What-If 0053: "Drain the Oceans"

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What-If 0053: "Drain the Oceans"

Postby higgs-boson » Tue Jul 09, 2013 2:56 pm UTC

What-If 0053: "Drain the Oceans":



How quickly would the ocean's drain if a circular portal 10 meters in radius leading into space was created at the bottom of Challenger Deep, the deepest spot in the ocean? How would the Earth change as the water is being drained?

–Ted M.



(-50m)"And after 2000 years of trying to hold back the sea, the Netherlands are finally high and dry. No longer living with the constant threat of a cataclysmic flood, they're free to turn their energies toward outward expansion. They immediately spread out and claim the newly-exposed land."

... much to the dismay of the German neighbours which hoped that due to climate change they'll soon never get troubled by the Dutch pros in the Soccer Championships anymore.

(-1000m) "New Zealand grows dramatically. The Arctic Ocean is cut off and its the water level stops falling. The Netherlands cross the new land bridge into North America."

Um. Wait.

(-5000m)

Wait! I said!
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Re: What-If 0053: "Drain the Oceans"

Postby jgh » Tue Jul 09, 2013 3:16 pm UTC

Cool! You'd be able to walk from old Zealand to New Zealand!

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Re: What-If 0053: "Drain the Oceans"

Postby peewee_RotA » Tue Jul 09, 2013 3:22 pm UTC

I prefer to call south netherlands the nether regions.
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Re: What-If 0053: "Drain the Oceans"

Postby 9hili9 » Tue Jul 09, 2013 3:25 pm UTC

It would actually take hundreds of thousands of years for the ocean to drain.


Umm ... what am I missing? A rate of 1cm/day should only take 275 years to drop 1km. Should it be a thousand years (hundreds of thousands of days)? Should I rush home and fill the bathtub, this instant?

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Re: What-If 0053: "Drain the Oceans"

Postby Vo2max » Tue Jul 09, 2013 3:30 pm UTC

9hili9 wrote:
It would actually take hundreds of thousands of years for the ocean to drain.


Umm ... what am I missing? A rate of 1cm/day should only take 275 years to drop 1km. Should it be a thousand years (hundreds of thousands of days)? Should I rush home and fill the bathtub, this instant?


The rate will get slower as the level falls and the pressure drops.

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Re: What-If 0053: "Drain the Oceans"

Postby rmsgrey » Tue Jul 09, 2013 3:36 pm UTC

9hili9 wrote:
It would actually take hundreds of thousands of years for the ocean to drain.


Umm ... what am I missing? A rate of 1cm/day should only take 275 years to drop 1km. Should it be a thousand years (hundreds of thousands of days)? Should I rush home and fill the bathtub, this instant?


It says less than 1cm/day for the initial rate - depending how much less, it could be hundreds of thousands of years. More significantly, the drainage rate will itself slow as the oceans empty and the pressure drops. Ultimately, you reach the point where, rather than water flowing from the remaining oceans to the drain, you have water evaporating and falling as rain in the drain's catchment area as the only source of outflow (well, that and whatever happens to the air over the hole, which is a whole other problem)

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Re: What-If 0053: "Drain the Oceans"

Postby Barstro » Tue Jul 09, 2013 3:37 pm UTC

When you started, the water level would drop by less than a centimeter per day.


We can easily double that rate if we can convince Thor to drink from Útgarða-Loki's horn a few more times.

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Re: What-If 0053: "Drain the Oceans"

Postby groszdani » Tue Jul 09, 2013 3:42 pm UTC

1. Why does the first map say "ACTUAL SIZE"?
2. Why does this what-if page make Firefox and X.org very slow and use a lot of memory?
3. Is there any connection between the two things?

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Re: What-If 0053: "Drain the Oceans"

Postby Klear » Tue Jul 09, 2013 3:58 pm UTC

So... what would happen on Mars? Would it be able to keep all the water? How much of its surface would get flooded? I'm guessing Olympus Mons would still stick out of the ocean, but Mars is a lot smaller than Earth...

Randall places the portal directly above Curiosity, though he doesn't specify how high... I suppose if it was low enough, the portal would eventually get underwater, further slowing the flow and maybe even stopping it before Earth is fully drained...

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Re: What-If 0053: "Drain the Oceans"

Postby cellocgw » Tue Jul 09, 2013 4:03 pm UTC

Klear wrote:So... what would happen on Mars? Would it be able to keep all the water? How much of its surface would get flooded? I'm guessing Olympus Mons would still stick out of the ocean, but Mars is a lot smaller than Earth...

Randall places the portal directly above Curiosity, though he doesn't specify how high... I suppose if it was low enough, the portal would eventually get underwater, further slowing the flow and maybe even stopping it before Earth is fully drained...


I don't think the portal's altitude is a factor. So long as the water is free to flow over the surface of Mars (as opposed to, say, some local crater whose lip is higher than the portal), there's no back-pressure effect. Try it at home, tho' unless you're rich enough to get a portal from 1-800-PORTALS, use a garden hose and a couple of trash cans or something.
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Re: What-If 0053: "Drain the Oceans"

Postby Klear » Tue Jul 09, 2013 4:12 pm UTC

cellocgw wrote:
Klear wrote:So... what would happen on Mars? Would it be able to keep all the water? How much of its surface would get flooded? I'm guessing Olympus Mons would still stick out of the ocean, but Mars is a lot smaller than Earth...

Randall places the portal directly above Curiosity, though he doesn't specify how high... I suppose if it was low enough, the portal would eventually get underwater, further slowing the flow and maybe even stopping it before Earth is fully drained...


I don't think the portal's altitude is a factor. So long as the water is free to flow over the surface of Mars (as opposed to, say, some local crater whose lip is higher than the portal), there's no back-pressure effect. Try it at home, tho' unless you're rich enough to get a portal from 1-800-PORTALS, use a garden hose and a couple of trash cans or something.


Mars is smaller than Earth, so as Earth gets drained, Mars will be filled with water... How soon that happens depends on the current elevation of Curiosity, but it should happen sooner or later.

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Re: What-If 0053: "Drain the Oceans"

Postby Vroomfundel » Tue Jul 09, 2013 4:14 pm UTC

rmsgrey wrote:
9hili9 wrote:
It would actually take hundreds of thousands of years for the ocean to drain.


Umm ... what am I missing? A rate of 1cm/day should only take 275 years to drop 1km. Should it be a thousand years (hundreds of thousands of days)? Should I rush home and fill the bathtub, this instant?


It says less than 1cm/day for the initial rate - depending how much less, it could be hundreds of thousands of years. More significantly, the drainage rate will itself slow as the oceans empty and the pressure drops. Ultimately, you reach the point where, rather than water flowing from the remaining oceans to the drain, you have water evaporating and falling as rain in the drain's catchment area as the only source of outflow (well, that and whatever happens to the air over the hole, which is a whole other problem)


I'd say the rate of sea level drop will actually increase - the surface gets smaller, so you get 1cm drop with less volume.
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Re: What-If 0053: "Drain the Oceans"

Postby peewee_RotA » Tue Jul 09, 2013 4:16 pm UTC

rmsgrey wrote:
9hili9 wrote:
It would actually take hundreds of thousands of years for the ocean to drain.


Umm ... what am I missing? A rate of 1cm/day should only take 275 years to drop 1km. Should it be a thousand years (hundreds of thousands of days)? Should I rush home and fill the bathtub, this instant?


It says less than 1cm/day for the initial rate - depending how much less, it could be hundreds of thousands of years. More significantly, the drainage rate will itself slow as the oceans empty and the pressure drops. Ultimately, you reach the point where, rather than water flowing from the remaining oceans to the drain, you have water evaporating and falling as rain in the drain's catchment area as the only source of outflow (well, that and whatever happens to the air over the hole, which is a whole other problem)


As the surface drops, the size of the container changes as does the size of the surface. There'd be less pressure, but there'd be less water and less surface. The ocean is not straight walled beaker, the floor is sloped and mountainous. This is even more extreme in the examples shown where connected seas are no longer connected.

The smaller the surface, and the less water to flow, the more significant the loss of water will look.
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Re: What-If 0053: "Drain the Oceans"

Postby bouer » Tue Jul 09, 2013 4:19 pm UTC

I love doing this. I look at elevation charts and imagine how world history would have turned out differently if sea levels were slightly different.
I use this site merkel.zoneo.net/Topo/Applet/ a lot.

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Re: What-If 0053: "Drain the Oceans"

Postby richP » Tue Jul 09, 2013 4:24 pm UTC

More important than all of these calculations are the facts that:
* the sea is big.
* the sea can do whatever it wants.

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Re: What-If 0053: "Drain the Oceans"

Postby cellocgw » Tue Jul 09, 2013 4:47 pm UTC

richP wrote:More important than all of these calculations are the facts that:
* the sea is big.
* the sea can do whatever it wants.


You forgot the required footnotes :P
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Re: What-If 0053: "Drain the Oceans"

Postby rhomboidal » Tue Jul 09, 2013 4:52 pm UTC

I can't WAIT to play the updated version of Risk.

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Re: What-If 0053: "Drain the Oceans"

Postby peewee_RotA » Tue Jul 09, 2013 5:26 pm UTC

rhomboidal wrote:I can't WAIT to play the updated version of Risk.


WIN!
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Re: What-If 0053: "Drain the Oceans"

Postby speising » Tue Jul 09, 2013 6:30 pm UTC

for some reason, none of the images are displayed for me...

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Re: What-If 0053: "Drain the Oceans"

Postby trpmb6 » Tue Jul 09, 2013 6:33 pm UTC

I think there are a few issues that would also need to be investigated. Such as the impact of atmospheric pressure changes. My guess is most of the current cities would become uninhabitable once the sea levels hit 5km. Kind of hard to breath at 16,000 feet.

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Re: What-If 0053: "Drain the Oceans"

Postby NOTNOTJON » Tue Jul 09, 2013 6:50 pm UTC

HIJACK

Normally I enjoy a laugh at Randall's What-If's, but the end pictures on this rather fascinated me. I took the last pic (with Netherlands for fun) and applied some (very rough) plate drawings on it with some directional arrows. Here's the result:

Image
EDIT: Image wasn't embedding. here's the link:
http://imgur.com/qB9IOwY

What I think is worth thinking about is how it seems South America, Africa, Eurasia, and North America look similar, as though they all came from the same rift (maybe West of South America) and then were moved and stretched over time. I had never thought about this at all before (in fact there has been next to no rational thought on this yet on my part (lunch break at work)), but it might challenge the ol' Pangea model.

Thoughts?! (other than I might be a little bat-shit nuts)

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Re: What-If 0053: "Drain the Oceans"

Postby FrobozzWizard » Tue Jul 09, 2013 7:24 pm UTC

I think I should mention at this point that there are two kinds of people I can't stand: People who judge others by their nationalities, and the Dutch.

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Re: What-If 0053: "Drain the Oceans"

Postby Synthetica » Tue Jul 09, 2013 7:27 pm UTC

So we finally get to take back Nieuw Amsterdam, which some of you might call it "New York" or something, after all those centuries? When will this portal open? I'll be looking forward to it!

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Re: What-If 0053: "Drain the Oceans"

Postby Rombobjörn » Tue Jul 09, 2013 7:30 pm UTC

OK, now let's have a look at XKCD 681. Could someone please explain to me what would cause the water to flow from Earth to Mars? Venus or Jupiter look like much better places to put the portal.

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Re: What-If 0053: "Drain the Oceans"

Postby Copper Bezel » Tue Jul 09, 2013 7:35 pm UTC

Well, he's not accounting for gravity wells, else he wouldn't expound on the free-energy possibilities. It does remove the "finding a level" interpretation from earlier, but it's still self-consistent.

Klear wrote:So... what would happen on Mars? Would it be able to keep all the water? How much of its surface would get flooded? I'm guessing Olympus Mons would still stick out of the ocean, but Mars is a lot smaller than Earth...

I wonder how quickly it would cool? I mean, would it hit a point where it would begin to freeze at some distance from the portal? Ignoring that, going by this, Utopia Planitia would fill as an ocean first, then much of the northern hemisphere.

The bulk of the variation in elevation apparently falls into a range of ~17, stopping around 8km below and 9 km above the aeroid. And the aeroid can be treated as an average elevation, right? So halve the variation, and you'd need an ocean an average of 9 km deep to drown everything but the mountaintops.

Conveniently, the entire content of the Earth's oceans would make about a 9 km shell at that radius. = ) Of course, that includes the water left over in the seas at the end of the post.
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Re: What-If 0053: "Drain the Oceans"

Postby gmalivuk » Tue Jul 09, 2013 8:16 pm UTC

NOTNOTJON wrote:HIJACK

Normally I enjoy a laugh at Randall's What-If's, but the end pictures on this rather fascinated me. I took the last pic (with Netherlands for fun) and applied some (very rough) plate drawings on it with some directional arrows. Here's the result:

Image
EDIT: Image wasn't embedding. here's the link:
http://imgur.com/qB9IOwY

What I think is worth thinking about is how it seems South America, Africa, Eurasia, and North America look similar, as though they all came from the same rift (maybe West of South America) and then were moved and stretched over time. I had never thought about this at all before (in fact there has been next to no rational thought on this yet on my part (lunch break at work)), but it might challenge the ol' Pangea model.
What? How would that challenge anything? It's not as if the current model doesn't account for seabottom topology, after all, and that's all the new map really tells you about.
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Re: What-If 0053: "Drain the Oceans"

Postby higgs-boson » Tue Jul 09, 2013 8:22 pm UTC

groszdani wrote:1. Why does the first map say "ACTUAL SIZE"?
2. Why does this what-if page make Firefox and X.org very slow and use a lot of memory?
3. Is there any connection between the two things?


There are eleven images with a size of 5.926px × 3.726px bound to a relative width (100%) - maybe not all browsers / window manager handle this job with equal ease. In fact, at the time posting the thread's opener, for me the last image won't even load properly. Now all's fine.

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Re: What-If 0053: "Drain the Oceans"

Postby NOTNOTJON » Tue Jul 09, 2013 8:39 pm UTC

What? How would that challenge anything? It's not as if the current model doesn't account for seabottom topology, after all, and that's all the new map really tells you about.


It probably wouldn't -- I just never thought about it before. You see I'm working from a grade 7 or 8 [Pangaea] model in my head. It never occurred to me then and I haven't revisited the idea until now...

*goes off to brush away more cobwebs*

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Re: What-If 0053: "Drain the Oceans"

Postby mschmidt62 » Tue Jul 09, 2013 10:11 pm UTC

I'm guessing Randall didn't allow for rebound of the ocean crust upon removal of the weight of water. Such rebound would also result in the depression of continents. If you were a continent and your highest peak was now shorter, wouldn't you be depressed?

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Re: What-If 0053: "Drain the Oceans"

Postby runetrantor » Tue Jul 09, 2013 10:16 pm UTC

Can I ask the science-y community of this forum a related question? I have been trying to get an answer since Randall's other 'drain the oceans' comic (The wardrobe one)
Also, Yahoo Answers was useless. :S

Its pretty similar to the scenario Randall calculated, but the drain is 10 kilometers in diameter, and its just set at 20km depth in an ocean world, meaning hundred kilometer deep oceans (This whole thing is me trying to give another barren world oceans), and the other side of the portal is in a planet the size of Earth, with same atmosphere (previously added) and the portal is set laying down at the desired sealevel.

So no disconnecting seas to consider, nor anything. The pressure at the other side would still be lower, as the atmosphere of this world would be pooled in what would be the seas later on, so the portal is 'high' (5 kms? Or something?)
My question is basically this: Hold long would such a hole take to fill a world with a somewhat similar amount of water as Earth? Years? Too long? (If so, a 100 km portal would be capable of doing it fast?)

REEEEALLY sorry this sounds mad, but I really need an answer and I am running out of ideas of who to ask. (And you guys seem like the less likely to look at this idea weirdly)
I need it for a book.

Thanks in advance to anyone who can help!

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Re: What-If 0053: "Drain the Oceans"

Postby teelo » Tue Jul 09, 2013 10:39 pm UTC

I hereby claim the island just slightly north of antarctica (on the drained map) and name it Teeland.

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Re: What-If 0053: "Drain the Oceans"

Postby Diadem » Tue Jul 09, 2013 10:49 pm UTC

This gives a pretty accurate description of The Netherlands.

Did you guys know that Global Warming is actually a global effort to keep the Dutch busy with rising sea levels? The rising sea levels are needed to offset our technological progress, which would otherwise make our fight against the water easier every year. If you don't burn enough fossil fuels, the Dutch will conquer the world. True story.
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Re: What-If 0053: "Drain the Oceans"

Postby gmalivuk » Wed Jul 10, 2013 12:01 am UTC

runetrantor wrote:Can I ask the science-y community of this forum a related question? I have been trying to get an answer since Randall's other 'drain the oceans' comic (The wardrobe one)
Also, Yahoo Answers was useless. :S

Its pretty similar to the scenario Randall calculated, but the drain is 10 kilometers in diameter, and its just set at 20km depth in an ocean world, meaning hundred kilometer deep oceans (This whole thing is me trying to give another barren world oceans), and the other side of the portal is in a planet the size of Earth, with same atmosphere (previously added) and the portal is set laying down at the desired sealevel.

So no disconnecting seas to consider, nor anything. The pressure at the other side would still be lower, as the atmosphere of this world would be pooled in what would be the seas later on, so the portal is 'high' (5 kms? Or something?)
My question is basically this: Hold long would such a hole take to fill a world with a somewhat similar amount of water as Earth? Years? Too long? (If so, a 100 km portal would be capable of doing it fast?)

REEEEALLY sorry this sounds mad, but I really need an answer and I am running out of ideas of who to ask. (And you guys seem like the less likely to look at this idea weirdly)
I need it for a book.

Thanks in advance to anyone who can help!
In this what-if, there's a link to comic 969, which gives flow rate in terms of area and depth: http://xkcd.com/969/

Obviously there are complicating factors to consider, such as whether your planet is earth-sized and how the depth of the portal changes as water goes through it, plus the fact that water isn't really incompressible and so its density will change as you drain the water above it.

But initially, with a slightly higher (10m/s^2) gravity and totally uncompressed 1kg/L water even at your 20km depth, the water will go through at about 630m/s, or. 63km/s, which means 0.63km^3 per second for each km^2 of your opening. Since you have nearly 80km^2, it works out to a flow rate of about 50km^3/s.

With a rough estimate of 1.5 billion km^3 in our oceans, it would take about a year to fill them at that rate.
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Re: What-If 0053: "Drain the Oceans"

Postby teelo » Wed Jul 10, 2013 12:35 am UTC

Randall didn't answer the other side of his revised scenario - what happens to Mars!!?

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Re: What-If 0053: "Drain the Oceans"

Postby gmalivuk » Wed Jul 10, 2013 1:03 am UTC

It... gets covered with water?

Most people aren't terribly familiar with the topography of Mars as it is, so I think a similar set of maps for it wouldn't be as interesting.
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Re: What-If 0053: "Drain the Oceans"

Postby Josephine » Wed Jul 10, 2013 2:42 am UTC

teelo wrote:Randall didn't answer the other side of his revised scenario - what happens to Mars!!?

Here's the location of Curiosity on a topological map of Mars. Shouldn't be hard to figure out from there.
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Re: What-If 0053: "Drain the Oceans"

Postby runetrantor » Wed Jul 10, 2013 2:55 am UTC

gmalivuk wrote:Obviously there are complicating factors to consider, such as whether your planet is earth-sized and how the depth of the portal changes as water goes through it, plus the fact that water isn't really incompressible and so its density will change as you drain the water above it.

But initially, with a slightly higher (10m/s^2) gravity and totally uncompressed 1kg/L water even at your 20km depth, the water will go through at about 630m/s, or. 63km/s, which means 0.63km^3 per second for each km^2 of your opening. Since you have nearly 80km^2, it works out to a flow rate of about 50km^3/s.

With a rough estimate of 1.5 billion km^3 in our oceans, it would take about a year to fill them at that rate.



THANK YOU! You have no idea how much this helps me! A year? That's pretty good for terraforming, so I take it! XD (That would be the 10km one right?)

I lost count how many times I tried to calculate it myself only for the calculator to go TILT.
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Re: What-If 0053: "Drain the Oceans"

Postby Copper Bezel » Wed Jul 10, 2013 3:37 am UTC

What does it mean to go to tilt? I think I want that in my idiom.

Josephine wrote:Here's the location of Curiosity on a topological map of Mars. Shouldn't be hard to figure out from there.


Gah, I totally posted a thing before. That said, topography map is much more convenient than the one I was looking at, and having Curiosity's location marked skips a step. But yeah, the northern hemisphere just becomes one big ocean.

There's still the question of the temperature. I'm guessing that there's not remotely enough surface area per volume for freezing to slow down the water flow if the flow rate itself is high enough. It would likely be a problem with the 10-meter drain, but probably not for the adjusted flow rate - except that we don't know what that new rate is. If the flow was slow enough, I still wonder if it could be complicated by freezing and what that might look like. There's not a lot of atmosphere for cooling, but there's still conduction into the regolith. There's a point away from the portal where the depth would be low enough for freezing to happen at the same rate as the water flow, and ice could begin to pile up. That's not exciting, but it could lead to a different result than the "just look at the map" one.

It does look as if there's enough water to engulf the planet in a totally boring way (except for the highest peaks, like Klear said.) At least, there seems to be just about enough if we use all of the oceans (1.3-1.5e9 km^3,) and Randall says the remaining seas on Earth are shallow, so it's probably not a significant difference.

All that aside, there's something legitimately interesting to me, at least, in those maps: the entire northern hemisphere seems to be at a lower elevation than the southern. I'm curious how that works. Is this a result of uneven density in Mars' composition, such that it essentially has a "low" center of gravity? I know there's no plastic mantle to allow the surface to even itself out, but it's really quite weird.
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Re: What-If 0053: "Drain the Oceans"

Postby gmalivuk » Wed Jul 10, 2013 3:46 am UTC

Yeah, evidently the center of mass doesn't coincide with the center of a uniform body with the same surface.
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Re: What-If 0053: "Drain the Oceans"

Postby Bossi » Wed Jul 10, 2013 4:02 am UTC

(MARS)
As others noted- surprised this didn't delve into what happens on Mars! Perhaps it's just not as familiar a geography... but it'd be curious to see the existing geography become inundated & the impacts of erosion about the portal, as well as how the water would react to the temperature/pressure & could it affect it into the long-term; perhaps a denser atmosphere; increased pressure; a thicker blanket.

(GROUNDWATER)
Also curious about the effects to groundwater- how much would reach the drain, would it enable landlocked areas to drain, and what degrees of land subsidence would current & new-found land experience.

(MOON)
Also wonder if we drained to the Moon, how the presence of lunar oceans & the tidal pull would not just affect the Moon, but how they'd affect the orbits & rotation of the Moon about the Earth.

(GO WILLIAM)
Also... I'm definitely turning either the 1km or 2km maps into Civ3 levels.


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