They also note, “If a Pt-rich meteorite or comet impacted Earth, the target rocks would have become a melted mix of meteoritic and terrestrial material, and so should be Pt-enriched.”14
The coauthors therefore compiled geochemical data from eighty-six examples of such “impactites” from three major impact layers spread out over a period of more than two billion years. In every one of them they found elevated Pt abundances in a range including all the values in the Pt-rich YDB layers from around 12,800 years ago.15
FOLLOWING THE TRAIL OF CLUES
THE CORROBORATING EVIDENCE KEEPS COMING in.
When we met at Murray Springs in October 2017, Allen West told me about new CRG research that had identified an extended episode of extreme windiness, dustiness, and large-scale “biomass burning” at the onset of the Younger Dryas. He mentioned that “around 9 percent of the total biomass of the planet was on fire and destroyed within days or weeks of the YDB”—an astonishing statement—but I’d been so focused on other aspects of what he was saying that I hadn’t really considered the implications.
In February 2018 the Journal of Geology published the massive two-part study on which Allen’s off-the-cuff remarks were based. The title speaks for itself: “Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ~12,800 Years Ago.”16 CRG member Wendy Wolbach, professor of inorganic chemistry, geochemistry, and analytical chemistry at Chicago’s De Paul University, led the study, in which she was joined by Allen West and twenty-five other top researchers.17
Confirmation of the figure of 9 percent of terrestrial biomass comes on the first page, with the calculation that this would have meant that plant matter covering an area of no less than 10 million square kilometers would have been consumed by the inferno.18
To imagine a world in which 10 million square kilometers of vegetation is in flames is to imagine a world in which an area roughly twice the size of the Amazon rainforest is burning. That would be about the same as the entire area of China or the entire area of Europe or the entire area of North America in flames.
No matter how many separate wildfires there were, or how spread around the planet, a conflagration on this scale, hand in hand with the cascade of other disasters that marked the onset of the Younger Dryas, can only be described as hell on earth.
Once again, although records from lake sediments also provide vital clues, it is the Greenland ice cores, together with ice cores from other Arctic regions, that contain decisive evidence of the large-scale wildfires that raged across the world 12,800 years ago. This is not least because the upper (i.e., most recent) levels of these extremely long cores contain the traces of biomass wildfires that occurred and were recorded in the historic period, thus allowing identification and calibration of specific combustion aerosols, notably oxalate, ammonium, nitrate, acetate, formate, and levoglucosan, that serve as distinct signals—or proxies—of biomass-burning.19 Wherever an abundance of these combustion aerosols shows up in the ice cores we can be certain that they mark the atmospheric fallout from extensive wildfires, we can date those wildfires, and it is often possible to identify where on the planet they occurred.
Here are some important pieces of the Younger Dryas puzzle winnowed from the dense pages of the 2018 paper:
GISP2 Ice Core: Ammonium (NH4), a biomass-burning proxy, displays one of the highest peaks in the 120,000-year record in an interval dating to 12,830–12,828 years ago. This overlaps the platinum-rich interval dating to 12,836–12,815 years ago and coincides with the onset of the Younger Dryas.20
NGRIP Ice Core: A single high NH4 peak, traced to biomass burning across North America, begins at the YD onset. It is the largest biomass-burning episode from North American sources in the entire record.21
The GRIP concentrations of combustion aerosols began to increase sharply around 12,816 years ago, correlating with the GISP2 Pt anomaly (12,836–12,815 years ago). At the onset of the Younger Dryas, concentrations of oxalate and formate reached their highest known concentrations in the ~386,000-year core, with acetate abundances ranking among the highest in the entire core.22
These GRIP data reveal that massive wildfires occurred at the onset of the Younger Dryas, representing the most anomalous episode of biomass burning in at least 120,000 years and possibly in the past ~386,000 years.23
The Taylor Dome (Antarctica) ice-core record exhibits a small but distinct peak in NO3 that closely correlates with the Younger Dryas onset. The base of the Belukha, Siberia, ice core exhibits a major peak in NO3 [nitrate], indicating that a major episode of biomass burning occurred at the Younger Dryas onset.24
Several ice-core sequences (GISP2, NGRIP, GRIP, Taylor Dome and Belukha) confirm that the onset of the Younger Dryas was intimately associated with one of the highest and most pervasive late Quaternary peaks in each of NH4, NO3, formate, oxalate, and acetate. These peaks occurred synchronously with the abrupt cooling and other climatic effects marking the onset of the Younger Dryas episode.25
Investigation of “black mats” at nineteen sites in North America, Central America, Europe, and the Middle East: Peak abundances of black carbon (BC)/soot and other biomass-burning proxies were found in the Younger Dryas Boundary layers. … Concentrations of levoglucosan from within the black-mat layer in Ohio were around 125 times higher than those in the layer below it, signalling a significant peak in biomass burning.26
Analysis of charcoal in lake sediments from nine countries in South and Central America: One of the highest peaks in the record occurs at the Younger Dryas onset around 12,850 years ago.27
Analysis of charcoal in lake sediments from seven countries across Asia: There is a conspicuous peak in mean charcoal abundances at around 12,950 years ago (plus or minus 225 years) … followed by a sharp decline in biomass burning and then a peak at 12,400 years ago.28
A 24,000-year sequence recorded in a marine core from the Santa Barbara Basin, off the coast of California, exhibits the highest peak in biomass burning precisely at the onset of the Younger Dryas. … This anomalously high peak correlates with intense biomass burning documented from the nearby Channel Islands. … The peak also coincides with the extinction of pygmy mammoths on the islands and with the beginning of an apparent 600–800-year gap in the archaeological record, suggesting a sudden collapse in island human populations.29
A marine core from the western Pacific, 1,500 kilometers north of Papua New Guinea, provides a biomass-burning record spanning a period of 368,000 years. This core is unusual in providing a record not only of charcoal but also of black carbon, which includes AC/soot. The core exhibits a high black-carbon peak spanning the period between 13,291 and 12,515 years ago and overlapping the Younger Dryas onset at around 12,800 years ago. In addition, the YDB peak in black carbon coincides with an above-average charcoal peak at around 12,750 years ago.30
Evidence from widely separated ice records and sediment records demonstrates that a major, widespread peak in biomass burning occurred on at least four continents at the warm-to-cold transition marking the YD onset. This peak is synchronous with the cosmic-impact layer at the Younger Dryas Boundary as recorded by multiple impact-related proxies, including peak abundances of platinum, high-temperature microspherules, and meltglass.31
In summary, the earth and all life upon it endured and was devastated by what can only be described as a globally distributed firestorm at the onset of the Younger Dryas around 12,800 years ago. In this planetary debacle, 10 million square kilometers of trees and other plant matter burned.
To put that in perspective, the United Kingdom was in a state of traumatic shock in late June and early July 2018 after 4,942 acres of Lancashire moorland were consumed by wildfires. That’s an area of just 20 square kilometers, but firefighters and emergency services from seven counties were utterly overwhelmed by the blaze and the military had to be brought in to assist.32
Meanwhile, a report in the Sacramento Bee dated July 2, 2018, opined that California’s wildfire season had
started early, with two “major fires” already fought at huge expense and requiring evacuation of local residents. These two fires were estimated to have consumed 85,000 acres,33 which sounds an awful lot but in fact converts to just 344 square kilometers.
The previous year, 2017, was California’s most destructive wildfire season then on record, with a total of 1.25 million acres burned.34 The cost of dealing with the disaster, including fire suppression, insurance, and recovery expenditures, was estimated at US$180 billion.35 Yet 1.38 million acres converts to just 5,585 square kilometers—an insignificant fraction (around 0.05 percent—that is, a twentieth of 1 percent) of the 10 million square kilometers destroyed in the Younger Dryas wildfires.
It seems, therefore, that the United States and Britain, two of the world’s wealthiest, most technologically advanced, and most powerful countries, face great difficulties in confronting what are, in the grand scheme of things, relatively minor wildfires. Imagine, then, the consequences for all living things of the great inferno that consumed 9 percent of the earth’s biomass around 12,800 years ago and that left an indelible record of its climatic and atmospheric impact in lake sediments and Arctic ice.
IMPACT WINTER
NEWS FOOTAGE OF THE US AND UK summer wildfires shows smoke everywhere. Close up it seems foggy or misty. In the longer view there’s an obvious gloom, a darkening of the skies, where the pall obscures incoming sunlight. It’s a local effect, of course. Fifty miles away the air is clear and the skies are blue.
The 2018 Journal of Geology study reports that matters would have been very different at the onset of the Younger Dryas, when the smoke from 10 million square kilometers of burning biomass would have enshrouded the entire earth, creating what Wendy Wolbach and her coauthors describe as an “impact winter.”36
This is a concept derived directly from research in the early 1980s revealing previously unexpected consequences of a nuclear war in the form of a “nuclear winter.” The findings of that research were first put before the public in October 1983 in an article by esteemed astrophysicist Carl Sagan under the headline “In a Nuclear Exchange, More Than a Billion People Would Instantly Be Killed, But the Long-Term Consequences Could Be Much Worse.”
Appearing in a mass-circulation magazine, Sagan’s article showed that the immense quantities of dust and smoke arising from multiple nuclear explosions, and from the wildfires they sparked off, would significantly reduce the amount of sunlight reaching the surface of the earth, causing a steep and sustained fall in global temperatures, widespread failure of crops, and devastating famines. Nor would a full-scale war between superpowers be required to bring on the terrible, and potentially terminal, consequences of a nuclear winter. Even a regional nuclear conflict could do it.37 “We have placed our civilization and our species in jeopardy,” Sagan concluded.38
In the case of the Younger Dryas, the jeopardy that humanity faced was not from nuclear missiles but from the incoming fragments of a disintegrating giant comet, traveling at tens of kilometers per second, with the larger fragments as deadly as hundreds of nuclear warheads. Indeed, it is estimated that the total explosive power of the comet fragments that struck the earth in repeated episodes over a period of 21 years some 12,800 years ago would have been of the order of 10 million megatons39—1,000 times greater than all the nuclear devices stockpiled in the world today.40
The Younger Dryas is already recognized as an epoch of extreme, anomalous cold that lasted for approximately 1,200 years, setting in fast and suddenly around 12,800 years ago and ending, equally suddenly, around 11,600 years ago. The Journal of Geology study greatly enriches this picture with compelling new evidence that the onset of this 1,200-year “deep-freeze” was marked by a brief period of extremely intense and large-scale wildfires triggered by “the radiant and thermal energy from multiple explosions” as fragments from the comet swarm pelted the earth:
This widespread biomass-burning generated large amounts of long-lived, persistent AC/soot that blocked nearly all sunlight, rapidly triggering an impact winter that transitioned into the YD cool episode.41 …
The negative effects of AC/soot might have persisted for 6 wk or more at the YD onset, blocking all sunlight and causing rapid cooling. Reduced insolation is also expected from the injection of comet dust to the upper atmosphere. If so, the lack of sunlight would have had widespread and catastrophic biotic effects, including insufficient light for plant photosynthesis and growth. At the same time, North Atlantic deep-water formation ceased, thus throttling the so-called ocean conveyor and triggering a sustained decrease in near-global temperatures.42
THE MAMMOTH IN THE ROOM
IT HAS LONG BEEN UNDERSTOOD that an interruption of the warm Atlantic current known as the Gulf Stream correlates with YD cooling, and it is generally agreed that
a great gush of cold freshwater derived from the melting Laurentide ice sheet … swept across the surface of the North Atlantic. It prevented warm, salty water from the southern ocean flowing deep below the surface (the Gulf Stream) from rising to the surface. The normal overturning of the ocean water stopped. As a consequence the atmosphere over the ocean, which would normally have been warmed, remained cold and so, in consequence, did the air over Europe and North America.43
It’s revealing, looking back through the scientific literature, to see how long explanations of this sort were simply taken for granted. That there had been a cold-water flood was not in doubt, so the detective work that at first interested scientists most was WHERE all the water had come from.
The reader will recall that the North American ice cap had two distinct segments consisting of two separate ice sheets, the Cordilleran in the west and the Laurentide in the east, which were often joined, but which in the later stages of the Ice Age were separated by the famous “ice-free corridor” that for a long while was erroneously believed to have been the sole route for human migration into the Americas. Along the southern margins of these ice sheets, enormous glacial lakes formed and were prone to flooding—most famously glacial lake Missoula in the west and glacial lake Agassiz in the east. Floodwaters out of Lake Missoula would have had no access to the Atlantic Ocean (they would have been routed into the Pacific). Lake Agassiz was therefore thought to be the most likely source, and a study published in Geology in January 2018 confirms that its floodwaters “could have been routed eastward to the North Atlantic at the Younger Dryas onset and caused the canonical abrupt climate shift.”44
After Geology, “Opening of Glacial Lake Agassiz’s Eastern Outlets by the Start of the Younger Dryas Cold Period,” January 4, 2018.
So we know that a cold-water flood poured into the Atlantic ocean around 12,800 years ago on a scale sufficient to stop the Gulf Stream in its tracks; we know that glacial lake Agassiz has been implicated in it; and we know that this “great gush of cold freshwater” has been connected to the plunge in global temperature—the “deep freeze”—that defines the Younger Dryas cold event.
The issue that most of the scientists are skirting, however—the mammoth in the room—is why such a flood would have occurred at the onset of the Younger Dryas “deep freeze” around 12,800 years ago rather than, say, 800 or 1,000 years earlier at the height of the warm phase—known as the Bølling—Allerød interstadial—that immediately preceded the Younger Dryas.45 Intuitively one feels the meltwater floods should have been at their peak during the warming phase. Why, therefore, in this case only, do we see them at the onset of an extremely cold phase? I raised this problem in Magicians of the Gods in 2015,46 and it is raised again by Wolbach et al. in their 2018 paper, where they present evidence that deepens the mystery. “Unlike for typical warm-to-cold climate transitions,” they report, “global sea levels rose up to 2–4 m within a few decades or less at the YD onset, as recorded in coral reefs in the Atlantic and Pacific Oceans.”47
The point is understated, but this is a very big deal. Two to 4 meters of global sea-level rise within “a few decades or less” of the onset of the Younger Dryas
is an IMMENSE amount of water, a cataclysmic world flood by any standard.
What makes it all the more remarkable, however—and all the more puzzling—is the evidence from Wolbach’s study that in the exact same period the planet suffered a spectacular episode of biomass burning and an associated “impact winter” that “caused warm interglacial temperatures to abruptly fall to cold, near-glacial levels within less than a year, possibly in as little as 3 months.”48
Meanwhile, in the process of absorbing that sudden massive flood of icy water into the North Atlantic, the world ocean had reacted by shutting off the Gulf Stream, thus sustaining freezing temperatures in Europe and North America and setting in process the entire Younger Dryas cold episode.
What we are looking for, therefore, is an agent capable—simultaneously and almost instantaneously—of bringing about all of the following:
a global flood
wildfires across an area of 10 million km2
6 months of icy darkness followed by more than 1,000 years of glacially cold weather
a stratum of soil across more than 50 million km2 dated to the Younger Dryas Boundary (YDB) and infused with a cocktail of nanodiamonds, high-temperature iron-rich spherules, glassy silica-rich spherules, meltglass, platinum, iridium, osmium, and other exotic materials
a mass extinction of megafauna
Wolbach and her coauthors are forthright in their conclusion:
Multiple lines of ice-core evidence appear synchronous, and this synchroneity of multiple events makes the YD interval one of the most unusual climate episodes in the entire Quaternary record. … A cosmic impact is the only known event capable of simultaneously producing the collective evidence.49
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