Who controls the past, controls the future. Who controls the present controls the past.
- George Orwell/1984.
In indirect fashion, global warming's doing the same thing as the world's ice and the history it holds is going away, something akin to how Snowball Earth erased a billions years of history as per research described by paleoclimatologist Summer Praetorius in a Nautilus articled titled The Great Forgetting.
In geology, an “unconformity” represents an aberration in the normal accumulation of sediment, a glitch in the record-keeping of Earth’s history. “A stratum of amnesia in the geological record, where overlying rock, significantly younger than what lies below, represents some break in an otherwise continuous story of formation,” is how writer and poet Kim Stafford defined it.2
The longest lacuna in Earth’s history is known as the Great Unconformity. It represents a temporal gap ranging from a hundred million years to over a billion years, depending on the location. It’s visible in the Grand Canyon as the boundary between the Precambrian Vishnu Schist and the Cambrian Tapeats Sandstone, between which there is a billion years of missing time between about 1,600 and 600 million years ago. Looking at this line in the strata, it is hard to fathom all that would have conspired across that vast gulf of time, for which there is simply nothing. If it were instead to have been the last billion years that was erased, it would obliterate the entire history of complex life. No trace of a single animal having ever walked the land. No dinosaurs, no whales, no humans, no pyramids.
How does a billion years go missing? The Great Unconformity has long been a geological mystery, in no small part because it is a challenge to reconstruct history when records of history are missing.
It turns out, ice sheets are good shredders. Recent research3 suggests that the Great Unconformity may be a result of Snowball Earth—when the planet descended into deep cold (about 700 million years ago), and glaciers covered most of the land. A billion years of history was ground down by ice and bulldozed into the seafloor, where it was subducted into the Earth’s mantle and recycled into magma, ready to be remade into new history—albeit with a few hidden remnants of the past stored safely away in subterranean crystals.
Presently, the notion of history's going away as we speak ...
But the world’s glaciers are now hemorrhaging their histories. Mountain glaciers are peeling at their edges like smoldering paper, while Greenland sweats off a million tons a minute.8 On bad days, it is enough water to submerge entire states.9 Between 1994 and 2017, 30 trillion tons of ice have been lost globally,10 and things are just starting to heat up. In August of 2021, it rained on the summit of Greenland. A melt layer will form to mark the event—a dire sign for the top of an ice sheet. Coastal areas along Greenland have become too slushy to drill into, preventing scientists from retrieving ice cores in those regions, rendering its history inaccessible.
In essence, Heat makes easy work of forgetting.
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