It was apparently much worse than we thought:
As Kennett noted in a recent article in The Current (a university press maintained by UCSB), the crater would have led to widespread destruction, characterized by biomass burning, megafaunal extinctions and global cooling. “It’s much more extreme than I ever thought when I started this work,” he said. “The more work that has been done, the more extreme it seems.”
The discovery was made possible by a Chilean group of scientists who were studying sediment layers at the well-know Quaternary paleontological and archaeological site, known as Pilauco Bajo. Years ago, these scientists recognized changes in the sediment record that were associated with the YDB impact event.These included a “black mat” layer that coincides with the disappearance of South American megafauna fossils and human artifacts dated to the Pleistocene (12,800 years ago), indicating a severe shift in the climate. This was a major find since the vast majority of evidence for the YDB Impact has been found in the northern hemisphere.
Imagine that happening today. And here we’re obsessing over two degrees Celsius.
Better get moving on that vital SLS, so we can protect ourselves. #NotReally
I’ve long wondered if the Younger Dryas impact theory is based on a flawed assumption: that there was a significant impact.
The reason for my skepticism is the contrary evidence cited in other studies: the near- absence of carbon spherules associated with ejecta – too few found for an impact event large enough to do this.
So, I wonder, what if both sides are right – there was no significant impact, but, Youger Dryas was caused by an asteroid?
What I’m thinking is a very, very shallow angle of incidence with the atmosphere, resulting in airburst. Especially if the asteroid (or perhaps a metal-rich comet, though I’m skeptical) fragmented (such as Shoemaker Levy did prior to Jupiter impact) resulting in multiple massive airbursts (Tunguska, or the Cheblinsk event, though on massive scale). That would certainly cause fires over vast regions, while also putting megatons particulate asteroid debris in the upper atmosphere.
But what you would not have is a series of craters of any significant size.
Plausible?
I do think that, given the evidence for bombardment frequency that’s coming out lately (such as the hundreds-of-kilotons event over the Bering Sea a few years ago, just announced) that asteroid and cometary events are an even bigger risk than thought. I also do not think significant attention or defense research will be done, because there’s no motive; you can’t tax ’em, and it’s not a means to impose more rules on people.
I don’t know about the start, but I’ve seen some pretty convincing arguments that the Younger Dryas was ended by a comet impact in the middle of the North American ice sheet. That event would account for the prevalence of flood stories worldwide.
I attended a lecture by the world’s hottest astrophysicist, Dr. Amy Mainzer, whose main topic was NEO asteroids. She lost credibility with me when she noted that the Chicxulub impact was associated with a global layer of elemental carbon. Her surmise was that all of the surface plant life had been set afire, and burned entirely, causing a huge amount of CO2 being released, and ultimately resulting in lethal global warming. So, in her mind, it was global warming that did in the dinosaurs. I didn’t have the heart to point out that burning all of the surface vegetation meant cutting off the food chain at its lowest level, producing immediate starvation of all higher species.
I’d still attend any lecture she gave, and listen to her sweet little lies. Siiiggghhhhh…..
There is some growing push back against the Chicxulub impact entirely explaining the extinctions, as coincident with it were truly massive lava flows in India, the Deccan Traps, that went on and on.
Fascinating article in The Atlantic titled “The Nastiest Feud in Science”.
In addition to the Deccan Traps, I’ve heard that the Siberian Traps are associated with the Permian extinction.
But what causes these massive lava outflows in places not known for active volcanoes, that go on and on? I would think that an impact large enough to punch through the crust and expose the mantle would do the trick. And the lava outflow might obscure the original crater.
I’m not a geologist, so it’s just speculation on my part.
I read an interview she did a while ago with a reporter that went on an expedition with her, his article was memorable for the vast amount of abuse Keller directed at her critics, I don’t think she’s the innocent victim she imagines herself to be.
I don’t care how anyone voted and that she isn’t an astrophysicist; Amy Shira Teitel is way hotter.
Any parent can tell you when you give a little kid a hammer, his world fills up with “nails. Academics are like that.” My father was a geologist and while I didn’t follow in his footsteps, I learned a lot from him and gave maintained an interest in things geological. It sometimes seems to me that major extinction events take a one-two punch. In the case of the End-Paleozoic (Permian-Triassic) and End-Mesozoic (Cretaceous-Paleogene) Events, it was a combination of flood-basalt eruptions and one or more large meteor impacts. The Earth is like a loaded single-action revolver, one event cocks the gun, the other pulls the trigger. We also know major carbon sequestration events can cause mass extinctions, such as multi-continents tectonic mergers. There’s even one event suspected to have been caused by a long-lasting aquatic plant bloom on a stagnant, land-locked Arctic Ocean. Over the course of a few hundred thousand years (perhaps less) the plants extarcted carbon from the air and sank to the seafloor when they died, dropping the CO2 content of the air from 900ppm to 440ppm, triggering the icehouse climate that persists to this day. At least, that’s the theory…