Earth Has Been Many Planets

NASA Earthrise Photo


“There have been many planet Earths” says astrophysicist Adam Frank who talks about climate change from an astrobiological lens. Frank’s observation mirrors author Peter Brannen’s lens in that if 100 million years of Earth’s geological history, a span almost 10 times as long as all of recorded human history, can easily wear the Himalayas flat, what chance will San Francisco or New York have of surviving a new geological epoch of our own making: the Anthropocene.

“Whereas some epochs in Earth history stretch more than 40 million years,” writes Brannen, “this new chapter started maybe 400 years ago, when carbon dioxide dipped by a few parts per million in the atmosphere. Or perhaps, as a panel of scientists voted earlier this year, the epoch started as recently as 75 years ago, when atomic weapons began to dust the planet with an evanescence of strange radioisotopes”.


Mars-like Temperatures

In 1959 the logic of the Cold War led the US government to build a military base and a scientific laboratory right in the middle of Greenland –a giant ice slab where 700,000 square miles of glacier rise a mile and a half above sea level where temperatures plummet to a Marslike –70 degrees Fahrenheit. Winds routinely sweep across its barren plains of snow at 125 miles per hour.

“Day the Earth Changed” –Unveiled by a Young 31-Kilometer-Wide Greenland Crater

Powering the base required a $5 million portable nuclear reactor that the military dragged out across the ice sheet. 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.Taken together, building Camp Century foreshadowed a space-age effort –one that would achieve an epic breakthrough equal to 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 of which transformed our understanding of astronomy and planetary science.

Earth Reimagined

In the decades after World War II, writes Adam Frank in Light of the Stars: Alien Worlds and the Fate of the Earth, “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.”

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. Warfare is an feature of the human footprint, with a history of military campaigns done in by weather from Napoleon to Hitler’s Russia campaigns. Just as the funding for the exploration of space was opened by the Cold War, observes Frank, the Earth’s climate and its history had also become a military concern.

Our history of farming and cities, writing and machine building, observes Frank, “fits entirely within the Holocene: the current ten-thousand-year-old interglacial period. 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.

Beyond the Anthropocene -“A Mere Blink of the Geologic Eye”

“Under the auspices of the US Army’s Cold Regions Research and Engineering Laboratory, Camp Century’s drilling operation gave scientists that record hidden in the yearly strata of snowfall, forming a kind of frozen layer cake with each layer a record of that year’s climate. Within each layer of ice was a chemical marker that served as a proxy thermometer going back thousands of years revealing a period of roughly constant temperature stretching back eight thousand years, the Holocene, the time during which human civilization had been born and thrived but also exposing periods of rapid climate change that presented researchers with a warning the importance of which they could not yet understand that the planet we know today is not the Earth that was.”

The Point of No Return -Scientists Compare Current Climate Change to Geologic Past

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 starkly different from the iconic Earthrise photograph taken by William Anders during the Apollo 8 mission in 1968 or the global water-world of the Archean eon that lasted from 4 billion to 2.5 billion years ago when life based on the biochemistry of self-replicating molecules called DNA spread across the world.

Earth has been Many Planets

“Our world has been many planets in the past,” concludes Frank. “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.”


The beginning of the Anthropocene is a hard one to pin down

Perhaps, observes Peter Brannen reflecting on the lesson of Camp Century, “we’re at the dawning of the ‘Quaternary Anoxic Event’ or, God forbid, the ‘End-Pleistocene Mass Extinction’ if shit really hits the fan in the next few centuries. But please, not the Anthropocene. You wouldn’t stand next to a T. rex being vaporized 66 million years ago and be tempted to announce to the dawning of the hour-long Asteroidocene. You would at least wait for the dust to settle before declaring the dawn of the age of mammals.

The Last Word –Timothy Wootton, Professor, Evolutionary Biology at the The University of Chicago

“The beginning of the Anthropocene is a hard one to pin down. I know the geologists are busy arguing about how to define it and whether it even exists. Since epochs are defined geologically, I suppose that some event that is/will be geologically detectable in the distant future would be appropriate as a benchmark, even if it is not directly connected to the root causes.  As far as events, I would say large-scale mechanized use of coal would be my preferred choice, as it connects to population expansion, habitat destruction, and the onset of unsustainable carbon mining for energy, plus it likely has a geological signature (higher soot layer in the sediments).  Atomic radiation would be a geologically detectable signal but really is not the major driver of the changes generally viewed as being characteristic of the Anthropocene.  The advent of the Bosch-Haber process for nitrogen fixation might also be a candidate, as it might have a geological signature and contributed to the green revolution. One could make an argument for other criteria that are perhaps geologically more ephemeral, such as the advent of agriculturally-based societies, which connects to massive habitat change and which imposes signatures on historical ecosystem records, such as coral reefs, several hundred years before widespread coal mining.  One might even argue for spear technology at the end of the Pleistocene, as this involved geological evidence for human destruction of the Pleistocene megafauna, if we were to define the Anthropocene as widespread impact of humans, but we already have an epoch designation for that, I suppose.”

Timothy Wootton and Peter BrannenFrank, Adam. Light of the Stars: Alien Worlds and the Fate of the Earth (p. 100). W. W. Norton & Company. Kindle Edition, Google Talks, and The Atlantic 


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