You at least tried to explain the scenario. However, I don't believe that the volume of dirt and rock expelled by the impact is enough to engulf the entire planet.
It could cause heavy local damage. But it can't cause global extinction, unless the volume of dirt is the size of a continent.
> You at least tried to explain the scenario. However, I don't believe that the volume of dirt and rock expelled by the impact is enough to engulf the entire planet.
Have you done the math, or is this based on a gut feeling?
Because the people who have done the math disagree with you. Some of the ejecta would be thrown well out of the earth's gravitational pull, the other would end up various suborbital trajectories, coming down over the next day or so across the entire surface of the earth. Their re-entry heating will be enough to turn the entire sky incandescent, and the radiative heating will essentially barbecue the entire surface of the earth. Only swimming, burrowing or cave-dwelling animals would survive.
Also it depends on whose gut the feeling belongs to. To mine it doesn't sound so preposterous that an object falling from space at a huge velocities can cause ejecta which also flies up at huge velocities. Surely doing the math is the key for a proper answer but having a gut feeling can be a useful first order guide on a subject, as long as one remains open to further argumentation to further refine one's intuition.
As I understand, the plume of dirt then envelopes the planet with a blanket of dust, causing dramatic temperature reduction by blocking sunlight. Animals immediately dependent on food from the sun die very quickly, as the blanket of dust takes a very long time to dissipate.
There is also the possibility of increased volcanic activity due to disruption of the crust, depending on where it occurs and how large the impacting object is. That can exacerbate and prolong the blanketing of the earth, and introduce severe air quality issues as well.
I’m sure there are other challenges to life as well. It sounds like misery for decades.
I appreciate that you remain willing to engage in the subject. I’m not a physicist myself but I’ve been exposed to physical science enough to be wary of statements like this:
> It could cause heavy local damage. But it can't cause global extinction, unless the volume of dirt is the size of a continent.
If someone is going to make this claim academically, they will have calculated a whole bunch of things -- with perhaps some assumptions to numbers like mass, volume, velocity of the asteroid so they can play around with them as variables.
I will admit I have not dug deeper into this to find the numbers myself and do the relevant calculations. That is, in part, why I choose to be explicit about “theorized”. It’s what might have happened, given what we know, but it’s hard to be sure of what happened unless one studies the relevant ideas.
Assuming all energy went to the air, and you live in a nice place where the temperature is already 20°C(70°F) then the temperature increase to 40°C (100°F). That's bad, but you probably have time to jump into a lake if it's nearby (otherwise you are toasted).
This is mush less than an oven temperature like in the GP comment.
Almost none of the energy goes into the air. Air is barely heated by radiation, because it is transparent.
What happens is that the re-entry heating of the falling ejecta produces radiative heating, which directly heats the surface of the earth. And that gets cooked well past oven temperature.
The nice thing of energy conservation is that the details doesn't mater. So the energy of the radiative heating is less than the original energy of the meteorite that I estimated in 9.5E22 J. I guess it's much less, but it's a good upper bound.
The surface of the Earth is 5.1E14 m2, so it's 1.8E8 J/m2. I don't expect the fireworks to be synchronized so let's assume that they fall in an hour. That gets 50,000 W/m^2 For comparison, sunlight is 1,300 W/m^2 so it's almost like 40x sunlight. This bad, very bad.
I don't expect a 100% conversion of meteorite energy to fallout energy, but it's more dangerous that my initial calculation.
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I'm confused because the weight of the atmosphere is like the weight of 10m of water. So heating all the atmosphere is like heating a 10m layer of water. But actually water has a much bigger heat capacity, so the final temperature would be smaller. And dirt has an intermediate value. Also the radiation would not heat 10m of water or dirt, perhaps only the first meter.
So I expected that if my first calculation got a not dangerous temperature increase, I'd get in this second calculation a not dangerous result. So I guess I made a mistake in at least one of the calculations or my hand waving has a mistake.
I assume we have models for these dynamics. Anecdotally we recently had a couple wildfires in Canada that blanked a significant % of the US with smoke. You could drive through multiple states where the sun was partially blotted out.
The K-Pg impactor was larger than Mount Everest and the energy released in the impact was approximately 1000 times larger than the total combined nuclear arsenals of all countries.
You at least tried to explain the scenario. However, I don't believe that the volume of dirt and rock expelled by the impact is enough to engulf the entire planet.
It could cause heavy local damage. But it can't cause global extinction, unless the volume of dirt is the size of a continent.