3.2 billion years ago the Earth may have looked a lot like Kevin Costner’s ‘Waterwor

[Lazy1]

I guess a "Water world" would be salty and effect what potential species could develop or survive. We would need a bunch of water makers.

[GordMay]

According to the U.S. Geological Survey, there are over 332,519,000 cubic miles of water on the planet.
Of this vast volume of water, NOAA's National Geophysical Data Center estimates that 321,003,271 cubic miles is in the ocean.
A cubic mile of water equals more than 1.1 trillion gallons.
I still don't know how many terrestrial impacts it would have taken to transport "most" of this water to Earth.


Salt in oceanic waters comes from rocks on land.
The rain, that falls on the land, contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water).
As the rain erodes the rock, acids in the rainwater break down the rock. This process creates ions, or electrically charged atomic particles. These ions are carried away in runoff to streams and rivers and, ultimately, to the ocean. Many of the dissolved ions are used by organisms in the ocean, and are removed from the water.
Others are not used up and are left for long periods of time where their concentrations increase over time.
Two of the most prevalent ions in seawater are chloride and sodium. Together, they make up over 90 percent of all dissolved ions in the ocean. Sodium and Chloride are 'salty.'

[Singularity]

Originally Posted by Singularity

Hard to imagine that the moisture in our expiratory breath could ever amount to much, but given enough biomass it can create oceans. Without water, you can't have life...period. But once you get a smidgen of liquid water...if some amino acid legos vibrate together to create life...then the life starts producing more H2O (and CO2).

But life-produced CO2 isn't enough per se to create an atmosphere, and so it might help if you've got some volcanoes/vents outgassing; if/when these outgasses act to trap solar energy and expired H20 from microscopic life below...you get more ice melting, more melted water more microscopic life, more conversion of O2 to H20 by the life forms. Rinse and repeat for a few billions years=oceans. Maybe/probably.

Studies of earth rocks and asteroids finds similar compositions...in other words the cloud that coalesced as the earth likely had enough molecules on board to give us much/most of the water we have (i.e. not meteorite dependent).

Horribly incorrect logic/wording, the corrections appreciated.

To be sure life didn't produce the ocean's water, but the point I intended to make is that with the goldilocks atmosphere life begets more water...that life can/will induce a positive feedback loop produces an atmosphere that can hold more water (from small scales on up), otherwise reducing sublation/loss of H2O from the environmental substrates to space. In the macro scale, this is ordinary and the main culprit for AGW as endorsed by the American Chemical Society:

It’s Water Vapor, Not the CO2
https://www.acs.org/content/acs/en/c...t-the-co2.html
It’s true that water vapor is the largest contributor to the Earth’s greenhouse effect. On average, it probably accounts for about 60% of the warming effect. However, water vapor does not control the Earth’s temperature, but is instead controlled by the temperature. This is because the temperature of the surrounding atmosphere limits the maximum amount of water vapor the atmosphere can contain.

[toddster8]

I used to run with that crowd, 20-30 years ago. (Definitely more as a spectator than a participant in things geophysical though.) Gradually sort of lost touch after I "retired" from academic life. But anyway, a few tidbits, for context. Without stopping to, you know, actually put effort into looking up anything.

It's amazing how much people have deduced from very little evidence. Since all of Earth's surface has been recycled many times, there are very few rocks left from Archaean times - just a few scraps that got pushed up onto continents while most of the crust is continually subducted and recycled. Sometimes just a few crystals that survived the melting of the crust they were in and came back to the surface in younger magmas. So to a large extent, our knowledge of Earth's earliest times remains tentative.

The comet/asteroid water balance is plausible and was the leading theory as of a couple decades ago. There was still (IIRC) a lot of uncertainty about how much water was stored in the mantle. One key bit is that there was a lot more junk floating around early in the solar system, and a lot more impacts back then. Most of that stuff has been swept up by now, mostly into Jupiter. The other factor is time. Really hard to wrap one's head around the vast amount of time we're talking about. Trust your calculator, not your head.

Before about 3.8 billion years ago, there were no oceans. Too many impacts and too much heat for for liquid water to exist on the surface. Or if it did, the entire ocean was periodically vaporized and the atmosphere turned to steam. Processes worked very differently at that time, than they do today. (This was called the Late Heavy Bombardment - we know about it mostly from counting craters on the Moon and the ages of rocks brought back by Apollo missions.) Lots of Earth's surface volatiles were lost then, and possibly also at the time of the (putative) moon-forming planetary collision at 4.5 billion years.

So this paper is about what things were like a bit after the planet cooled down from all that excitement, and during the time when we have the first good evidence for the existence of life. But it's still just a snapshot in time.

[a64pilot]

Ref the impact theory of water the answer of how many impacts will never be known as it depends of course on comet size, but Billions would be a likely number.
But also one need to consider that the BIG gravity wells would suck up most debris floating around and therefore Jupiter and Saturn should be water worlds as they would have by far gotten the majority of the water.
So where is all their water?

[RaymondR]

Goldilocks zone, liquid water.

There could be masses of it as ice in or on the outer planets. Asteroid belt, rings of Saturn etc.

Lot's of land movements in 3.8 billion years with plate tectonics and the earth cooling. Maybe the spot they picked to investigate is just a fragment which did happen to spend a lot of time under water.

[Singularity]

Originally Posted by a64pilot

Ref the impact theory of water the answer of how many impacts will never be known as it depends of course on comet size, but Billions would be a likely number.
But also one need to consider that the BIG gravity wells would suck up most debris floating around and therefore Jupiter and Saturn should be water worlds as they would have by far gotten the majority of the water.
So where is all their water?

My understanding is to first conceptualize water in its most locally (our solar system) prevalent state...solid/ice. Frozen H20 is all over the place, this is not really in dispute. It just takes the right pressure and temperature conditions to allow it to exist in its liquid/water state. But H2O is all over, and indeed Jupiter (for example) has lots of H2O.

So to say that Earth has more water is simply saying that Earth has the temperature/pressure conditions to allow H20 to exist as water...contributing to our Goldilocks/Class M planet conditions. Of course the Earth is just coalesced stuff in the first place such that it becomes semantics to say what is "Earth" vs "meteorite."

[MicHughV]

I just find these figures to be laughable.....why 3.2 billion years ??
..that is, 3,200, 000,000 years.....why not, 3,190, 423, 678 years....is that any more believable ??? ....what is a mere million years here and there...or even 100 million years here and there ??
If one is going to throw out wildly speculative numbers...isn't 1,000, 000 pretty speculative ??? Sheesh, we (humankind) can't even agree to as to what happened 2,000 years ago....never mind 1,000, 000 years......and that is a mere 1 million.....now we are talking billions.
It would probably be more accurate to just say " a long time ago...we think this is what could have happened" or " we surmise this could have possibly happened"...etc.
Humankind still hasn't come to grips with the origin of mankind...a mere few 1,000 years ago.....about a minuscule percentage of 3.2 billion.

Off course...when someone says" it may.....it also implies " it may NOT"...."may" just being another acronym for a wild arsed guess...

Quite frankly, I don't think mankind has even a remotest clue as to the origin of water.....earth...our universe...etc.....

Not trying to put a damper on this topic, but trying to reign in these wild arsed guesses.

[Lazy1]

Maybe now we should discuss quantum astrophysics or other things that are unproven

[a64pilot]

Originally Posted by Singularity

My understanding is to first conceptualize water in its most locally (our solar system) prevalent state...solid/ice. Frozen H20 is all over the place, this is not really in dispute. It just takes the right pressure and temperature conditions to allow it to exist in its liquid/water state. But H2O is all over, and indeed Jupiter (for example) has lots of H2O.

So to say that Earth has more water is simply saying that Earth has the temperature/pressure conditions to allow H20 to exist as water...contributing to our Goldilocks/Class M planet conditions. Of course the Earth is just coalesced stuff in the first place such that it becomes semantics to say what is "Earth" vs "meteorite."

Jupiter is I believe 1/4 of 1% water, it should be much higher if the source of water was billions upon billions of Comets whether they were captured in the Solar system or not, the largest gravity wells, to include the largest of course would have captured the vast majority of them.

I don’t propose an alternative theory of the source of all the water, but since I was a kid I have always wondered about it. Sure seems to be a shed load lot of water.
71% of the Earth’s surface is covered at an average depth of over two miles.

[Kelkara]

Originally Posted by a64pilot

Sure seems to be a shed load lot of water.

Hydrogen and oxygen are two of the three most abundant elements in the galaxy ... a shed load of water ought to be expected.

[Reefmagnet]

To put it into context, surface water represents only 0.02 to 0.05% of the Earth's total mass.


https://www.universetoday.com/65588/...arth-is-water/


I'm not a big believer in the comet theory. I think the water has mostly originated from the interior of the planet. Volcanoes, for example, produce copious amounts of steam. I've always thought of Earth as having dual "atmospheres". The top atmosphere is obviously comprised of gas and the lower atmosphere is composed of liquid. In this context it makes sense that the lighter gases would form the gaseous atmosphere and the intermediate liquids would form an intermediate layer and then the solids would comprise the crust. It's simply a stratification of the three (common) states of matter.

[RaymondR]

Originally Posted by MicHughV

I just find these figures to be laughable.....why 3.2 billion years ??
..that is, 3,200, 000,000 years.....why not, 3,190, 423, 678 years....is that any more believable ??? ....what is a mere million years here and there...or even 100 million years here and there ??
If one is going to throw out wildly speculative numbers...isn't 1,000, 000 pretty speculative ??? Sheesh, we (humankind) can't even agree to as to what happened 2,000 years ago....never mind 1,000, 000 years......and that is a mere 1 million.....now we are talking billions.
It would probably be more accurate to just say " a long time ago...we think this is what could have happened" or " we surmise this could have possibly happened"...etc.
Humankind still hasn't come to grips with the origin of mankind...a mere few 1,000 years ago.....about a minuscule percentage of 3.2 billion.

Off course...when someone says" it may.....it also implies " it may NOT"...."may" just being another acronym for a wild arsed guess...

Quite frankly, I don't think mankind has even a remotest clue as to the origin of water.....earth...our universe...etc.....

Not trying to put a damper on this topic, but trying to reign in these wild arsed guesses.

Our geo friend might be able to better advise us but I vaguely recall that they do have dating techniques based on half lives and transmutation of radio active materials which give a pretty good estimation.

And like a lot of things in science they are worth doing because they are interesting. Drawing a solid inference from very limited data is a risky business though so scientists do tend to hedge this sort of proferral around with a few maybes.

[jimbunyard]

Originally Posted by MicHughV

I just find these figures to be laughable.....why 3.2 billion years ??
..that is, 3,200, 000,000 years.....why not, 3,190, 423, 678 years....is that any more believable ??? ....what is a mere million years here and there...or even 100 million years here and there ??
If one is going to throw out wildly speculative numbers...isn't 1,000, 000 pretty speculative ??? Sheesh, we (humankind) can't even agree to as to what happened 2,000 years ago....never mind 1,000, 000 years......and that is a mere 1 million.....now we are talking billions.
It would probably be more accurate to just say " a long time ago...we think this is what could have happened" or " we surmise this could have possibly happened"...etc.
Humankind still hasn't come to grips with the origin of mankind...a mere few 1,000 years ago.....about a minuscule percentage of 3.2 billion.

Off course...when someone says" it may.....it also implies " it may NOT"...."may" just being another acronym for a wild arsed guess...

Quite frankly, I don't think mankind has even a remotest clue as to the origin of water.....earth...our universe...etc.....

Not trying to put a damper on this topic, but trying to reign in these wild arsed guesses.

Bit like the 'pot calling the kettle', no?

Given what I've observed about the relative 'intelligence' within individuals of the same species, I'd say 'humankind' has been around for something on the order of a couple thousand 1000 years, at least using the metric you seem to be extolling. Credentialed anthropologists and cognitive scientists put the number, depending on certain definitions, at anywhere from 250 to 45 thousand. Perhaps you have a different, more personal definition of 'few'?...

Uncertainty and the accurate depiction of its level is one of the hallmarks of well-executed, usefully valuable science.

The hypocrisy of someone using a technology based on the success of 'wild-arsed guesses' and then lamely trying to "reign in these [same] wild arsed guesses" is, sadly, not surprising at all...

[GordMay]

In 2018, Italian scientists announced they'd discovered a body of liquid water, at the base of Mars's south polar ice cap.
The discovery was made using the MARSIS radar instrument aboard the Mars Express orbiter. The radar penetrates the Martian surface and is reflected back to the spacecraft when it encounters liquid water.
The underground lake, at the base of Mars's south pole, is about 20 kilometres wide and at least one metre thick, as that's the minimum that'd be required, for the MARSIS instrument to even detect the lake.

Any liquid water, that far underneath the planet's surface, is probably very salty, since it would be totally frozen otherwise.

“Radar evidence of subglacial liquid water on Mars” ~ by R. Orosei et al.
➥ https://science.sciencemag.org/content/361/6401/490