A world with Freshwater Oceans

So... I was thinking of a world where most oceans have freshwater and I was wondering if there is any large echological effect from that? I was thinking the freshwater-ness is actually magically created.

The oceans are saltwater because of geology. They are literally the rinsings and the dissolved chemical soup of the earth.

Freshwater erodes the land and dissolves chemicals like calcium, iron and sodium and carries it to the sea, the sea adds in those chemicals and owing to equilibrium attempts distributes it across. The sea cannot precipitate or ecologically recycle those chemicals and salts out faster than it comes in.

Then you'd have a whole different baseball game when it comes to climate. Freshwater and seawater don't behave the same when it comes to temperature variations, creation and maintenance of currents and their effect on passing weather systems.

And then you'd have the problem of winter. Freshwater freezes at a much higher temperature than seawater.

It's nowhere near an "ocean", but the Great Lakes are all freshwater. If you need a model for how it affects the weather and the life around it, that's the closest you're gonna get. But even then, it's only in one climate zone.

But like Major Tom said: It'll be pretty hard to pull off, and it would do hell to the ecology. Water makes up a huge chunk of all life, and the higher freezing-point of freshwater makes it that much harder for life to survive in the oceans, especially in the winters.

Is the entire planet covered in water? I mean you could have a planet like that, just without salt deposits.

I was thinking that the world has a lot of rivers (possibly the entire thing is a result of magic going wrong) in moutain valleys.

I might write off the idea of Freshwater oceans if they are "that" difficult, and maybe invert it: There is a lot of freshwater rivers an lake systems around, with a few super-saline oceans where all the salts end up. Ecologically, it sounds more extreme, but more... sustainable.

^ You can also do a glacial period. For example Lake Lahontan in the Pleistocene glacial period was the size of a small sea.

Fresh water freezes, but only to a point. Wet lands never completely turn to ice, as water always mixes with something to offset that, universal solvent and all, plus it gets harder to freeze as more of it build up at the bottom, plus, ice and show themselves can act as insulators of sorts, ironic as that sounds.

Plus, winter doesn't hit the whole planet at once. Something will always be uncovered, allowing co2-o2 exchange and all that. In fact, the radically altered state of winter on the ocean could make for some interesting animals and migrations. A lot more aquatic life (and it'd be aquatic on account of the lack of salt) might be situated around the equator...though cold water is actually better for most organisms since warm water doesn't absorb gas too well(being closer to the state of gas itself and all), I don't really know. Definitely have to take into account the hypertonic environment(superficially, a lot more catfish in the oceans instead of sharks, ect)

I guess the ice bergs on the poles would be a lot larger too. Glaciers might be more common. I'm assuming the currents are going to be completely different, though I don't know in what manner they would be.

The base makeup of the rock/ground might be different too...or maybe even the air? Some agent that reacts with chloride/chloride perhaps? You know, if the oceans don't have salt, is it even necessary to life on this planet, assuming life on this planet also developed in the ocean? Have the oceans always been free of salt, or has this come in the last billion years or so?

edited 22nd May '15 1:23:58 PM by IndirectActiveTransport

You've never seen a pond or river freeze completely through after a few nights of -30C have you?

True very large bodies of freshwater are extremely difficult to freeze all the way through but typically if freshwater exists you're in a climate range that is never cold enough to freeze very large amounts all the way through. Of course there are the oddballs like the subglacial "lakes" in the Antarctic which are liquid water, surrounded by upwards of thousands of meters of ice in most directions.

Not all freshwater drains out. What about lakes?

Lakes don't generally last long enough for that to become an issue. We're talking about geological timescales here. Lakes tend to have what you might call a natural lifespan. Cycles of plant growth and sedimentation will eventually turn a lake into a bog, and then finally dry land.

There's a number of extremely long-lasting lakes (generally in areas with very little nutrient inflow), and you'll find that those either have higher salinity than you'd expect from a freshwater lake or that there's an outflow ensuring that salinity levels remain balanced.

Really? So every lake will one day dry up? Even the Great Lakes?

Barring other geological events interfering with the cycle...yes. It's a major source of fossil fuels, incidentally. A lot of those deposits weren't ancient seabeds, they were lakes that got filled up with organic detritus and sediment.

As a matter of fact, in many lakes this process can actually be observed...if you look at reeds over the span of a few decades (photographs tend to tell the story pretty well) you'll notice how the reeds keep "wandering" ever further into the lake while areas that used to be full of reeds are now more or less dry ground.

edited 24th May '15 12:09:36 PM by MattStriker

Actually, I have seen a river stop flowing, wasn't thinking of them when I typed wetlands, shouldn't have said that. Never seen a pond freeze completely through.

That is one way currents will be different. Some of them may periodically stop completely.

Parasitology would probably be pretty interesting, given more animals will be able to drink straight from the ocean.

That raises another interesting point, actually...the oceans wouldn't be as much of a barrier between ecosystems as they are in our world. Aquatic species might be pretty uniformly distributed all over the planet (well, with variations by climate and biome). You might get the same fish-analogue in a river on one continent as in another one on the other side of the planet. That would also slow down aquatic speciation a bit, so you'd probably see a bit less diversity than we do.

huh, given all these circunstances, I think my new idea is to have the world being created magically the way it is and have some other magical mechanism that keeps salinity slow (possibly a part of the ocean that collects the salt?)

my other idea is having the magic user responsible for the entire thing being a very early human and have the process going for long enough that it didn't cause a mass extinction event.

What you guys think? What variation of A Wizard Did It makes more sense?

Gonna be a little blunt, here (sorry in advance) but by saying A Wizard Did It, you're delving into one of the Seven Deadly Sins of Worldbuilding. Specifically, number 7: Introducing some superpower, like magic or insane tech [or changing your planet's geology], without fully accounting for how it would change society [or the planet].

If your planet's oceans are all freshwater, that changes the initial conditions for life to begin. Which means you'll completely change the way life works on that planet. Even freshwater fish need salt in their bodies. Example: Bones exist to store calcium, an adaptation from when animals first went into freshwater and onto land, away from the calcium-rich sea salt. So do vertebrate animals exist in your world? If so, why? How? If not, what kind of sapient Starfish Aliens populate your world?

This is one of the biggest traps I've come across in worldbuilding. If you change one fundamental aspect of our planet, you'll open up a massive can of worms to justify the change. Yes, it can be done. But to do it well (as in: without lazy hand-waving) you'll have to research a ton of different stuff to make it work.

In your case, that means a crash-course in weather, geology, hydrology, biology, and a slew of other topics I can't even begin to name at the moment.

In other words: I wouldn't do it if I were you, but good luck.

edited 24th May '15 6:50:40 PM by AwSamWeston

Sorry, if I sounded dismissive, I was aiming at self-decriptation.

The thing is, I'd like to constrain changes to an... "aesthetic", the idea of a fully scientifically consistent world of freshwater ocean is interesting, but might not fit what I want for the setting looks.

In particular, I want to be scientifically accurate about how freshwater affects: weather, geology, hydrology but I don't like "aesthetic" of Starfish Aliens swimming around.

New flora and fauna are great, but should still be recognizable, my solution was making the change in the planet's ocean being somehow recent or part of a greater design. Since that would explain why you could see recognizable-but-adapted-species around. Unless I am missing something...?

New aesthetics are always a good idea. But if that's the case, I'm not sure what "freshwater oceans" would do to help that. I mean, saltwater and naturally-occurring freshwater both have similar levels of murk/clarity. Maybe you could let characters drink when they're out at sea, but otherwise I can't see much difference between the two — which leads me to think it's not worth the change.

On top of that: if you say "the oceans are freshwater," you'll inevitably have someone nitpicking that detail. In this case, that someone is me.

(To be completely fair, "scientifically plausible" is just one of my creative preferences. You can go with A Wizard Did It if you really want.)

Can't help you there. I don't know nearly enough about geology, physics (or just math) to begin to scientifically explain artificial planet creation.

Well, maybe just a little. If you're using transplanted organisms, or the people who made a planet had a hand in the development of life somehow, familiar forms wouldn't be out of the question, while still allowing the process of evolution to create some new morphs and what not.

Eventually. Geology and geography changes over a long enough time span. The American Southwest in the last Ice Age had a number of Great Lakes and smaller analogues in Lake Lahontan, Bonneville, Missoula and more.

Yes the same American Southwest that today is dominated by rocky mountains, steppes and deserts.

All those lakes dried up as the Ice Age ended and the glaciers pushed back north. Several of them like Missoula and Bonneville had some absolutely epic floods happen because of natural means before that.

Oh yeah, and not many of them had outflows. Most of the region is what is considered endorheic, or having no means of drainage except through ground seepage or more commonly evaporation. The vast quantities of salt flats in the American Southwest are proof of this. Some of those lakes did have drainage to the Colorado River (pretty much THE sole drainage outlet to the sea in the Great Basin region besides the Snake River in Idaho) but shifts in geology and geography owing to things like erosion, floods, earthquakes and more isolated some of them.

As for the Great Lakes? They've never been smaller since the last glacial period. Sedimentation, natural climate change and more are little by little taking them away. Assuming a new glacial period doesn't rebuild or expand them, in the course of the next 50 million years or less, they'll completely disappear like many other lakes and (inland) seas.

Why do they say Lake Baikal is the oldest lake in the world? Surely there must have been others before it.

longest lived maybe?

Making a pure freshwater world seems... daunting.

Making low salinity world seems to be more... approachable. Maybe by having multiple ice asteroids?

I wonder how the carbon cycle would pan out. Unless you have a more alkaline (and thus likely saltier) environment to support calcite/aragonite producing lifeforms, Ca Co 3 may be in short supply.

edit- Calcium carbonate I meant, not Cobalt. Damned shift key sticks half the time and doesn't register the other half.

edited 31st May '15 6:41:06 PM by carbon-mantis

Calcium Tricobalt?