Upon re-reading the article, I did not remember the length of the “nuclear winter” phase correctly. In fact, instead of years, it may have only lasted months. The reason? The fires, in addition to the vaporization of a huge amount of limestone, released such a volume of greenhouse gases into the atomosphere that the planet experienced their global warming effects soon after the dust began to settle.
Also, interestingly enough, the northern parts of North America and Asia perhaps weren’t such a bad place to be after the impact, while one was far worse off in India (such as it was at the time), almost antipodal to the impact site, due to the trajectory of the debris that came raining back down on the Earth. Africa and Australia also were hit pretty severely.
Anywhere was probably horribly rough after the fires, though, as photosynthesis was essentially shut down for months during the “nuclear winter” period.
Well, I can’t say that either is specifically wrong, only that in this one comprehensive study of survival patterns, the hypothesis that global wildfires and associated effects would act as the proximate killer does not mesh with the survival patterns in the Hell Creek area. It is entirely likely that different areas would have suffered varying effects from the assorted events that were taking place at the end of the Cretaceous, including different areas suffering different effects from the impact event itself. But I would think that the relative proximity of South Dakota to the impact site* should have rendered it somewhat more susceptible to whatever killing effects the asteroid impact did have, yet there was still a 49% survival rate among species in that environment. I’m not saying that the global fires didn’t happen, or that they didn’t kill off some species in themselves, just that there is no discernable reason why some species might have survived not just the fires, but the whole of the impact event itself.
And even if it were a case of “special circumstances”, we really aren’t any better off (in terms of being able to predict survivability in subsequent impacts) since we have no idea what those circumstances might have been, which, again, doesn’t help determine if we humans might benefit from those or similar circumstances.
- By my very rough estimates, South Dakota lies approximately 2,700 km from the Yucatan Peninsula. Based on data from this site, the fireball itself would almost immediately ignite everything within about 1,800 km. The blast wave would extend over 4,000km from the point of impact, and that’s not even counting the subsequent “global firestorm”. I would think that being a “mere” 2,700km from such an impact, with little more than flat ground between Point A and Point B, would have resulted in significantly different survival patterns (most significantly, fewer survivors in the first place!).
These are all very good points, but there’s one thing that I perhaps am not getting, and I don’t want to misinterpret: You seem to be arguing, based on the fossil record from Hell Creek, that the impact couldn’t have been as disasterous as the 100 teraton figure being quoted. Is that a correct reading of your statements?
No, not really. What I am saying is that there is more to survival patterns of known asteroid impacts than meets the eye. We simply aren’t knowledgeable enough about, say, dinosaurian physiology to know which, if any, of the various environmental effects that would result from a massive asteroid impact would have acted as the actual “killer”. We don’t know enough to say why all (non-avian) dinosaurs died out, but only some sharks (which suffered localized, rather than global, extinctions). Nor why lizards seemed to take it in the proverbial teeth, but crocodilians weathered the times with minimal losses. Nor do we know why all of the amphibian species in the Hell Creek Formation survived the event(s), yet today amphibians are considered key indicators of an ecosystem’s health; if the ecosystem begins to fail, they are often among the first to suffer (witness the attention being paid to various Amazonian frogs, for example).
The Chicxulub impact was undoubtedly disastrous. But the fossil record seems to indicate that as disastrous as our current models indicate such an impact should be, a number a species would (and did) still survive the impact, and that the impact hypothesis alone does not account for the wide variety of species which did go extinct at the end of the Cretaceous. Granted, the asteroid did almost no one any good at the time, but, again, there seems to be more at work here than is readily apparent.
And, because of our uncertainty with respect to what should happen and which species should be hit hardest, we can’t really say what our own fate would be in a similar situation. It would undoubtedly suck harder than anything has ever sucked for humanity before, but we really don’t know enough to say it would spell the end of our species altogether (or even that it wouldn’t).
Gotcha. Thanks! Interesting discussion…nothing seems to spark my imagination like things that, y’know, blow up. 
Here’s a good website on the subject. One of the authors of the site is also an author of the SciAm article I linked, and contains a nice summary of the info. in the article, plus some other cool stuff on the KT Boundary.
http://www.lpl.arizona.edu/SIC/impact_cratering/Chicxulub/Chicx_title.html#start
A crather 30 million km wide and 10 million im deep? That’s one heck of a crater…
The actual level of destruction that resulted from the asteroid that “killed the dinosaurs” has a vast range depending on who you talk to. And this is a vast range coming from many trained scientists who are experts in geology and other related fields.
The after effects of the strike are also widely varied depending on who you ask.
Some people are doomsayers while others play down the asteroid as the dinosaur killer.
There is actually a large number of professionals who think the dinosaurs simply died out because of climate change that their reptilian bodies couldn’t adjust to.
Now of course many modern species were around back then. The cockroach for example is estimated to be 250+ million years old, but cockroaches have been reported to survive post-nuclear attack radiation levels fairly unharmed (anectdotally.)
But turtle and crocodilians, as mentioned were alive and fairly the same as they are now back even before most of the large land dinosaurs began to populate the planet.
However the Chicxulub incident is widely accepted as having either a significant or almost complete influence on the late Cretaceous mass-extinction.
I tend to think the strike had a lot to do with a lot of the dinosaurs dying off, but I think there were other factors at play as well. Supposedly the dinosaur population hadn’t been doing too well for a while prior to the strike, either.
Because most paleontoligists note that the dinosaurs really went extinct over a period of 10 million years.
Which is somewhat contradictory to the Alvarez theory because even a 10km asteroid wouldn’t cause mass global effects like blocked sunlight for 10 million years running.
Other than that one fact most of the theory is widely accepted, but that doesn’t necessarily mean that effects as dramatic as described in this thread necessarily happened. Dinosaurs as reptiles were almost certainly cold blooded (although I’ve seen it postulated maybe they weren’t!) so you wouldn’t need the blacking out of the sun for millenia to wipe them out.
Also considering the size of many dinosaurs, you wouldn’t need global extinction to wipe them out, many of them were very specialized and a fairly moderate reduction in flora or fauna would probably have led them to extinction fairly quickly.
Anyways, whatever DID happen when the Chicxulub asteroid (or comet) impacted earth, if something of similar proportion happened tomorrow I believe the human race would survive just fine?
Why? Our mammalian ancestors did it 65 million years ago, which is why mammals are the “dominant species” today. If ancestors to modern day rodents could do it, I think we could too.
Also I’m going to say that more than likely the sun wasn’t blocked out 100% or close to 100%. It was probably significantly blocked, but since even the worst of the doomsayers only speculate 50% of the world’s animal species went extinct it’s unlikely the sun was completely blocked out or the number would have been nearly total as virtually all living things on this planet would die and we’d see Antarctic level cold globally if that was the case.
A complete blockage of the sun would probably only leave microscopic species alive and that wasn’t the case.
The only thing good about our technology is mass production. Everything else is practically useless. eBay, excel files, and SAP servers are not going to help your quest through the dusty skys. Well, maybe GPS…
One of the early casualties would be the idea that humans are above evolutionary effects.
No, thanks to our friend the Square/Cube Law, the crater would only have linear dimensions equalling the cube root of ten million, or 216 times as wide. And gravity would prevent the crater from being much more than about 10 kilometers deep. Still, we’re talking about a pretty big hole.