# Is the planet Earth losing water? **URL:** \ **Category:** Factual Questions\ **Created:** [January 12, 2020, 12:39pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305 "2020-01-12T12:39:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [January 12, 2020, 12:39pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/1 "2020-01-12T12:39:08Z")
I was thinking about Mars and how it lost its water, and that, for obvious reasons, made me think about Earth. Now Earth has an advantage over Mars due to the larger gravity and the still molten and spinning iron core. But… a lot of the same processes still have to be at work. Water is pretty volatile, that’s kinda what “humid” means. Hell, that’s why we have clouds. Now, you get some of those water molecules really high up and they are likely to break due to solar radiation. Hydrogen spins off into space, no more water molecule. Now, I don’t think this is something we need to be worried about, but as an intellectual exercise, how much is lost? It may not be much, but it’s got to be non zero, right? Follow up, is there enough incoming water from icy meteorites to offset this? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 12, 2020, 12:55pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/2 "2020-01-12T12:55:00Z")
[Subduction](https://www.newscientist.com/article/mg16322030-200-leaky-seas/) [is likely](https://www.earthmagazine.org/article/thirsty-mantle-subduction-zones-swallow-more-water-thought) the bigger “worry.” ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [January 12, 2020, 1:29pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/3 "2020-01-12T13:29:54Z")
Subducted water could come back out again, if the rate of outgassing increased for some reason. Water has been going in and out of the crust and mantle for billions of years The long-term problem is water loss at the top of the atmosphere. This link suggests we’ve got about a billion years until the Sun heats up enough to boil the oceans; a bit more optimistic than other recent estimates I’ve read. > **[When will Earth lose its oceans?](https://www.sciencedaily.com/releases/2013/12/131216142310.htm)** > > The natural increase in solar luminosity -- a very slow process unrelated to current climate warming -- will cause the Earth's temperatures to rise over the next few hundred million years. This will result in the complete evaporation of the oceans.... A billion years doesn’t really cause me much existential angst. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [January 12, 2020, 1:39pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/4 "2020-01-12T13:39:38Z")
Yep, I think the worry is the opposite - that the lack of water could slow down or stop tectonic movements, because water below the crust encourages vulcanism and thus the churning of the mantle. Which would lead to the rest of the water (and carbon, etc.) in the earth being locked up. ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [January 12, 2020, 2:02pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/5 "2020-01-12T14:02:47Z")
Well, the is this: [link](https://sciencenordic.com/chemistry-climate-denmark/the-earth-has-lost-a-quarter-of-its-water/1462713) > [@](#): > > “By examining how the ratio of these isotopes has changed, we have been able to determine that over the course of around four billion years, the Earth’s oceans have lost about a quarter of their original mass." ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 12, 2020, 4:40pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/6 "2020-01-12T16:40:55Z")
Good link **armedmonkey**. In the other direction is _new water_ being created and added to the hydrological cycle by the burning of fossil fuels. (This is very different than the water consumption of fuel production which while removed from lakes and aquifers is still within the hydrological cycle, mostly used up as evaporative losses and into vapor, and in recent years some relatively sequestered injected deep during fracturing and deep well drilling.) To think of it pretty simplistically the oxidation of fossil fuel produces both new CO2 and new water from the hydrocarbon and oxygen: CH4[g] + 2 O2[g] -\> CO2[g] + 2 H2O[g] + energy. Given that we know we are adding significant amounts of CO2 by the process, it follows that we are also adding water as well. (It just isn’t where we want it.) Real world fuel is of course not all methane and has variable amounts of sulfur and nitrogen but [academics have done the math](https://iopscience.iop.org/article/10.1088/1748-9326/aa8390/pdf) for us: > [@](#): > > … The annual global formation of water from combustion of hydrocarbon fuels from 2005–2015 amounted to an average of 1.2 × 10[sup]13[/sup] kg⋅yr[sup]−1[/sup] … \ …This work finds that the total annual quantity of water formed from combustion of hydrocarbon fuels exceeds the water sequestered from the hydrologic cycle through deep well injection in the US … The subduction calculations are highly limited not only by the fact noted in the article, that how much water is released by volcanic activity is not very well understood, but also by the fact that vulcanism (and its associated release of sequestered water) may not be a consistent item over geological epochs. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 12, 2020, 5:05pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/7 "2020-01-12T17:05:03Z")
Also **armedmonkey** you should likely also highlight that your linked article suggests almost all of that loss was early in the earth’s history, slowed down dramatically since the atmosphere increased its oxygen concentration. > [@](#): > > "Hydrogen and deuterium are still escaping into space, but very slowly, says Pope. > > “Today the atmosphere is rich in oxygen, which reacts with both hydrogen and deuterium to recreate water, which falls back to the Earth’s surface. So the vast bulk of the water on Earth is held in a closed system that prevents the planet from gradually drying out." ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [January 12, 2020, 5:43pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/8 "2020-01-12T17:43:01Z")
Thank you **DSeid** , but, and don’t take this the wrong way, I am well aware of how combustion works. I don’t need the methane stoichiometry. I also know that my link was to a an article that summarizes an only sorta peer reviewed study by some Danish scientists regarding stuff that happened a long, long time ago. But the question still holds. The Earth’s atmosphere just _has_ to be outgassing, at least a little. Simple gravity and the magnetosphere keeps the vast majority of it in, but it can’t stop the “solar wind” completely, can it? I mean, some of it has to be stripped off, right? ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [January 12, 2020, 6:07pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/9 "2020-01-12T18:07:48Z")
Hey, I found [this](https://phys.org/news/2016-07-curious-case-earth-leaking-atmosphere.html) This leads me to believe, which seems obvious in retrospect, that we are losing water vapor at roughly the same rate as everything else. But… and it’s a fine point, but this is a thread about negligible but non-zero loss, I wonder if the loss of water is faster than that of say, Nitrogen. H2O is just an ionic bond - it doesn’t take a whole lot of energy to split that thing. And Hydrogen is very light, it should be the stuff more able to be stripped off by all those fast moving alpha particles from the sun. I think. But I don’t really know. That’s why I posted this. 🙂 ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 12, 2020, 6:55pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/10 "2020-01-12T18:55:30Z")
Not sure what you are defensive about. My comment was merely how changes of the Anthropocene are huge and fast compared to other periods of our history. Anyway the actual meat of your most recent citation is interesting. First it answers that yes hydrogen leaves the atmosphere preferentially. > [@](#): > > Singling out just cold ions (light hydrogen ions, which require less energy to escape and thus possess a lower energy in the magnetosphere), the escape mass totals thousands of tonnes per year. But it isn’t completely stripped away. Lots apparently comes back. > [@](#): > > These ions are shunted onto different drift trajectories, gain energy, and end up heading away from Earth into the magnetotail, where they interact with plasma and return to Earth at far higher speeds than they departed with – a kind of boomerang effect. Meanwhile I found [this](http://faculty.washington.edu/dcatling/Catling2009_SciAm.pdf). > [@](#): > > … The loss rate is currently tiny, only about > three kilograms of hydrogen and 50 grams of helium (the two lightest gases) per second … > \ > …Today hydrogen escape is limited to a trickle because the > principal hydrogen-bearing gas, water vapor, > condenses in the lower atmosphere and rains > back to the surface. But our sun is slowly brightening at about 10 percent every billion years. > That is imperceptibly slow on a human timescale > but will be devastating over geologic time. As the > sun brightens and our atmosphere warms, the > atmosphere will get wetter, and the trickle of hydrogen escape will become a torrent. > This process is expected to become important > when the sun is 10 percent brighter—that is, in a > billion years—and it will take another billion > years or so to desiccate our planet’s oceans. It also explains the exact mechanisms. ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [January 12, 2020, 7:52pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/11 "2020-01-12T19:52:54Z")
I wasn’t defensive, you just weren’t really on topic. But now you are! Thanks! ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 12, 2020, 8:57pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/12 "2020-01-12T20:57:45Z")
Water is also created in the upper atmosphere through interaction with oxygen molecules and the ionized hydrogen in the solar wind. The same process creates water on the moon as well, and may even be the source of most of the ice in the polar craters. ---
**Author:** ![RioRico](https://avatars.discourse-cdn.com/v4/letter/r/f04885/32.png) [@RioRico](https://boards.straightdope.com/u/RioRico)\ **Post date:** [January 12, 2020, 9:08pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/13 "2020-01-12T21:08:14Z")
> [@eburacum45](#): > > A billion years doesn’t really cause me much existential angst. A lecturing cosmologist proclaimed that Sol will go nova in 4 billion years, destroying Earth. A man rose in the audience and yelled, “What?!? How long do we have?” The lecturer repeated, “Four billion years.” The audience member sighed with relief. “Oh, BILLION! I though you said MILLION! Whew!” If humanity hasn’t left Terra and conquered the universe by then, we deserve extinction. Meanwhile, to stem H2 and H2O loss, merely slam small icy comets into the Pacific. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [January 12, 2020, 10:27pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/14 "2020-01-12T22:27:06Z")
And do it during the evening so it will also kick us slightly outward at the same time. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [January 12, 2020, 10:33pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/15 "2020-01-12T22:33:03Z")
Water loss (actually hydrogen loss) will continue at a slowly increasing rate for the next billion years, and during this time we could lose another small but significant fraction of our water. Ten, twenty percent over a gigayear? We will still have deep oceans at this point, however. But at around a billion years from now the oceans at the equator will start to boil, and this will release vast amounts of water vapour into the atmosphere- water vapour is a greenhouse gas, so the temperature of the Earth will skyrocket, and we’ll lose most of our hydrogen and become like Venus. We might be lucky and retain some deuterium, though. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 12, 2020, 11:35pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/16 "2020-01-12T23:35:20Z")
> [@armedmonkey](#): > > I wasn’t defensive, you just weren’t really on topic. But now you are! Thanks! The second part of your question was if enough new water was coming in to offset the losses (you specifically asking about icy meteorites). Annually the amount of new water coming into the system from the burning of fossil fuels more than offsets the losses, by, if I calculated at all near correctly, three to four _orders of magnitude_. Icy meteorites need not apply. ---
**Author:** ![Arcite](https://avatars.discourse-cdn.com/v4/letter/a/67e7ee/32.png) [@Arcite](https://boards.straightdope.com/u/Arcite)\ **Post date:** [January 12, 2020, 11:53pm UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/17 "2020-01-12T23:53:13Z")
According to the Wikipedia article on the [Future of the Earth](https://en.wikipedia.org/wiki/Future_of_Earth): > [@](#): > > The luminosity of the Sun will steadily increase, resulting in a rise in the solar radiation reaching the Earth. This will result in a higher rate of weathering of silicate minerals, which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees. Some plants use the C4 carbon fixation method, allowing them to persist at carbon dioxide concentrations as low as 10 parts per million. However, the long-term trend is for plant life to die off altogether. The extinction of plants will be the demise of almost all animal life, since plants are the base of the food chain on Earth. So if this is correct, never mind a billion years; 400 million years sooner than that, life as we know it on earth will die out. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [January 13, 2020, 12:13am UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/18 "2020-01-13T00:13:21Z")
Indeed. That was not the question in the OP, however. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 13, 2020, 12:32am UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/19 "2020-01-13T00:32:30Z")
> [@RioRico](#): > > A lecturing cosmologist proclaimed that Sol will go nova in 4 billion years, destroying Earth. A man rose in the audience and yelled, “What?!? How long do we have?” The lecturer repeated, “Four billion years.” The audience member sighed with relief. “Oh, BILLION! I though you said MILLION! Whew!” Yes, I’m betting that most of us here watched _Cosmos_. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [January 13, 2020, 9:10am UTC](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305/20 "2020-01-13T09:10:01Z")
> [@DSeid](#): > > The second part of your question was if enough new water was coming in to offset the losses (you specifically asking about icy meteorites). Annually the amount of new water coming into the system from the burning of fossil fuels more than offsets the losses, by, if I calculated at all near correctly, three to four _orders of magnitude_. Icy meteorites need not apply. It is a shame we only have a limited amount of fossil fuel to burn, in that case. The hydrogen in the hydrocarbons is the important factor; when we run out of hydrocarbons to burn, there won’t be any new hydrogen entering the hydrosphere from that source any more, and we’ll still be losing hydrogen at the top of the atmosphere at a rate of 95,000 tonnes per year. > **[Who, What, Why: Is the Earth getting lighter?](https://www.bbc.co.uk/news/magazine-16787636)** > > The BBC's Radio 4 programme More or Less was asked by one of its listeners if planet Earth's weight is increasing or falling. [Next page](https://boards.straightdope.com/t/is-the-planet-earth-losing-water/846305.md?page=2)