Watery world

Alright so I was thinking of making an Ocean punk style world where water has basically flooded globally. I was thinking very little landmasses exist as islands.

What's got me stumped are a couple of things: What kind of events could lead to such a world, how would it affect society and the already present ecosystems (besides the obvious mass extinctions), and what sorts of new dangers do these present?

First off, what kind of tech level are we talking about? If it's mostly primitive salvage then you want to watch Waterworld (1995).

If it's more advanced tech you might want to play Subnautica.

One danger you really have to watch out for. Cyclones. Shallow seas formed by flooded continental shelves are great breedings grounds for tropical storms and the longer they stay over water the stronger they can grow so you can expect to see more of them and larger ones.

If this is a relatively sudden event this is going to be the perfect breeding ground for future oil deposits but in the short term your probably going to get fairly oxygen starved conditions at the bottoms of the flooded contents caused by masses of rotting plant matter. Depending on how well the surface and lower waters mix you could actually see short term marine die-offs due to oceanic oxygen levels dropping.

Let's say pretty average modern tech, neither far past or far future.

Edit: By that I mean before the flooding

Edited by sifsand on Jul 15th 2019 at 4:59:43 AM

The simplest way to get a flooded planet is rapid climate change. It doesn't have to be man-made, although that is obviously the way we're going in this world.

And as for how humanity would cope with such a catastrophic event?

Would traditional economy still be a thing or would we revert to bartering?

If we assume climate change then there would be years or even decades to adapt to the change. Submerged nations would be well equipped to deal with their new circumstances.

Modern nuclear submarines seem like a good model for a high tech underwater existence. Electrolysis for oxygen production and reverse osmosis filters for water. Only thing that you need to cover is food.

On the more rural side of the scale, you can farm kelp and fish economically today so I suspect that this would monopolize the industry. Drinking water can be filtered from rainwater. The biggest issue is a lack of building material as trees would be effectively extinct and coral doesn't have the right mechanical properties for boat building.

For one thing the earth would need alot more water, even if all ice on the planet melted there would still plenty of land.

Also, such a planet would by necessity be much warmer than today's Earth and subject to much more violent weather events. Equatorial regions might well be uninhabitable, or at least unable to permit sustained human water travel. Without land to break them up, you could have hurricanes lasting months.

Edited by Fighteer on Jul 15th 2019 at 10:40:28 AM

Let's not forget classics of this subgenre;Sea monsters!

What kind of new aquatic life can we expect to find now that they have practically free reign.

Umm, not many. Evolution, especially of large animals, works on time scales much larger than you'd find in a typical post-apocalyptic story. Humans, even in an After the End scenario where high technology is lost, are still very good at hunting and killing large animals: we are apex predators of almost any ecosystem due to our ability to build and use tools.

There are also biochemical effects of warmer oceans to consider, which could cause all sorts of interesting problems for marine life such as oxygen depletion, algae blooms, and similar things. I'd be surprised if a lot of large sea life stayed dominant (never mind alive) for long.

Hmmm, if that's the case what kind of marine life could survive it?

I believe warmer oceans was the reason marine reptiles were so prominent in the mesozoic, they breathe air so lower levels of oxygen in warm water was less of an issue.

Yeah but you're talking millions of years to re-evolve those huge species, assuming that humans don't kill everything bigger than a dolphin.

Humans are able to be apex predators in the ocean because of a preexisting infrastructure back on land, if that infrastructure disappears in a flood than killing large marine creatures on a mass scale would be a significantly harder task.

Obviously you can handwave it, but the biggest question is inevitably going to be where all that water came from. To cover the planet to the top of Mt. Everest in the vein of Waterworld you’d need an estimated 4.6 billion cubic kilometers of water, which is three times the amount of water that currently exists on the planet in any form.

An early draft idea I had involving practically non-stop rain but I kept it in mind until I thought of something better.

Also, what if the land wasn't completely submerged, there'd be scattered islands and the really big structures would still be above water.

Rain is water moving from one place to another. The total amount of water in the Earth's biosphere doesn't change.

If humans become completely aquatic with no land-based infrastructure, it is quite possible that we'd go completely extinct. If we can still grow food, build ships, and so on, then we'd probably do fine.

Rain doesn’t add or subtract any water from the planet, it just moves it around.

If the ice caps melted entirely you’d get a sea rise of about 200 feet, but that wouldn’t be enough to make a totally watery planet. There would still be continent-sized landmasses. You’d have plenty of flooded cities, but you probably wouldn’t see people transitioning to aquatic modes of living.

Edited by archonspeaks on Jul 15th 2019 at 8:25:10 AM

I'm just gonna go with Archons siggestion to handwave it since I can't properly explain it.

Asteroids? I figure a great big chunk of interstellar ice can account for the shear volume of water but said asteroid would also wipe out life as we know it if it collided.

Aren't asteroids made of rock and ore?

Some are, although that's a loaded question since ore is any mineral that's profitable to mine.

But many asteroids past Mars have some ice content and we know that Comets often have lots of ice in them.

An ice comet large enough to add four billion cubic kilometers of water to our biosphere would kill all life on the planet if it impacted. It'd be about a thousand km in radius... insane.

Edited by Fighteer on Jul 15th 2019 at 12:40:56 PM

At that size it might be able to make a fissure all the way to the earth's mantle.