Yes it does, if the criterion is the one in the column: a human surveying the surface. That’s why I asked my original question, what counts? What does surface mean? What does surveying mean? TriPolar said correctly that the pyramids might outlast more modern buildings, but what if they aren’t visible? Can’t play a game entirely without rules.
Anybody that mentions Calvinball will be gently but firmly shot at sunrise.*
*Not a threat. A quote made popular by Alexander Woollcott, although it isn’t original to him.
Unless ‘human surveying the surface’ means some guys just wandering about and hoping to stumble on something I think that includes all the types of surveying humans can and do use to survey the surface today…which includes ground penetrating radar and orbital surveying technology. Even if we just assume these are really dumb aliens simply wandering about hoping to find something the odds are in 10k years they will find plenty if they do more than touch down in one spot on the Earth and look around for an hour or two, plant a flag and fly home.
Now we’re getting into discussions about the hypothetical technology and motivations of hypothetical starfaring aliens, but…
Archeologists explore, dig, use ground-penetrating radar, etc. where they think they have a chance of finding something. Perhaps there’s a large visible relic (pyramids), perhaps there are smaller artifacts to be found, perhaps the local people have stories about something interesting in a cave, perhaps some type of record in another place suggests that there might be something to find.
So, aliens arrive at Man Disappearance +10,000 (or whatever). If they’re interested in whether there used to be intelligent life here, the easiest way is to cast around for visible signs of it. What if Mt Rushmore is dust and the pyramids are covered? Do they look harder? Do they search around likely spots such as river deltas and deep harbors, whose locations may have changed anyway since Man Disappearance? How much do these aliens care about finding evidence of prior civilization on a planet, enough to do a planetwide search with ground penetrating radar?
We can’t possibly know. I suggest that if the aliens think something like us, they probably have a look around to see if there are any civilized beings, or something like it. If in the course of that search they find nobody, AND see nothing worth noting, I suggest they move on with their lives.
Well, if they are even mildly curious (and humans would be) then they’d know pretty much instantly that something was here. All those satellite thingies if nothing else. Presumably having come here from somewhere else means they are already in space, so putting up their own satellites would be fairly straight forward and, presuming they have at least the tech we do then finding the outlines of former cities would be as easy for them as us finding extinct rivers or other large scale features. New York might not be there anymore, but all traces of it wouldn’t simply vanish…and there are thousands of human cities in every environment this planet has, including some that would be underwater or buried and in even better states of preservation. Now, whether aliens would have the same fascination humans do about ancient civilizations, ruins, etc, is certainly another question, but then why would they be here at all if they didn’t want to explore?
I answered that in post #22 when I said “Keep in mind that CO2 naturally fluctuates between 190 and 280 but humans have pushed it up to 400.” I’d be happy to explain a bit further.
This normal up-and-down rhythm has been going on for the last couple million years. Each up and down cycle lasts about 100,000 years. The pattern is that average global temperature very slowly drops to about 8 or 9° C while CO2 drops to 190 ppm and then the temperature slowly rises to 12 or 13° C while the CO2 rises to 280 ppm and then it repeats. On the way down (going into a glacial period), the average decrease is about 1 ppm CO2 per 1,000 years and on the way up (moving to an interglacial period) the average is 4 ppm CO2 per 1,000 years. Currently, we are in an interglacial period, which is why I said 280 is natural. That’s the level we’ve been at (give or take a few points) from 10,000 BC up until 1880 CE. Then we humans started pumping excess CO2 into the air and now it’s up to 400. If humans disappear today, it should drop naturally back down to 280 and then 10,000 years later we’d expect to see global average temperature dropping to about 12° C and CO2 dropping to about 270. That’s assuming that the normal rhythm which existed before humans reasserted itself after humans were gone.
Yes I know that CO2 was much higher in the way way distant past. For example, half a billion years ago, CO2 was ten times higher. But that really doesn’t help us estimate what would happen now in 2016 if humans disappeared. To answer that question, we should be looking at the normal up-and-down cycle of glaciation which I described above.
That’s not my “larger point”. I’m not claiming that all the links in this line of reasoning are true. I just laid them out for Quartz, as they were presented over the course of this discussion. TriPolar, said the pyramids in Egypt may outlast all of our modern artifices. I am not claiming that TriPolar is right or wrong about that. Exapno Mapcase said sands would cover the pyramids, given an expansion of the Sahara from warming. I have no opinion on whether Exapno Mapcase is right or wrong on that claim. Musicat asked if global warming would continue with no human activities to fuel it, to which I replied Yes, AGW would continue for a few decades. That last part is my claim.
I said we’re discussing the question of whether continued AGW might or might not cause the Sahara to continue expanding, which might or might not cause the pyramids to be covered in sand, which might or might not cause them to be destroyed/preserved. There’s a chain of discussions, one item leading to another. If all of them are true then we might see the end result. Emphasis on the words if and might.
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I answered that in post #22 when I said “Keep in mind that CO2 naturally fluctuates between 190 and 280 but humans have pushed it up to 400.” I’d be happy to explain a bit further.
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Feel free, though this isn’t a thread about AGW really. However, you seem to be saying that the ‘natural’ levels of CO2 are between 190-280…except for all the times it wasn’t. I’m not disputing that humans are adding CO2 to the environment, not disputing that this is causing a shift in global climate or any of that, I’m simply trying to figure out where you are getting that the earth has some sort of ‘natural’ level of CO2.
It was much higher later on as well. Assuming the models used in the chart in this article are correct, looks to me as if it’s fluctuated wildly over the last half a billion years, and has had many instances as high or higher than today, so not sure I’m seeing what’s ‘natural’ here (I’m not saying it’s been higher FASTER, btw…I fully concede that THIS time it’s gone up much faster much quicker and that’s directly due to humans and our evil ways). No doubt humans are pushing it up today, and you are right, that’s not going to shift instantly if humans disappeared tomorrow, but CO2 doesn’t seem, to me, to have a ‘natural’ level, but instead fluctuated depending on a ton of factors, and even if humans weren’t here it would be doing so…just not as extreme is as short a time.
At any rate, I don’t see how an expanding Sahara (or a shrinking one for that matter) would doom the pyramids from the perspective of our theoretical alien archaeologists view, which is more relevant to the actual discussion of this thread. I’m not sure any likely geological process in that region would erase all traces of the things in 10k years, regardless, though of course this supposes our alien archaeologists are interested in doing more than a flags and foot prints survey of the Earth. A million years? Yeah, I’d buy that this might mask the Giza complex sufficiently to fool our aliens, but 10k? :dubious: I’m very skeptical of the Life Without Humans and Population Zero shows claims about human cities pretty much vanishing on such short (geologically speaking) time frames across the entire planet. To me, they are taking a couple of pieces of data (such as abandoned cities in Russia or elsewhere), they extrapolating what would happen in a few cases (such as New York), them making sweeping claims from there. It’s certainly entertaining, and I enjoyed the shows as I said, but I don’t think their conclusions are worth more than those drawn by the big haired Ancient Aliens guy…and they are pretty much drawn for the same reasons. It gets good ratings. YMMV, and I know you are wanting to talk about AGW again, so I’ll leave it there. Was a disappointing article to me, and part of a disappointing trend lately…either the new ‘Cecil’ has a different view point, or the old one has had a fairly radical change in perspective. Either way, I’m not enjoying the articles as I used too.
I don’t get your dubiousness. We know that the majority of structures we call pyramids, but including auxiliary buildings, have been buried by sand and have done do in much less than 10,000 years. The remaining exposed structures are the exceptions. We are just beginning to find what’s buried there using viewers much more sophisticated than the eyeball.
Of all the things in this thread to doubt, that Saharan sands bury even large piles of stone strikes me as among the oddest.
Some confusion going on then. I don’t doubt they could be buried. I doubt that, being buried that makes them undetectable or unobservant to a theoretical space going alien species checking us out in 10k years. Same with our cities. I don’t dispute that many if not most of the buildings would rot away in that time frame…I doubt that this means they wouldn’t leave behind evidence that could be detectable in 10k years to archaeologists. As we see evidence of fossil rivers today we’d see similar evidence of humans. As we find mammoth carcasses or even soft tissues on dinosaurs we’d find many examples of human activities. As we find dinosaur foot prints, etc etc. It gets back to your earlier question about what a surface survey consists of…I say it consists of what an interstellar alien species would likely have at their disposal to observe interesting planets they decided to investigate, which would be at least as good as what we have today…and we’d find it if it was there. Just like we find lost cities, pyramids, temples and other things of earlier civilizations.
CO2 going up and down between 280 and 190 is “natural” in the sense that it’s the stable predictable pattern which has dominated Earth’s environment for over 2 million years–ten times longer than our species has existed. It’s the backdrop against which Homo Sapiens evolved, and it’s the recent pattern which would reassert itself if we disappeared. Those wild fluctuations which happened hundreds of millions of years ago aren’t relevant to a discussion about what the world may look like a mere 10,000 years from now.
Would satellites still be in orbit 10,000 years from now? Don’t all their orbits decay?
There’s the stuff we left on the moon, that will still be around, although you’d really have to be looking.
As for why aliens would come–well, maybe they’d be looking for intelligent humanoids lifeforms to eat or enslave, and a cursory glance revealing none, they’d move on. Or they were hoping the Earth would be hotter and suitable for colonization, but it isn’t so they leave right away. Or they’re only interested in mineral resources. Or vanished civilizations are so common that it’s not worth searching out another one. I can imagine a lot of reasons that don’t include “scan a whole planet for buried signs of past civilizations.”
There’s no reason to think the planet won’t be covered with lush life. New species may be emerging, the niches left by our absence might be filled in interesting ways, but the planet should clearly be one that supports life. Unless planets like this turn out to be very common the aliens will spend a little more time on this one than the various desolate rocks and iceballs out there.
The problem there is that all the readily sources of energy like petroleum, coal, and natural gas has been used. They will have to spend alot of time drilling for new sources. Even all the easily available iron ore has aleady been mined.
I agree. Class M planets would be valuable real estate for carbon-based life forms.
And even if they didn’t want to settle here, they might find Earth to be a perfect feeding ground for Gargons. Anyone who says otherwise will be sentenced to TORCHA!
In a million years, ice ages and earthquakes may render everything that man has created to be erased from the face of the Earth. A visiting alien or a new sentient life form may never know that we once existed and dominated this planet.
Ironically, the equipment and junk left on the moon will remain around. You won’t find evidence that humans once existed and dominated the Earth on Earth, but you will find it on the moon.
:dubious: There are foot prints created by dinosaurs walking through mud that are clearly visible today from 64 million years ago (and older), so I’m pretty skeptical that ‘everything that man has created to be erased from the face of the Earth’ is going to happen in a million years. Granted, it might take some digging or more intense searching…or not, since some of those foot prints were just found by folks tromping about.
I think some of the stuff in orbit around the Earth (especially some of the stuff pushed into graveyard high orbits) will still be orbiting a million years from now as well, btw, so it’s not just junk on the moon, though much of it might just be debris by a million years. But it would be pretty odd debris that even a cursory examination by our theoretical aliens would indicate it wasn’t asteroid or cometary in origin.
I wonder about our modern “middens”. We’ve been able to find discarded items from human activity thousands of years old. However, those items are all eventually biodegradable, and absent contact with the elements, they have lasted a long while. Our modern trash is filled with plastic, glass, and other materials that, it would seem, would last even longer if not exposed to the elements.
Perhaps in a few million years one of our landfills will be eroded by a nearby river and expose a sediment layer filled with plastic, bottles, diapers, styrofoam, and tupperware. It makes interesting conjecture as to what an intelligent life form would interpret from our trash.
They will also find the remains of earth satellites on Mars or else just floating around the solar system. Remember Voyager became V’ger in that first Star Trek movie?