. Sometimes it was chopping away the ice that constantly grew inside the tunnels. Sometimes it was working on the pumps that fed an enormous freshwater reservoir deep in the ice. I loved it all, and all of it was thrilling.”
But for young Gregersen, it was the science that made the strongest impression. There were many reasons why the US military built Camp Century. Plans had been discussed to house nuclear missiles in the ice (the ever-shifting glaciers killed that idea).8 There was also the need to keep watch on the Soviets. Gregersen remembers the vast radar arrays, pointing north, at Thule Air Base. But the military was especially interested in climate. The history of warfare was, after all, full of military campaigns done in by weather. Just as the funding for the exploration of space was opened by the Cold War, the Earth’s climate and its history had also become a military concern. That translated into funding for climate science. The money took scientists to the most remote corners of the planet. It was also how young Soren Gregersen first saw the drills at Camp Century.
In rooms carved from centuries of fallen snow, Camp Century scientists set up drilling derricks, like the kind you’d see in oil country. Their goal was to dive downward through almost a mile of ice and thousands of years of planetary history.9 “I saw the effort being made in those ice drilling labs,” says Gregersen. “And it made a huge impression on me. What they were trying to do—it just seemed amazing—recovering the history of the planet using ancient snow.”
Transformative visions of the world usually come when we find new ways to see it. In science, the ability to get to new kinds of data—literally new ways of seeing—allows us to revise and refresh our understanding. Jack James’s Mariner mission to Venus, Carl Sagan’s Martian dust data, and the radio telescopes at Frank Drake’s Green Bank observatory all rewrote our understanding of astronomy and planetary science. In the decades after World War II, our understanding of the Earth was also being reimagined by new data that had been beyond the reach of earlier generations of researchers. Camp Century was one critical chapter in the story of that change.
Ice ages were still a mystery in 1960. The most certain thing scientists could say about them was that they’d happened. Over the last few million years, mile-thick slabs of ice covered much of the Northern Hemisphere. At least four different times, they ground their way south and then retreated back.10 Each glacial epoch left the planet cold and dry. Ocean levels dropped almost four hundred feet—the height of a forty-story building—as so much of the Earth’s water became locked in ice. In between the ice ages, the planet got reprieves in the form of warmer, wetter interglacial states.11
The Earth endured the last ice age for almost a hundred thousand years. Only after the final laggard glaciers retreated did the project of human civilization begin. Our history of farming and cities, writing and machine building fits entirely within the Holocene: the current ten-thousand-year-old interglacial period.12 And even though scientists knew the basic sequence of events leading to the Holocene, the details of how the climate slipped from one state to another eluded them. They simply didn’t have the data to see the details of the change. What they needed was a way to follow the planet’s temperature, year by year, all the way back to when glaciers were last king. Under the auspices of the US Army’s Cold Regions Research and Engineering Laboratory, Camp Century’s drilling operation gave scientists that record.
The work was led by the Danish scientist Willi Dansgaard and the American geophysicist Chester Langway. The mile-thick slab of ice covering Greenland is maintained by yearly layers of snowfall, packed one on top of the other. The strata of ice, built up year by year over the millennia, form a kind of frozen layer cake. Each layer comprises a record of that year’s climate. Within each layer of ice was a chemical marker that served as a proxy thermometer. Using it, scientists built a high-resolution recording of Greenland’s temperatures going back thousands of years.13
After six relentless years of work, Dansgaard, Langway, and their Camp Century team drilled all the way down to bedrock, more than four thousand feet below the top of the ice sheet. Once the “ice core” data retrieved by the drilling was converted into temperatures, Dansgaard and his colleagues could see Earth’s passage out of the last ice age. Moving backward, they first saw a period of roughly constant temperature stretching back eight thousand years. This was the Holocene, the time during which human civilization had been born and grown to thrive. Going farther backward, they could also see the transition from the warmth of our current climate to the frozen glacial age more than ten thousand years ago (the Pleistocene).14
Along with the smooth transition from the last ice age to the current warm interglacial period, the Camp Century data also showed a series of spectacular short-term shifts that would come to haunt our climate future. Around twelve thousand years ago, in a period called the Younger Dryas, the planet appeared to drop from a warming state back into the icebox. It was a stunning discovery. In just a matter of decades, average temperatures around the planet had dropped by five degrees Fahrenheit in some places and as much as twenty-seven degrees in others.15 If comparably dramatic global changes occurred in the modern era, it’s hard to imagine our project of civilization making it through intact.
Later drilling work in Greenland and Antarctica confirmed the Camp Century studies. One American researcher working in Antarctica recalls a moment of truth when just looking at an ice core made the speed of climate change apparent. The ice changing from light to dark across just a few inches in the core was a visceral confirmation of abrupt large-scale swings in global climate.
The history of Greenland temperatures based on ice core records.
The recognition of rapid climate change presented researchers with a warning the importance of which they could not yet understand. At the time, human-driven, or “anthropogenic,” climate change was nothing more than a possibility discussed in the most abstract terms at meetings of scientific experts. Almost no one was ready to conclude that the kind of rapid climate shift seen twelve thousand years ago might be something we could drive through our own actions.
WHICH EARTH?
Whatever quiet preparations were going on in homes across the Earth, William Anders was not part of them. That’s because Anders was on a spaceship. On Christmas Eve 1968, two hundred thousand miles from the planet of his birth, Anders and fellow Apollo 8 astronauts Frank Borman and James Lowell were becoming the first humans to orbit the Moon.
“Oh my God,” Anders said to his crewmates as he marveled at the view outside the small window of his Apollo command module. “Here’s the Earth coming up,” he said, looking out across the moon’s horizon. “Wow, is that pretty.”
Anders asked for a roll of color film while Borman joked, “Hey don’t take that [picture], it’s not scheduled.” Loading up the camera, Anders stopped for a moment to consider the magnitude of the vision before him. Then he snapped an image of the world that would change the world.16
Called Earthrise, Anders’s picture of the blue Earth hanging above the gray moonscape became iconic. Life magazine named it one of the one hundred most influential images in human history.17 Since then, space-based pictures of azure oceans, swirling white clouds, and green-brown continents have become familiar. But that familiarity is undercut by a striking truth that has been emerging since the time of Camp Century: the planet we know today is not the Earth that was. If you had visited our world one hundred million, five hundred million, or three billion years ago, you would have found a planet that looked very different from Anders’s image.
Exhaustive work going back to the 1800s has allowed geologists and paleontologists to construct a timeline of our world’s history. But only in the last half century or so has that timeline been resolved into the details of planetary change. There are four long eons in the Earth’s history, representing the most important transitions in the planet’s climate and life. These eons are subdivided into eras, which are further divided into periods and epochs. The Pleistocene and Holocene, whose transitions were revealed by Camp Century ice cores, are examples of epochs.18
The planet’s story begins with an unnamed cloud of interstellar gas and dust. Almost five billion years ago, that slowly spinning cloud, close to a light-year across, collapsed under its own weight. The Sun formed at the center of the infalling mass, and a rapidly spinning disk surrounding the young star emerged as well. Within this dense disk, particles of dust began colliding frequently enough to form free-floating pebbles. Those pebbles then collided to form rock-sized objects. The rocks then collided to form boulders, and so on, all the way up to asteroid-sized planetesimals. After between ten million and a hundred million years, gravity drew the planetesimals together and assembled the Earth and other rocky planets (Mercury, Venus, and Mars).19
This was the beginning of the Hadean, Earth’s first eon. Lasting from 4.6 billion to 4 billion years ago, its name speaks to the planet’s hellish conditions. Earth during the early Hadean was covered in a globe-spanning sea of molten rock. Eventually, this magma ocean cooled and hardened, forming a solid surface. But asteroids and comets continued to rain down on the planet, ending in a period called the Late Heavy Bombardment, when our solar system cleared itself of planetary construction debris. Each of these apocalyptic impacts shattered the surface, turning some or all of it back into molten rock. Gases released from the bombardment and the magma oceans it regenerated left the Hadean Earth with an atmosphere composed mostly of nitrogen and carbon dioxide.20
Thus, the Earth was once a fire world of molten seas.
The planet’s first forms of life may have emerged by the end of the Hadean. The repeated asteroid bombardments would, however, have sterilized the world, forcing biology to potentially start over and over again.21 Either way, by the beginning of the next eon—the Archean—the kind of life we know today was already in place. The Archean lasted from 4 billion to 2.5 billion years ago. It was during this vast span of time that life based on the biochemistry of self-replicating molecules called DNA spread across the world. But in the Archean, all life consisted of simple, single-celled organisms living in the oceans. The reason for this watery fixation was simple: the whole planet was pretty much an ocean.22
While continents now cover about 30 percent of the Earth’s surface, during the Archean they had yet to “grow.” The ground you stand on today is composed of granite that is less dense than the black volcanic basalt making up the ocean floor. Granite is formed deep within the Earth’s mid-layers (called the mantle). Like warm air in a cold room, granite rises slowly upward as it forms, allowing it to become separate from the more dense ocean crust. While there remains controversy about the process, many scientists believe that during the Archean the continent making was still beginning. Rather than planet-spanning continents, the world hosted just one or two proto-continents called cratons. Each craton was smaller than India is today.
Thus, the Earth was once a water world of almost endless ocean.
Life slowly explored new domains of structure and metabolism as the Archean gave way to the Proterozoic eon, lasting from 2.5 billion to half a billion years ago. The earliest cells on Earth had been relatively simple affairs. Called prokaryotes, they include modern-day bacteria. The first prokaryotes lived by breaking down complex molecules into simpler structures (basically fermentation). The evolution of early forms of photosynthesis had, however, given some prokaryotes the ability to draw energy directly from sunlight. These were the earliest forms of photosynthesis, whereby cells use sunlight to generate food.23
By the beginning of the Proterozoic eon, life had learned new, more efficient photosynthetic strategies. Some of these came from the development of a wider range of internal machinery, like a cellular nucleus to hold the genetic blueprints of the cell. The emergence of these nucleus-bearing eukaryotic cells changed life’s trajectory on the planet. With the addition of new forms of photosynthesis, more energy became available to cells, allowing them greater flexibility and adaptation. The first multicellular organisms appeared during the Proterozoic, as life began to experiment with the division of labor. Cells specialized into different forms that worked together. Left without the larger organism, however, these specialized cells would die.24
Along with the changes in life, the planet itself was changing. During the billion-year-plus stretch of the Proterozoic, the first cratons grew into full-sized continents. Eventually, the slow movement of the Earth’s crustal plates (plate tectonics) drew them together to form a supercontinent, a vast landmass called Rodinia. Other supercontinents would form and break apart over the course of Earth’s history. Each would change the planet’s climate by altering global ocean circulation and resetting patterns of rock weathering and CO2 cycling.25
Perhaps the most important climate shifts to come during the Proterozoic were the first periods of near-total glaciation. At least four times during this eon, changes in the concentrations of atmospheric greenhouse gases plunged planetary temperatures into the freezer. From the poles all the way to the equator, the entire planet may have become locked in miles-thick layers of ice.26 Seen from space, this snowball world would have appeared as a mottled and cracked Ping-Pong ball with no large expanses of open blue water.
Thus, the Earth was once a snowball world of endless ice.
For all the changes Earth experienced, none was more remarkable or mysterious than life’s sudden burst of creativity just after the Phanerozoic eon began 540 million years ago. Across a remarkably short span of geological time, evolution threw itself a party. What began as still-simple multicellular life rapidly diversified into an orgy of new forms and new species. In just fifty million years, evolution produced all the basic structures that mark life on Earth today. Called the Cambrian Explosion (it occurred during the Cambrian geologic era), it was an evolutionary acceleration on a scale never seen before or after.27
It was only after the Cambrian era that all the “prehistoric” worlds we know from popular fictions arose. There was the Carboniferous era three hundred million years ago, with its vast swamp forests. Those forests eventually became the coal beds we’ve used to power our project of civilization.28 There was also the Jurassic era, dominated by the huge dinosaurs that live on in movies and the dreams of little kids. And finally, there was the more recent cycling of ice ages and interglacial periods, during which we humans appeared and eventually flourished.
The Earth swung back and forth between many versions of itself during the fecund eon of the Phanerozoic. But of particular interest to our own age are the periods when the planetary thermometer rose to fever levels.
Fifty-five million years ago, the supercontinent called Pangaea began splitting apart. The volcanism that accompanies plate tectonics went into overdrive, dumping CO2 into the atmosphere far faster than it could be removed by natural feedbacks. Global average temperatures rose fourteen degrees Fahrenheit above what we experience today. Called the Paleocene-Eocene Thermal Maximum, the result was a planet almost without ice.29 Temperatures in Greenland, where a future Soren Gregersen would endure his subzero glacial summers, stayed at a balmy 70 degrees Fahrenheit.
Thus, the Earth was once a jungle world, a sweltering hothouse planet devoid of snow.
Given the scale of the Earth’s changes between one mask and another, the next question we should ask seems clear. What force was powerful enough to drive our world’s dramatic transformations?
THE GREAT OXIDATION EVENT
The engineer asks Donald Canfield if he is claustrophobic. Canfield, a professor of ecology, has just squeezed himself into the cramped confines of Alvin, the world’s most famous deep-sea submersible. It’s a fall day in 1999 on a research ship slowly rolling in the Gulf of California’s blue waters.
“Claustrophobic? No, not at all,” Canfield says, lying enough to make them both feel better.
The engineer flashes him a knowing smile and says, “Good . . . whatever you do, don’t touch the red handle. It’s only for emergencies.”30 The hatch slams closed.
After an hour-long descent, Canfield is skimming along on the floor of the Guaymas Basin in the Gulf of California, more than fifty miles east of the Baja Peninsula and over a mile below the surface. The basin is a “spreading zone” where two of Earth’s continental plates are pulling apart.31 As the plates move away from each other, they carry the Baja Peninsula away from mainland Mexico at a rate of about one inch per year, the same rate as your fingernails grow.32 In between the spreading plates, new seafloor crust is constructed as hot magma upwells from deeper within the planet, cools, and then hardens into solid rock.
From the circular observing port cut into Alvin’s six-foot titanium crew capsule, Canfield gets his first view of the basin’s floor. Far from the well-lit upper ocean, it’s an alien world laid out before him.
“All around us,” Canfield recalls in his book, Oxygen, “We see the effervescence of hot [sulfur]-rich, hydrothermal waters percolating from the accumulating crust.” Boiling water, heated by the Earth’s internal fury, rises in dark columns from the vents. High-temperature geology is, however, only one facet of the otherworldly vision in front of Canfield. Remarkably, life is thriving here in the heat and the darkness. “Great mounds of Riftia tubeworms rise from the shadows swaying gently on expansive hills of gypsum crust,” he writes.33 The enormous tubeworms have no color—none is needed in this world of perpetual darkness.
Everywhere, Canfield makes out what appears to be fallen snow on the gypsum-crusted seafloor. What he sees, however, is not snow, but bacteria. The abundant microscopic creatures draw their energy from the heat and sulfur-based compounds spilling from the hydrothermal vents.34 Their ability to thrive in such an extreme environment is what allows the whole strange ecosystem laid out before Canfield to exist.
Canfield made this trip to the ocean floor to gain insights into the Earth’s past in terms of an alternative biochemistry. What he found at the bottom of the Guaymas Basin were hints pointing to versions of life that need no sunlight. These are, perhaps, vestiges of an early incarnation of the planet before its most significant transformational event: the rise of oxygen in the Great Oxidation Event.
“Try to imagine something so profound, so fundamental, that it changed the whole world,” Canfield writes. “Think of something so revolutionary, that it forever changed the chemistry of the atmosphere, the chemistry of the oceans and the nature of life itself.”35
After posing this question, Canfield surveys the critical moments in human history: the Great Plague, the Renaissance, and World War II. “These were important events,” he writes. “But their influence outside the human realm was small.” He then goes on to consider the extinction event sixty-five million years ago that killed the dinosaurs, and the one 250 million years ago that took down almost 95 percent of all animal species on the planet. Even those events pale in comparison to Canfield’s target. “Each of these major extinctions changed the course of animal evolution, but still, they did not fundamentally alter the fabric of life or surface chemistry of Earth.”36 What, he asks, did so completely transform the Earth? The answer to Canfield’s question turns out to be as simple as drawing a breath.
During Earth’s earliest eras, much of biology may have been powered by chemistry akin to what Canfield saw on his dive. By the middle of the Archean, however, at least some single-celled organisms had figured out how to tap a new and abundant energy source: sunlight. The first emergence of photosynthetic organisms in the form of what scientists call anoxygenic phototrophs (non-oxygen-producing sunlight eaters) was a major innovation in the history of life. Through the remarkable trial and error of evolution (and lots of time), some bacteria developed molecular light receptors. These were nanoscale machines that absorbed energy from the Sun and used it to power chemical reactions that popped out sugar molecules. Sugar, in whatever form, is the basic chemical battery for all the metabolic shenanigans cells need to stay alive.37
After a billion or so years of non-oxygen-producing photosynthesis, nature got very creative. Sometime in the late Archean, evolution produced a new version of photosynthesis that, for the first time, used water to drive its chemistry. Because water is superabundant on Earth, cells using this new kind of photosynthesis won out over the older forms. But these organisms—called cyanobacteria, or blue-green algae—did more than just multiply. Sucking in water, CO2, and sunlight, they also started spitting out molecules of oxygen as a kind of waste product of their activity.38 In this way, their innovative water-eating, light-powered, oxygen-producing metabolism led them to become the most powerful force in the history of the planet.
Over time, the activity of the cyanobacteria dumped so much oxygen into the oceans and atmosphere that the entire planet was forced to respond. The geologic record shows evidence of early “whiffs” where atmospheric oxygen levels increased by small amounts. But by 2.5 billion years ago, the fix was in. Across just a few hundred million years, the concentration of atmospheric oxygen increased by a factor of a million.
This was the Great Oxidation Event, or GOE. Ironically, the rise in oxygen was poison to the bulk of the life that existed at the time. Oxygen’s ability to bind with so many chemicals means it can quickly degrade the function of cells and kill them. But evolution figured out how to make lemonade out of lemons. It learned to work with oxygen’s juiced-up chemistry to create better, more energetic forms of life. Soon, creatures that breathed in oxygen had evolved. They used the element to power faster and more complex metabolisms.39 The big brain you’re using to read and comprehend these words would never have been possible without oxygen’s kick to evolution.
By the end of the GOE, the anoxygenic phototrophs, once the planet’s masters, had been forced into oxygen-free warrens, learning how to live in places like the fetid sulfur pits of Yellowstone or even deep in our stomachs. In this way, the new oxygen-breathing forms of life inherited the open sea and open sky.
The presence of oxygen in the atmosphere also allowed life to colonize the land en masse. Before the GOE, cell-damaging ultraviolet radiation from the Sun (the kind that gives you sunburn) streamed unremittingly through the atmosphere. Only in the oceans, below the surface, was life safe enough from UV light to form rich ecosystems. But with oxygen came the atmospheric ozone layer. Ozone is a gas, made up of molecules with three oxygen atoms, that forms high in the stratosphere. It’s a potent absorber of UV radiation. This ozone sunblock shield, which made the land safe for life, could not have formed without the rise in atmospheric oxygen.40
So, what does the GOE, with all its power and reach, teach us about the Anthropocene? It demonstrates that life is not an afterthought in the planet’s evolution. It didn’t just show up on Earth and go along for the ride. The GOE makes it clear that, at an earlier point in Earth’s history, life fully and completely changed the course of planetary evolution. It shows us that what we are doing today in driving the Anthropocene is neither novel nor unprecedented. But it also tells us that changing the planet may not work out well for the specific forms of life that caused the change. The oxygen-producing (but non-oxygen-breathing) bacteria were forced off the Earth’s surface by their own activity in the GOE.
So, from the GOE we gain insights that are themselves a turning of the wheel in humanity’s conception of itself and its place in the cosmos. We come to an idea that touches both the deepest levels of scientific consequence and the highest forms of mythic understanding. We come to the moment where the biosphere, and our place in it, can be fully imagined.
THE BIOSPHERE BEGINS
Scientists become famous for a lot of reasons. There are those like Einstein and Darwin whose visions shatter old ideas. Their names go on to live forever in the pantheon of genius. Then there are those like Carl Sagan and Stephen Hawking, both brilliant researchers, whose talents as writers allowed millions of non-scientists to understand the beauty and power of science. But how many people have ever heard of Vladimir Ivanovich Vernadsky? His name is far from a household word outside of his native Russia. But that obscurity is destined to change along with the planet.
It was Vernadsky’s ideas—and their genius—that heralded a new scientific conception of life’s planetary context. As we enter more deeply into the Anthropocene, we will find Vernadsky already there, waiting for us to catch up with him.
Vernadsky was born in 1863 in the St. Petersburg of Imperial Russia. His mother came from nobility; his father was a professor of political economy and statistics.41 Vernadsky’s parents were known for their devotion to democratic and humanistic ideals. From them, he inherited a fierce determination to live by those ideals, which was grafted onto a love of science. Across eighty-two years of wars, revolution, and acute political turmoil, Vernadsky did not waver in his devotion to scientific inquiry. And even at the greatest personal risk, he never wavered in working for the freedom to pursue scientific ideas, wherever they led.42
Vernadsky began his scientific work in the chemical study of minerals. Traveling across Europe in the late 1800s, he was keen to apply the most modern methods of physics to the study of rocks. His goal was to bring precision tools to bear on questions about the planet’s history. But even as Vernadsky was committed to exacting empirical studies, he was always more than a specialist. Across his career, he struggled to see how the whole emerges from the narrower stories scientists can unlock from the parts.
Russian scientist Vladimir Ivanovich Vernadsky.
In this way, Vernadsky built a solid, data-driven foundation for a new field called geochemistry, which unpacked Earth’s history by examining the microscopic composition of its physical constituents. Then Vernadsky went further. It wasn’t just geology and chemistry that were linked. In his eyes, biology also had to be brought into the planet’s story at a fundamental level, so he initiated a second field: biogeochemistry.43
Vernadsky was often critical of biologists for the way they treated “organisms as autonomous entities.” In his eyes, any individual species carried more than just an imprint of the environment within which it had evolved. Instead, the environment was shaped by the activity of life as a whole. As he put it, “An organism is involved with the environment to which it is [has] not only adapted but which is adapted to it as well.”
This attention to both microscopic and macroscopic views led Vernadsky to his most important addition to the language of life in the context of its planetary host. Building on discussions with the Swiss geologist Eduard Suess, Vernadsky proposed that the study of the Earth would not be complete without understanding the central role of life as a planetary force. Earth, in his view, cannot be truly understood without understanding the dynamics of its biosphere.
Living as we do after astronaut William Anders’s Earthrise, it’s hard to imagine that the biosphere could ever be a new or radical idea. But it was Vernadsky who gave the concept its scientific birth. It was Vernadsky who first clearly articulated what later scientists, studying everything from the Great Oxidation Event to modern climate change, would slowly—and with great effort—come to verify: Life was not just a patchy green scruff holding a tenuous position between rock and air; instead, it was a planetary power as important as volcanoes and tides. It was an active force shaping the complex multibillion-year history of the world. As Vernadsky wrote in 1926:
The matter of the biosphere collects and redistributes solar energy, and converts it ultimately into free energy capable of doing work on Earth. . . . The radiations that pour upon the Earth cause the biosphere to take on properties unknown to lifeless planetary surfaces, and thus transform the face of the Earth.44
Over the whole of his celebrated career, Vernadsky continued to modify and extended his concept of biosphere. Specifically, he saw it as a region—a shell—extending from below the Earth’s crust (the lithosphere) all the way to the edge of the atmosphere. Within this shell, the action of life dramatically changed flows of matter and energy.
Most important for our own moment, Vernadsky saw that the world-shaping powers of life were both ancient and ongoing. “Adjusting gradually and slowly, life seized the biosphere,” he wrote. “This process is not yet over.”
It’s the scale of his vision that makes Vernadsky so important to our story. Earth’s entry into the Anthropocene is, at one level, purely an issue of interacting planetary processes. Our entry into the Anthropocene, however, is different. For us, it’s also an issue of making meaning, of making sense of our place within the web of life that is also a force shaping the planet. Vernadsky envisioned a global view that achieved both. It was both scientific and mythic in scale, long before satellites and space missions could make such a global view of Earth tangible.
After his death in 1945, the limits of the Cold War meant it would take some time for Vernadsky’s radical view of life and its planetary reach to reach beyond Russia.45 But in time, Vernadsky’s vision did find its champions. As human culture was reshaped by its new space age, two scientists in particular would pick up Vernadsky’s biospheric vision and grow it into a full-fledged science.
BIOSPHERE RISING
James Lovelock was always the outsider’s insider. From the first radio set he cobbled together as a boy in England after World War I, Lovelock was an inventor of prodigious talent. Eventually, that talent drew governments and corporations to seek his help.
During World War II, Lovelock’s degree in chemistry took him into medical research, where he invented everything from precision airflow meters for studying the common cold to specialized wax pencils that could write on wet test tubes. This talent as a “maker” would eventually bring a degree of independence as his inventions drew a steady income. In the 1950s, Lovelock designed a cheap, portable device for detecting minute amounts of chemical contaminants. The patent was so valuable it allowed him to pursue science on his own terms, independent of an academic or government affiliation. But governments were still keen to sign him on to their projects.46
In 1961, Lovelock found himself at the same Jet Propulsion Laboratory in Pasadena, where Jack James and his team were exhausting themselves on the Mariner Venus mission. For Lovelock, the sprawling campus had the look of “a hasty airport with prefabricated cabins dotted over the hillside.” 47 JPL had paid for his trip to its nascent campus because they needed his aid in designing sensitive instruments for the new space missions. Eventually, Lovelock was put on a team proposing experiments to search for life on Mars.
Sitting through meetings where biologists laid out plans to detect Martian microbes, Lovelock found himself unconvinced. “The flaw in their thinking,” Lovelock recalls in his biography, “was their assumption that they already knew what Martian life was like. . . . I gathered the distinct impression that they saw it as like life in the Mojave Desert.” 48
But Lovelock, with an outsider’s perspective that would haunt him later, came at the problem from a different direction. “I think we need a general experiment,” he told the group, “something that looks for life itself, not the familiar attributes of life as we know it on Earth.” 49 Pressed by the program manager to propose experiments that looked for “life itself,” Lovelock was taken down a road that would lead him straight into the realms of Vernadsky’s biosphere.
Lovelock’s background in physics, chemistry, and biology led him to see the problem in terms of planetary atmospheres. He knew that life was keeping the air oxygen-rich. Take the biosphere away, and that oxygen would chemically combine with other compounds such that, if you waited long enough, the Earth’s atmosphere would become oxygen-free. Without life, it would return to a state of “chemical equilibrium” dominated by the CO2 released from volcanoes.50
Based on what he saw on Earth, Lovelock reasoned that life would always keep a planetary atmosphere in a state far from equilibrium. That meant the activity of life would constantly push on the planet’s chemistry. The biosphere’s continual resupply of oxygen, an element that would otherwise react away, was just one example of such a push.
Over the next two years, Lovelock continued to visit JPL and continued to work out the details of his atmosphere-as-life-detector experiment. But then, in September of 1965, a flash of insight showed him there was more to his idea than just an experiment.
In an office he shared with none other than a young Carl Sagan, Lovelock was poring over new data showing that the Martian atmosphere was dominated by CO2. Unlike Earth’s blanket of gases, Mars’s atmosphere was locked into the same kind of dead chemical equilibrium as that of Venus. A CO2-dominated atmosphere is exactly what you’d expect as the result of chemical reactions that were allowed to run their own course, like mixing a bunch of compounds together in a box and leaving the whole thing alone forever. It was at that moment that Lovelock saw the light.
“It came to me suddenly, just like a flash of enlightenment, that [for the chemistry of the Earth’s atmosphere] to persist and keep stable, something must be regulating [it].” The identity of this “something” came to Lovelock just as quickly as the question had. “It dawned on me that somehow life was regulating the climate as well as the chemistry. Suddenly the image of the Earth as a living organism able to regulate its temperature and chemistry at a comfortable steady state emerged in my mind.” 51
It was a powerful image. Lovelock saw the Earth as a single entity—“alive” in some sense—and regulating itself in the same way our bodies maintain their temperatures. Lovelock soon began fleshing out the details of his idea, looking for specific mechanisms life could harness to adjust conditions across an entire planet. As the work progressed, he realized he needed a name for the idea. He thought to call it the “Self-regulating Earth System Theory,” but a conversation with a neighbor, the novelist William Golding (author of Lord of the Flies), convinced him otherwise. Golding suggested Lovelock name the theory after the Greek goddess of the Earth, Gaia.52
There is some irony in the fact that Carl Sagan, who did so much for our concept of Earth in its cosmic context, would be present for the insight that gave birth to Gaia theory. Given that Sagan was never very supportive of Lovelock’s idea, it is even more ironic that he’d serve as midwife to the next crucial step in its development.
In the years following their divorce, the biologist Lynn Margulis almost single-handedly forced the scientific community to recognize the importance of cooperation, rather than just competition, in evolution. Her theory of endosymbiosis demonstrated how the tiny chemical-processing plants in our cells called organelles had once been independent organisms. Margulis proved that organelles—like mitochondria, for example—had been absorbed into larger bacteria billions of years ago to form a cooperative, symbiotic whole. This symbiotic evolution was likely the origin of the eukaryotic (nucleus-bearing) cells that transformed life’s trajectory during the Archean eon.53
In the early 1970s, Margulis had become interested in the question of atmospheric oxygen and its microbial origin. When she asked her ex-husband, Carl Sagan, if he knew someone who might be good to talk with about the problem, he suggested Lovelock. From this unlikely introduction, Lovelock and Margulis began a collaboration that fully defined the Gaian concept of life as a self-regulating planetary system. Where Lovelock brought the top-down view of physics and chemistry, Margulis brought the essential bottom-up view of microbial life in all its plentitude and power.54
The essence of Gaia theory, as elaborated in papers by Lovelock and Margulis, lies in the concept of feedbacks that we first encountered in considering the greenhouse effect.
The temperature of the human body always hovers around 98.6 degrees Fahrenheit. That’s what is known as a steady state. At your death, your body drops back to room temperature. That’s equilibrium. The same ideas can be applied to the oxygen in the atmosphere. The current levels of oxygen are held in a steady state by chemical reactions driven by the presence of life. But how does life keep the oxygen levels steady? We’ve already seen how photosynthetic bacteria gave Earth its oxygen-rich air. But why did oxygen levels rise up to 21 percent, and no further? This is an important question, because if the concentration of oxygen in the air were to climb as high as 30 percent, the planet would become a tinderbox. Any lightning bolt would trigger fires that wouldn’t stop. So, what kept oxygen levels from rising above this dangerous threshold? To answer that question, Lovelock and Margulis turned to the idea of feedbacks.
In their Gaia theory, Lovelock and Margulis argued that life as a whole exerted global negative feedbacks on the planet. Those feedbacks had kept the planet in a series of long-term steady states over its history that were always optimal for making the planet habitable and inhabited. In other words, life kept the planet cozy for life. If, for example, oxygen levels rose too high, then the increased oxygen would, itself, trigger blooms of microorganisms whose biochemistry would lead to those levels being drawn back down. It was a very big idea indeed.
Lovelock and Margulis were offering a scientific narrative whose ties to the scale of world-building myth were explicit. It was Vernadsky on steroids, a vision of planetary evolution where life was not just a force, but a force with its own kind of intention. But just because an idea is big and beautiful doesn’t mean it’s true. In particular, with the all-important idea of intention—meaning life’s intention with its Gaian feedbacks—the two scientists opened a Pandora’s box.
THE BIOSPHERE BOUND
Oberon Zell-Ravenheart (whose given name is Timothy Zell) never met a New Age idea he didn’t embrace. He is a pagan and a shaman. A fully ordained priest in the Fellowship of Isis, he also finds time to work as an initiate in the Egyptian Church of the Eternal Source. Zell-Ravenheart is also a Gaian, and that, in a nutshell, is why so many scientists hated Lovelock and Margulis’s big, beautiful idea.
Early on, Gaia found itself scorned as a scientific theory by scientists but wildly popular in the larger culture. As historian and philosopher Michael Ruse puts it: “[The public] embraced Lovelock and his hypothesis with enthusiasm. People got into Gaia groups. Churches had Gaia services, sometimes with new music written especially for the occasion. There was a Gaia atlas, Gaia gardening, Gaia herbs, Gaia retreats, Gaia networking, and much more.”55
Gaia theory came along just as the environmental movement and post-’60s New Ageism were going mainstream. In 1979, nuclear power became a national issue thanks to the partial core meltdown at the Three Mile Island generating station near Harrisburg, Pennsylvania. The pollution-driven evacuation of Love Canal in Upstate New York became the poster child for what environmental degradation looked like. Gaia theory, with its evocation of Earth as a single living organism—a vast planetary mother—channeled popular ecological concerns with an alternative vision of humanity’s place in the scheme of things.
Many scientists pounced on Lovelock and Margulis for promoting the equivalent of snake oil. As microbiologist John Postgate, a fellow of the Royal Society, put it: “Gaia—the Great Earth Mother! The planetary organism! Am I the only biologist to suffer a nasty twitch, a feeling of unreality, when the media invite me yet again to take it seriously?”56
The real problem with Gaia theory for many scientists was the issue of teleology. It’s a hallmark of biology that evolution that has no purpose, direction, or goal (telos is the Greek word for “goal”). The idea that the biosphere was somehow manipulating the chemical and physical conditions on the planet for its own good seemed inherently teleological (that is, goal-oriented). It smacked of intention, and evolution doesn’t have intention.57
Lovelock and Margulis were unbowed in their defense of Gaia. In response to critics who claimed their proposed feedbacks were nothing more than fantasy, Lovelock produced his now-famous Daisyworld model. Developed with mathematician James Watson, the Daisyworld model used a simple set of equations to describe a planet with two species of daisies (black and white) and a gradually brightening sun. The solutions to the equations showed clearly how feedbacks from the daisies (the black ones absorbed sunlight, while the white ones reflected it) could naturally keep the planet at a steady temperature even as the sun heated up. It was a tour de force of representing a complex idea with simple math in the service of proving an essential point. As Lovelock put it, “Daisyworld keeps its temperature close to the optimum for daisy growth. There is no teleology or foresight in it.”58
And Lovelock and Margulis made it clear, they were not claiming the planet should be considered alive in any true sense of the word. New Age Gaian Mother Earth ceremonies notwithstanding, Lovelock and Margulis were ultimately arguing for the central role of the biosphere in planetary evolution. They were picking up where Vernadsky left off, and putting in more science.
With the publication of the Daisyworld model in 1983, the tide, at least partially, began to turn. Biospheric feedbacks were recognized as an essential part of planetary laws of operation. These feedbacks represent the definition of how to think like a planet, and researchers embraced the biosphere’s central role in their studies of the Earth. But in the process, the name “Gaia theory” was dropped and replaced with the less contentious “Earth system science.” While the concept of self-regulation remained contentious, researchers now knew that the linkages between the biosphere, atmosphere, and other systems were so tight that they had to be considered together as a single entity. The adoption of the Earth system paradigm represented its own revolution in how we think of planets, and today it forms the cross-disciplinary foundation for all researchers trying to understand climate change.59
As these studies of Earth system science were extended to include the planet’s past, a crucial new idea would be added to the researcher’s lexicon. Building on Vernadsky, Lovelock, and Margulis, a new generation of scientists began speaking of a “coevolution” between life and the planet. That word, coevolution, would help rewire astrobiology. Life could no longer be isolated from the planet that gave it birth. Instead, a planet could be deeply transformed by the life it births, including when that life goes on to create its own globe-spanning civilization. Thus, within that single term, coevolution, lay the seeds of a new story waiting to be told about humanity and our Anthropocene.
