scrape_r_rational/data/cache2/2tuqpg.md

Help with global effects of a continent appearing in the Pacific Ocean for a story

• Author: u/Threedoge New Lunar Republic*

• URL: https://www.reddit.com/r/rational/comments/2tuqpg/help_with_global_effects_of_a_continent_appearing/

• Score: 10

• Created: 2015-01-27T16:32:47

Post:

Alright so here's the basic out line. Magical race from another universe is under threat, so they decide to move their entire continent somewhere else. After doing a quick scan of the multivierse they find a planet with similar atmospheric conditions and large bodies of water. Archmages cast the spell and boom multiversal continent transfer complete. (Whether or not moving your entire continent is the smartest move is debatable, since they assume that any world teleport to would not have the plants and such that they could eat, and don't have the time to create a seed bank or something similar.)

Turns out the planet they moved it to is ours, and here's the question. If a continent that was about the size of the continental US (around 8 million kilometers^2 in size we'll say) iterated with the the Pacific plate, displacing (not destroying or converting it) any water and atmosphere, what would the effects be?

I've been able to figure out a rough estimate of how much the sea would rise (its about 95 meters globally, give or take a few meters) but I don't know what effects it would have tectonically or how it might affect weather/atmospheric conditions. Does anyone have a better background in this that might be able to help me out?

Edit: not kilos kilometers, those are rather different

Comments:

u/alexanderwales [+9] Time flies like an arrow (an hour later)

That's such an extreme change that I'm not sure existing models are going to help too much. You start off with a tsunami far, far worse than anything in human history, which destroys human civilization as we know it and kills at least half the population, and then the sea level rising floods out every single coastal city.

In terms of weather, it depends on where exactly your continent gets placed in the Pacific. Check out this XKCD what if which goes into some details about how the world would change if it were flipped on its side, since he goes into some detail on how the climate would be affected. Are you placing the continent so that it disrupts the jet streams?

But mostly, any concerns about weather are going to be overshadowed by the fact that your proposed scenario is wiping out a significant chunk of life on earth.

u/Threedoge [+3] New Lunar Republic (3 hours later)

And once again XKCD proves to be relevant. Thanks I hadn't seen that one, and yes coastal/near coastal settlements seem to number around a billion individuals, though I still need to see if there is a better way to sample that. And its also the underlying conflict of this story, to see if it would even be remotely possible for this group to redeem themselves in the eyes of our populous.

u/duffmancd [+1] (3 days later)

This paper estimates that in 1994 1.88 billion people lived below 100m elevation. You could probably update that with todays population by taking the percent (about one third). It also has some nice images visualising the areas most likely to be effected unfortunately at the <500m rather than <100m level.

With at least a third of the worlds population killed (due simply to being underwater) and many more likely due to the mega-tsunami and complete breakdown of society our continents will be basically post-apocalyptic. Land invasions kill a smaller percentage of population. I read an article somewhere talking about Australia, where if 20% of truck drivers got sick at once it would be completely impossible to supply the country with adequate food. Remember also that in many places industry is located near ports, so most manufacturing capabilities will be wiped out. Currently it takes at least a couple of months for a new factory to be built, toolled and begin producing. In the post-apocalyptic devastation it will be years or decades to return to current capabilities.

u/OffColorCommentary [+1] (10 hours later)

I noticed a couple things on the XKCD map that I thought were worth sharing:

• The South American desert would probably be smaller, mostly confined to the east side of the continent, and further south (not bordering the ocean, but bordering the ice area). The polar desert would slowly turn into a taiga, like Siberia.
• The Himalayas are frozen. Much of the reason India and China have such huge populations is because of rivers fed by runoff from the Himalayas, and we have no new mountains that size moving into temperate zones to make up for it. This planet's population is ~2 billion less than ours.

u/eaglejarl [+7] (an hour later)

I would try submitting this one to What If XKCD. Seems right up Randall's alley.

I don't know the effects, but some things I'd look for:

• Plagues resulting from the numerous dead bodies where you just killed most of the human race
• Total collapse of human civilization due to deaths and destruction of infrastructure.
• Disruption of ocean circulation leads to temperature changes in the ocean causing massive weather changes and die offs
• Reduced ocean area means less evaporation there, but other areas are now flooded. Total area to evaporate from has gone up, so the weather gets wetter
• Depending on where it arrives, the new continent could end up spanning the boundary of two continental plates. This could lead to more vulcanism and might, over geologic time, tear the new continent apart.

u/Threedoge [+1] New Lunar Republic (3 hours later)

In order:

Oh yes water borne pathogens would be on the rise as a must. Airborne as well but probably not to the same extent. Also while a large portion of humanity lives by the coasts its no where near 75%. Probably closer to 20% if 2010 records are accurate.

Ehhhh probably not. It would be a MASSIVE shift, with a lot of nations probably devolving into smaller totalitarian states ruled by a harsh dictator. Not to mention technology would take a hit for a long while, but I don't think its the infrastructural that we have to worry about(well yes worry about it, since seaborne travel would basically be gone for the next decade or so, but its only around 3rd or 4th place).

This combined with general weather change is rather high up on the list, though I'm not sure how it would effect farmed animals (cows, chickens etc.) probability not to the same extent as it would birds and other wildlife. Depending on just how intertwined the webs are it might be a while before coastal ecological systems begin to affect more inland ones.

And it should arrive smack dab in the center of the Pacific plate, which means I need to revise how this is going to affect Hawaii, but that where I run into trouble. I don't know just what that kind of pressure would do to the magma oceans. I mean ya it going to trigger volcanos, but what about earthquakes? Will it forces other plates to do... something? I've got next to no clue there.

u/OffColorCommentary [+3] (9 hours later)

Are you sure you want to displace the water instead of doing some sort of swap?

Without the sea level changes and massive tsunamis, you're still looking at a giant mess. The new continent will completely change pacific ocean currents. To get a sense of the scale of what ocean currents do to our climate - England and Siberia have the same latitude.

What the new currents would shake out to after adding a continent is beyond prediction for now. You can count on ending all the known effects (like the extreme mildness of US's west coast), but there's no telling what new ones we'll get. I'd bet on warming up Alaska (to England levels) and generally cooling down Australia, but that's a shot in the dark.

Places with sudden warming will experience flooding, and places with sudden cooling will have deaths due to exposure and wide-scaled infrastructure shutdowns (Australia does not have snow plows). Everyone who has crops will lose them, and so many plant species will die off that we might have to start importing ones appropriate to the new climates once things settle down.

But that's all post-change. It'll take a long time to settle all that water into a new cycle, and until it does you're going to have rapid temperature shifts, which means rapid changes in air currents, which means hurricanes and tornadoes. The eventual power of hurricanes (not tornadoes) will quickly go down since the new oceans will be smaller, but the big ones triggered by the sudden change in equatorial flow will suck.

u/duffmancd [+1] (3 days later)

Australia has bigger problems. 85% of the population lives within 50km of the coast and all the major cities are ports. (Yes, not all of those 85% will be below 95m but a heck of a lot will be).

On the bright side, the central Australian desert will become the central Australian sea, making the inland side of the Great Dividing Range much more pleasant for new settlers.

u/OffColorCommentary [+1] (3 days later)

That's true in other scenarios, but everything I wrote above starts with the suggestion that the mass is swapped. There's no sea level change in that.

Just massive climate shifts, hurricanes, and, as someone else noticed, probably earthquakes and triggering most of the world's volcanoes even if the swap is gentle.

u/duffmancd [+1] (3 days later)

Ah, sorry I somehow read "without" as "with" in your second paragraph. My fault!

u/FaceDeer [+2] (an hour later)

If the archmages know the water's going to be displaced rather than destroyed or "swapped", they'll know that their own continent is going to see major flooding as well. Will they be able to calculate how much by? They could perhaps raise their continent by that amount when they make the transition.

How rapidly is the water displaced? If it's "instant" the resulting tsunami is going to be incredible, will probably kill billions. It'll also screw over the arriving continent, so again, the archmages will need to account for this.

Do they know the destination world is inhabited? If so, they're deliberately making a choice to kill billions to save their own skins. They're going to be seen as history's greatest monsters. Even if it's accidental, expect the whole world to hate their guts. How well does magic fare against nuclear weapons and so forth? Could get reeeal ugly unless they fall all over themselves trying to help fix the mess they made.

Does it overlap any islands in the Pacific? What happens to them and their inhabitants? Probably small potatoes compared to the flooding, but it'll probably matter if they wind up with Hawaii embedded in the middle of their land.

u/Threedoge [+2] New Lunar Republic (3 hours later)

In order:

Yes they do know that it would cause some flooding for their land mass, and the intimidate secondary spell that would be cast is one that would basically create large walls of force to create a flood wall around the continent (there will be some flooding because the universal tunneling spell would have to finish first before they could work on the second).

Not instantaneous, I would say about a three day period.

No they don't have a clue that its inhabited. They know that the world has a rich nitrogen/oxygen atmosphere and large bodies of water, and that its in the goldylocks zone. Everything else is a mystery to them.

Yes it would, for lack of a better term, swallow smaller landmasses, though if I'm positioning this thing right it wouldn't eat Hawaii. I think, need to run those numbers again.

And finally yes, what they are doing is going to be considered an atrocity by basically everyone. We're talking about wiping out nearly a billion or so individuals in just the initial floods, let alone what famine/oil scarcity/god knows what else.

u/Lethalmud [+1] (an hour later)

Here's a map showing the results of rising sea levels, although it only reaches up to 60 meters rise. But on that point already you can see that America will lose a lot of land on its east coast, including New York city and most of florida. Europe will loses the netherlands and denmark first,. In the east, Bangladesh will disappear completely. And china will have its most populated area's flooded, losing both Beijing and Hong Kong. Australia might become a little more habitable, getting a nice inland sea, all they have to give up for it is Melbourne.

This is all ignoring the Massive Tsunami that would Ravage all the pacific coasts, probably taking out most of japan, indonesia, the Philippines and a bit of china, as well as the Americas Western coasts. As all this would happen pretty instantaneous. There will probably be no concentrated rescue efforts, because most countries will be too busy saving themselves.

Then there will probably be some long term effects as gulfstreams are altered and climate patterns with that. Causing rain and drought periods to change worldwide. And maybe some geologic changes too?

u/Threedoge [+1] New Lunar Republic (3 hours later)

Ya its the geologic that's stumping me. I know that something will occur just not what it might be. Volcanic eruptions are likely due to added weight placed on the mantel(? I think was the name of the layer), but no so sure about earthquakes and how severe the eruptions might be.

u/Farmerbob1 [+2] Level 1 author (10 hours later)

Putting a continent's worth of mass on the Pacific Plate would certainly impact tectonics. It could even be enough mass to break off the crust it lands on into a new, separate crust, surrounded by the Pacific Plate.

If a new plate is formed, that new plate would then settle into the Earth, slightly. It will displace magma. The entire planet would expand slightly due to the displacement of magma. Every active tectonic boundary on Earth would shift, opening up slightly as the crust of the Earth expanded.

Imagine every single active tectonic plate as a continuous volcano along its entire border.

EDIT: Actually the expansion of the Earth would probably happen anyway, no matter where the continent is placed, no matter if the plate under the new continent broke. The plates float on the Mantle. Literally float like boats. Added mass means added displacement no matter how you calculate it.

u/Lethalmud [+1] (4 hours later)

I wanted to say try /r/askgeology but that subreddit is dead.

u/Farmerbob1 [+1] Level 1 author (3 hours later)

It displaces what is there? Nearly instantaneously? Both air and water? Uh. We're talking about a dinosaur killer impact level of energy generated.

u/Threedoge [+1] New Lunar Republic (4 hours later)

Not instantly, over the course of three(ish still got to pin that down) days. Also the atmosphere would be displayed really slowly, though it might still cause some rather gusty winds and crazy large storms.

u/Farmerbob1 [+1] Level 1 author (4 hours later)

The political shifts in the world are going to be rather extreme, and should be considered. A new continent in the middle of the pacific with massive flooding... Whatever political entities survive sufficiently intact to continue to govern are going to almost certainly be up to some serious backroom politics, no matter what they tell the newcomers.

Developed countries who were able to preserve a lot of their population by moving them inland and to higher elevations are going to be looking for places to put those people. A lot of third world countries with higher elevation land are very likely to be, ah, encouraged to accept immigration.

If these mages are powerful enough to move a continent, they are almost certainly going to be asked if they can implement some sort of massive freeze at the poles, to suck water out of the oceans and restore land.

u/Bowbreaker [+1] Solitary Locust (a day later)

How exactly does this slow displacement work? Does a third of all of the continents molecules appear gradually each day or something?

u/xaleander [+1] (a day later)

If you don't switch the matter but displace it, my (limited) understanding of physics tells me that it would be the greatest explosion there ever was. I don't know whether the biosphere would survive after that....

u/Solonarv [+1] Chaos Legion (2 days later)

Depends on how exactly you do it. Being a highly advanced race, they would be able to predict such an effect, and may adapt the spell for that.

The spell could at first create a tiny vacuum surrounded by some magical barrier, which would then expand at a semi-reasonable rate until it had cleared out all the space required for the transfer.

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