Dawn of the Heliocene

I was born on the summer solstice in an age without a name.

My parents were born in a previous geological epoch. Six unknowing months before the start of the Great Depression, my father arrived. His given name was Richard, but as soon as his hair came in, he was Red. He would become a keeper of junkyards—overgrown lost worlds of relic chariots. I was a fledgling junk collector, sent out to prod garbage dumps for lost treasures: no plastics allowed, just wood or metal. My mother was born on VE Day, her bones still untainted by the nuclear bombs that would come a few months later, ushering in a new epoch. Her first name was Margery but everyone called her Eliza.

It was less than a century ago that my parents were born in the Holocene—the “recent whole” that constitutes the interglacial epoch that commenced 11,720 years ago.¹ In the geological time scale, an epoch represents a major shift in Earth’s climate—longer than an age, but shorter than a period, era, and eon.² The root ‘cene’ comes from the Greek Kainos, meaning recent or new. Some geologists think the Holocene has come to a close and a new epoch has arisen, brought about by human perturbation to the Earth’s carbon and nutrient cycles.³ The Anthropocene is the proposed name,⁴ to acknowledge the force that has derailed the Holocene from its previous climate trajectory.⁵ While “Anthropocene” is already in wide use, it has not been ratified into the geological time scale, which first requires clear documentation of a time and place to mark its origins. Luckily, this has bought us some time to reconsider the right name for our unfolding epoch.

My name was supposed to be Kate. Planned for nearly 20 years—a pact between my mother and her college roommate to each name their first daughter Kate. My mother’s friend upheld her end of the bargain, but then there I was, a solstice changeling, revealing my true name. I am glad they listened. “You look like your name” is the comment I get when first meeting someone. It always makes me wonder what I might have looked like had my name been Kate—how much we shape the name or it shapes us.

As a junkyard kid, I was surrounded by things people had given up on: decaying boats, milk trucks, acres of American classics done-in by acceleration of one kind or another. But the junkyard was a beautiful place, blooming daily into unexpected entanglements and recombinations: saplings sprouting from convertibles, oak trees wearing bucket-seat skirts, rust paintings as rich and textured as oil, sprawled over every hood and door. I learned to love the art of the search, the stories emerging from decomposing seats, revealing lost glasses and keys. It is a habit that persists, a form of meditation even, to sort and sift through beach debris, clover patches, and now as a paleoclimatologist, the ancient sand under my microscope, taking delight in finding the perfect foraminifera or a glittering quartz gemstone dropped into the sea by a disappearing iceberg thousands of years ago.

My first car took two years to build. It was made from the dismembered limbs and organs of five dead cars, which I welded and painted until it was a metallic jade beauty with two compass ornaments that allowed me to steer my way off the junkyard in wild fish-tailing skid marks down the back roads of the Catskill foothills.

If we squander this moment, we will all be back in the junkyard soon enough.

I can’t know how my life would be different had my parents given me another name. But I do know that I always felt my solstice namesake was a totem I carried in my pocket, an emblem of the elemental that preceded the coordinates of circumstance, a permission I gave myself to shape-shift.

The Anthropocene may seem like the right name now, but it is tethered too tightly to our present circumstance, defining our epoch by what is below us rather than ahead of us. Other names have surfaced to capture how we’re remaking our environment. They include the Homogenocene— the age of homogenization of plant and animal species due to invasion and global spreading⁶; Myxocene—the age in which the oceans will become dominated by jellyfish and microbial slime⁷; Plasticene—the age of plastics⁸; and Pyrocene—the age of fire.⁹ While all hold truths and warnings, most conjure images of the worst of what might lie ahead: plastic and jellyfish-clogged oceans, firestorms whipping up their own weather systems, invasive species decimating biodiversity and igniting zoonotic pandemics, while humans stand at the helm, steering us toward a hothouse wasteland, wavering on the horizon like a Fata Morgana.

Before it comes time to engrave it in stone, to nail in the golden spike of our new epoch, we should reconsider the name we give our future—how it may subtly steer its trajectory. To choose the right name, we must first find the birthplace of our new epoch, which is the same thing as finding the deathplace of the Holocene.

The Global Boundary Stratotype Section and Point (GSSP) is the location that marks a boundary in geological time. In nearly all cases, it is an exposed outcrop of ancient marine sediment that has a defining contact between two strata that represents a global environmental shift of prolonged duration. This is where the golden spike is driven—ground zero for a major course change in Earth history.

The golden spike for the Cretaceous-Paleogene boundary is in El Kef, Tunisia,¹⁰ but is more widely defined as the iridium layer associated with the dinosaur-killing asteroid impact, making it the most instantaneous boundary in the geological time scale. In the case of more recent boundaries, such as the Pleistocene-Holocene transition, it is not as easy to find an outcrop on land that documents the transition, so plumbing of paleoclimate archives is required. The GSSP for the start of the Holocene has been located at a depth of 1492.45 meters in the central Greenland Ice Sheet.¹

By most measures, the Holocene appears to have been a climatic paradise: not too cold, not too hot, and relatively stable overall, aside from an occasional large volcanic eruption and megadrought. That the development of agriculture and proliferation of human civilization has only occurred within the cradle of the Holocene’s mild and stable climate is widely considered no coincidence. But for all the promise this golden child of climate seemed to have, its course was cut short. Most ages last at least a few million years, but a mere 11,700 years after it began, the Holocene had been declared dead.

The story goes that at a geoscience conference in 2000, the Nobel Prize-winning atmospheric chemist, Paul Crutzen, declared in exasperation to his colleagues who were still referring to the current epoch as the Holocene, “We’re not in the Holocene anymore. We’re in the … Anthropocene!” Later that year Crutzen and Eugene Stoermer published an article outlining the case for the geological basis of the Anthropocene.⁴ This marked the turning point in the widespread recognition and consideration that humans had altered the planet enough to warrant a new geological epoch. But while it had become clear that the Holocene had ended, the precise date of its passing was still to be determined.

The detective story of homing in on the time and place of the Holocene’s death has involved a global search by a group of scientists known as the Anthropocene Working Group, carefully cataloging and considering various sedimentary archives, prodding sediments for clues, running forensics on the chemical signatures left in the soil.¹¹ The evidence has converged on who killed the Holocene. Culprit: humans. Date of death: 1950.

There are a number of reasons to lay the Holocene to rest at this particular date. 1950 is already the year used to define “present” in the radio-carbon time scale, making it a widely used reference point in geological timelines, so year zero would conveniently coincide with the beginning of our new epoch. But convenience is not the necessary criteria for marking a GSSP. It requires documenting strata.

Waste is just another word for wealth.

The mid 20th century was an inflection point in a number of profound chemical and stratigraphic changes in the Earth system. The list includes an increase in carbon dioxide and methane in the atmosphere, an increase in the use and deposition of fertilizers, plastic products, industrial fly-ash, and of course a great acceleration in human population growth and concomitant decline in biodiversity and natural habitat. The collective inflection of these variables has been labeled “The Great Acceleration.”¹²

In the cornucopia of chemical signatures that skyrocket in the mid 20th century, one rises to the top as the most promising global marker to define the boundary between the Holocene and Anthropocene: the radioactive spike associated with nuclear testing from 1945 to the early 1960s. Similar to the iridium layer at the Cretaceous-Paleogene boundary that marks the detonation of the 6-mile-wide asteroid, it is a signal that is both global and unambiguous in the events it represents. The chemical traces of nuclear testing can be found in ice sheets, lake bottoms, deep-sea sediments, and the bodies of living organisms, including our own.

That the detonation of nuclear bombs would mark the start of our new epoch is perhaps not the best harbinger of what is to come—much like starting the New Year with a hangover instead of a polar bear plunge.

And yet something else momentous happened in that same window of time. Something even more powerful than destruction. Humans reinvented a way to directly capture energy from the sun—previously the singular achievement of photosynthetic organisms. In 1950, in the suburbs of New Jersey, researchers at Bell Labs were busy making breakthroughs that paved the path for the first practical solar cells. In 1954, they unveiled the first silicon photovoltaics; the prototypes for solar cells widely in use today.

Viewed from the breadth of the geological time scale, one could mark this moment as a branch point in Earth history similar to the dawn of photosynthesis—life forever changing the trajectory of the planet by figuring out a way to intercept the high quality energy raining down from the sky. When cyanobacteria first cracked the code of photosynthesis 2.5 billion years ago, they flooded the atmosphere with oxygen and paved the way for multicellular organisms. Their invention is marked by layers of rust— banded iron formations—as iron reacted with the available oxygen. The Siderian, it’s called.

Most geological boundaries are like this: They start with disruption and evolve into complexity and stability over spans of time that dwarf the brief pains of their birth. The Paleogene began with the detonation of an asteroid a billion times more powerful than a nuclear bomb, wiping out 75 percent of all plants and animals on the planet. It would take years for the atmospheric fallout to cease and the sun to shine again,¹³ thousands for ocean chemistry to stabilize,¹⁴ and yet even shortly after this brutal annihilation, ferns were unfurling themselves within the battered landscape, mousy mammals were scuttling about, freed from the tyranny of their oversized predecessors, and in less than a million years, mammals were ballooning in size,¹⁵ hitting a stride that would carry them all the way to the present day.

In the 2.5 billion years since cyanobacteria first invented photosynthesis, nearly all of the energy available to life on Earth has been supplied by primary producers’ ability to convert solar energy into carbon bonds. All of history’s exotic characters have been knitted from an intricate patchwork of photosynthetic scraps, downcycling solar energy into stranger and stranger outfits until its reworking potential is exhausted into a formless pile of heat waste.

In a steady state, most of the energy captured by photosynthesis is used up by the furnace of respiration and metabolism burning on Earth’s surface by its infrared layer of life. This means all the energy available to support life was historically bounded by the supply provided by photosynthetic organisms. If primary producers captured one percent of the incipient solar energy, then those were the chips on the table to get passed around.

But rarely are things ever in a true steady state, so at times in the geological past, some of this energy has slipped through the cracks, sealed off in anoxic basins—dead zones where life can’t go to access this energy. All else being equal, this occasional leaky faucet of carbon would have created a slight deficit in the energy available to life in the past. In other words, larger dead zones would have made for smaller life zones.

I was a fledgling junk collector, sent out to prod garbage dumps for lost treasures.

Over time, this slow burial of organic matter accumulated into storage strata of ancient sunlight, well hidden in the dark cloak of carbon. But humans have a long history of piracy, so this ancient treasure did not stay hidden for long. The unique ability of humans to pry open the Earth and excavate the mass carbon graves of millions of years ago has created an energy surplus unheard of in the billions of years prior. And just like buried treasure, those who get a hold of it first are the ones to profit on past deficit.

Since the Industrial Revolution, we have already burned up an entire Earth-equivalent of biomass.¹⁶ In the past, we were harvesting the fruits of our nearby acreage. Now we are consuming entire Earths. It is no coincidence that such unusual surplus has been accompanied by such spectacular waste. Under normal circumstances with limited energy to go around, life would never be so sloppy to discard the byproducts of this energy without first licking the plate clean. Waste is just another word for wealth.

Not surprisingly, the vast waste deposits produced during the Great Acceleration figure prominently in the search for a suitable stratigraphic section to place the GSSP that will mark the start of the Anthropocene. The Fresh Kills Landfill on Staten Island is one such example discussed in a paper by the Anthropocene Working Group.¹⁷ “Covering some 8.9 million m², up to 70m high, and containing ~150 million tons of municipal waste, it may be the largest human-engineered formation in the world. It was opened in 1948, with a peak influx of garbage reaching 29,000 tons per day and closed in 2002 CE, the last debris being from the 9/11 event in 2001 CE.”

Nuclear bombs, industrial fly ash, plastics, and garbage dumps with the wreckage of terrorism contend to mark the start of our new epoch. Is it no wonder that we have such an uninspiring list of dystopia-cenes to choose from?

While it is true we find ourselves swimming in a shallow sea of our own waste, our lifeline is that not all of this waste has been wasted. Our unusual energy surplus has made it possible to reinvent the wheel of solar capture and drive past the limitations previously imposed on life, which had been almost exclusively beholden to photosynthetic energy capture.

Every year the sun pelts Earth with over 5,000 times our annual global energy demands.¹⁸ Our challenge now is to figure out how to build buckets big enough to collect from the firehose. Renovation will always incur wreckage, but the key is to rebuild smarter each time, to find the path of persistence. We could choose to keep digging up sunlight from the past, hold fast to our archaic roots, like pirates fighting over ever smaller and more elusive caches of treasure, or we could embrace our new ability to capture energy straight from the sky, paving a path out of this mess we’ve made.

Like all geological boundaries, it will take time to find our way to stability. The transformation of our energy infrastructure and waste management systems, as well as the transition toward balance with the biosphere will require a full spectrum of solutions.¹⁹ These solutions will not only save trillions of dollars in the long run, but will allow us an opportunity to reconfigure in cleaner, more equitable, efficient, and adaptive ways.

There will be vestigial tailbones and dangling dewclaws for some time to come, but the point is to set our sights for our best selves and not our worst. If we name ourselves as the center of rotation, we are placing the nail in our coffin; we are writing the end into our beginning. It is our anthropocentrism that got us in this mess to begin with. We shouldn’t confuse the power we currently wield to destroy Earth systems with the power it takes to build stable networks. Our perseverance lies in recognizing our reliance on the Earth system, not our dominance of it.

Like Copernicus’ heliocentric model of the solar system, sometimes revolutions occur by a simple shift in the axis of rotation. I propose we call our new epoch the “Heliocene,” meaning “new sun.” Heliocene represents the moment when another life form figured out a way to tap into the potential of the sun, and adopts a name for our epoch that better centers humans within the spheres that hold us.

The evidence has converged on who killed the Holocene. Culprit: humans. Date of death: 1950.

The development of solar cells perfectly corresponds to the boundary already deemed most appropriate to mark the transition between the Holocene and our new epoch. This represents a revolutionary shift in our ability to capture solar energy in real time rather than being dependent on solar energy of the past. We can still adhere to all of the same stratigraphic markers under consideration by the Anthropocene Working Group in defining a GSSP,¹⁶ but we can align our prevailing epoch with the invention that will lead to our persistence rather than our demise.

There is no requirement that the names of geological periods correspond to the contents of their strata. The Paleogene means “ancient born”; it is not called the Astergene (“star born”) for the extraterrestrial disturbance that started it. The most recent epochs form a continuum from “old new” to “newest new,” and ages are typically named after the place in which they are defined. But in the 4.6 billion years of Earth history, all sliced and diced, we never once stopped to acknowledge the nuclear furnace in the sky setting it all in motion, fueling the perpetual turnover and transformation of life on Earth. The earliest Earth is called the Hadean, after Hades; perhaps then it’s fitting that we name the future Earth for the upper world, the world of the living.

The boundary at 1950 marks a turning point. Geologically speaking, we are still standing at the base of this horizon—different paths stretching out in front of us. The choice is as simple as this: fusion or fission, construction or destruction. We can be sledgehammers, prying apart organic molecules and heavy uranium atoms, eviscerating the Earth for products forged in supernovae, or we can be builders, capturing the fusion energy of the sun to construct support systems that will stand the test of time. If we squander this moment of energy wealth, creating heat waste instead of structure, we will all be back in the junkyard soon enough.

This is not an attempt to whitewash our waste, to bury the toll that humans are taking on the planet right now. It’s important to recognize the truth of our impacts, to take stock of the enormous destruction we have reaped on this planet’s biodiversity and climate. We can rightly draw this line in the strata, marked by our global-scale perturbations and pollution, but we don’t have to continue on this path. We don’t have to box ourselves in to our present limitations.

In the same way my mother thought she knew what she would name me before I was born, I thought I knew where I would bury her before she died. She already owned a burial plot that had a tombstone engraved with her name and birth date. It had been a gift from a partner taken up after my father. He couldn’t quite capture her in life, so he tried to secure her company in death by buying her the plot next to him and having it engraved in stone. “A thoughtful gift” she once told me. But there I was, days after her death, staring at her name on the tombstone: Eliza Praetorius, May 8th, 1945 –

That trailing dash—my responsibility to answer it. I couldn’t bring myself to engrave the ending, to mark her boundary, to reel her in. She felt bigger than that 2×8 rectangle of soil, so I turned her into ash and fed her to a sapling apple tree in the foothills of the White Mountains in Maine. Snow-smothered twiggy branches in winter, glossy apples in September at my uncle’s house, packed in backpacks for granite hikes, an unanswered dash in a quiet graveyard in the Catskills.

In 1954, The New York Times ran an article lauding the invention of solar cells as potentially marking “the beginning of a new era, leading eventually to the realization of one of mankind’s most cherished dreams—the harnessing of the almost limitless energy of the sun for the uses of civilization.”²⁰ Maybe an era is a bit too optimistic for now, but we can at least start with an epoch. Let’s nail it in: The Heliocene, 1950 –

Summer Praetorius is a paleoclimatologist who uses marine microfossils to study changes in the oceans and climate of the past.

References

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2. Cohen, K.M., Finney, S.C., Gibbard, P.L., & Fan, J.-X. The ICS International Chronostratigraphic Chart. Episodes 36, 199-204 (2013; updated).

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4. Crutzen, P.J. & Stroermer, E.F. The “Anthropopcene.” The IGBP Newsletter 41, 17-19 (2000).

5. Kaufman, D., et al. Holocene global mean surface temperature, a multi-method reconstruction approach. Scientific Data 7:201 (2020).

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7. Attributed to Pauly, D. Peak Fish and the Age of Slime (2011).

8. Stager, C. Deep Future. The Next 100,000 Years of Life on Earth Thomas Dunne Books, New York, NY (2011).

9. Pyne, S. The fire age. Aeon (2015).

10. Molina, E., et al. The Global Boundary Stratotype Section and Point for the base of the Danian Stage (Paleocene, Paleogene, “Tertiary”, Cenozoic) at El Kef, Tunisia—Original definition and revision. Episodes 29, 263-273 (2006).

11. Zalasiewicz, J., et al. The working group on the Anthropocene: Summary of evidence and interim recommendations. Anthropocene 19, 55-60 (2017).

12. Steffen, W., Broadgate, W., Deutsch, L., Gaffney, O., & Ludwig, C. The trajectory of the Anthropocene: The Great Acceleration. The Anthropocene Review 2, 81-98 (2015).

13. Vellekoop, J., et al. Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary. Proceedings of the National Academy of Sciences 111, 7537-7541 (2014).

14. Henehan, M.J., et al. Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact. Proceedings of the National Academy of Sciences 116, 22500-22504 (2019).

15. Lyson, T.R., et al. Exceptional continental record of biotic recovery after the Cretaceous-Paleogene mass extinction. Science 366, 977-983 (2019).

16. Bar-On, Y., Phillips, R., & Milo, R. The biomass distribution on Earth. Proceedings of the National Academy of Sciences 115, 6506-6511 (2018).

17. Waters, C.N., et al. Global Boundary Stratotype Section and Point (GSSP) for the Anthropocene Series: Where and how to look for potential candidates. Earth-Science Reviews 178, 379-429 (2018).

18. Smil, V. Energy: A Beginner’s Guide Oneworld Publications, London, United Kingdom (2017).

19. Hawken, P. (Ed.) Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming Penguin Books, New York, NY (2017).

20. Vast power of the sun is tapped by battery using sand ingredient. The New York Times (1954).

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