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NNadir

(33,368 posts)
Sat Aug 29, 2020, 08:09 AM Aug 2020

Sources of Water Contributing to Sea Level Rise Since 1900.

The paper I'll discuss in this post is this one: The causes of sea-level rise since 1900 (Frederikse et al., Nature 584, 393–397 (2020))

Most of the time, I incorporate the title of papers I discuss in this space - to the extent possible - in the title of the post, but as it happens, this paper would be better titled as I have done. The main cause of sea level rise is climate change; followed by the removal of fossil ground water for irrigation and ultimately evaporation and transpiration.

The latter cause, the unsustainable mining of fossil ground water for agriculture, as I learned in this lecture a while back, contributes significant amounts of water to the rise in sea level: During the lecture, Dr. Robert Kopp, the speaker, estimated about 10% of sea level rise was attributable to mined ground water, if I recall correctly. Examples of places where fossil ground water is mined in vast amounts are the Ogalalla aquifer underlying significant portions of the American Midwest, and the California aquifer underlying the San Joaquin Valley. Both aquifers are being rapidly depleted and without a source of water, as agricultural zones they will die.

Thinking about all of this has lead me to have elaborate geoengineering fantasies - they are just that, fantasies - involving supercritical water desalination of the surface waters of the very dirty inland sea, the Gulf of Mexico, a process that would involve supercritical water oxidation of microplastics increasingly found there, persistent organic pollutants, oil residues from the far from ameliorated Deepwater Horizon data that went down the memory hole even while the earlier event at Fukushima which in many ways was less odious, didn't, as well as the recovery of carbon dioxide - most of this dumped dangerous fossil fuel waste is in the oceans where it acidifies it, - as well as valuable minerals like calcium, magnesium, uranium, and perhaps copper and zinc, and perhaps most importantly, the phosphorous (and more carbon dioxide) resulting eutrophication generating biomass caused by runoff into the Mississippi from Iowa and neighboring states as part of the so called "renewable energy" disaster represented by ethanol production for motor fuels.

In my fantasy, the water from this process is steam driven to central North America to restore and refill the Ogalalla and other depleted mined waters, Owens Lake, the California aquifer and the dead Colorado River delta. It's a nice fantasy, but it's just that a fantasy. While remotely feasible, I think, it is clear that humanity is far too stupid to embrace such an idea because of the source of energy such a scheme would require. Humanity would rather believe that so called "renewable energy" will save the world. It hasn't saved the world; it isn't saving the world; and it won't save the world, but as we are seeing, to some amazement, the early 21st century is a period in history where the embrace of lies has subsumed and battered the truth.

Happily, truth is not a function of belief, and it will, as it must, because it is truth, reemerge in smarter times.

As for fantasies, sometimes one realizes something like them, but most often not. Meeting someone like my wife was a fantasy I had as a young man, but in many ways she is different, indeed better, than the fantasies. Reality doesn't always suck, but sometimes it does. Acting on fantasies however can also go very badly: Many popular energy fantasies from the last quarter of the 20th century have caused more harm than good. Things are getting worse because of our reliance on the so called "renewable energy" fantasy. Whether reality of draining a little of the ocean by supercritical water desalination would prove to be as good as the fantasy of doing so, will almost certainly never be known.

Anyway...

The paper refines Dr. Kopp's estimation that I remember from Dr. Kopp's wonderful lecture.

I will not see the like again.

(The death of science lectures as a result of Trump's incompetence and lies about Covid-19, is yet another tragedy, perhaps a relatively minor one, among the thousands, that the normalization of his lies and acceptance of his ignorance and corruption has caused. No matter how great a President Joe Biden proves to be; it will be a very long time before we're past this damage, generations probably, caused by this nearly missed triumph of stupidity and racism.)

Anyway...

Anyway...

The abstract, available from the link to the paper above, is worth reading. From the paper's introduction:

Main
Global-mean sea level (GMSL) has increased by approximately 1.5 mm yr^(?1) (refs. 1,4,5) over the twentieth century, modulated by large multidecadal fluctuations6. Changes in GMSL are the net result of many individual geophysical and climatological processes, with some of the largest contributions coming from ice-mass loss and thermal expansion of the ocean. The level of agreement between the sum of these individual contributions and the observed changes in GMSL—often described as the ‘sea-level budget’—is a key indicator of our understanding of the drivers of sea-level rise7. Multiple studies show closure of the sea-level budget within their stated uncertainties since the 1960s and over the era of satellite altimetry since 19938,9,10. However, rates of GMSL change and their contributions to the budget over the entire twentieth century, and especially the first half of the twentieth century, have not yet been fully explained or attributed. Previous observation-based studies concluded that the GMSL budget for the whole twentieth century could not be closed within the estimated uncertainties2,3. Various explanations for this non-closure have been proposed, including an overestimation of the tide-gauge-derived rates of GMSL change11 and underestimation of the ice-sheet contribution12, but there is no agreement yet on the cause of this discrepancy13.

Over the past few years, revised estimates of the main known driving processes of global sea-level rise that cover the entire twentieth century have become available14,15,16,17, the spread among different estimates of twentieth-century glacier mass loss has been reduced18, and improved mapping methods and correction of instrumental bias have resulted in higher estimates of the contribution from thermal expansion since the 1960s19. In parallel, estimates of twentieth-century GMSL change have converged to lower rates than previously estimated, as a result of improved reconstruction approaches, spatial-bias correction schemes, and the inclusion of estimates of local vertical land motion (VLM) at tide-gauge locations4,9,20. As a result of these developments, the GMSL budget needs to be re-estimated, to determine whether the observed sea-level rise since 1900 can be reconciled with the estimated sum of contributing processes...

...To obtain estimates of changes in global ocean mass (barystatic changes), we combine estimates of mass change for glaciers16,21, ice sheets14,22,23,24,25 and terrestrial water storage (TWS). For the TWS estimate, we consider the effects of natural TWS variability17, water impoundment in artificial reservoirs26 and groundwater depletion27,28. For 2003–2018, we use observations from the Gravity Recovery and Climate Experiment (GRACE)29 to quantify the barystatic changes. We estimate changes in sea level due to global thermal expansion (thermosteric changes) from in situ subsurface observations30,31,32 over the period 1957–2018, and combine these estimates with an existing thermosteric reconstruction15. To obtain an estimate of GMSL changes and their accompanying uncertainties, we combine tide-gauge observations with estimates of local VLM from permanent Global Navigation Satellites System (GNSS) stations and with the difference between tide-gauge and satellite-altimetry observations.


The authors note that many traditional methods of measuring sea level, notably tide gauges, are subject to significant variability:

Each tide-gauge and VLM record is affected by glacial isostatic adjustment (GIA) and by the effects of gravity, rotation and deformation (GRD) from contemporary surface-mass redistribution due to changes in ice mass and TWS


VLM here is "vertical land motion" and TWS is "terrestrial water storage" - for example, dams. The authors note that another so called "renewable energy" disaster affecting sea levels - in this case it slowed sea level rise - was the widespread enthusiasm for the construction of these dams, which they state peaked in the 1970's.

Graphics from the text:



The caption:

a, Observed GMSL, and the estimated barystatic and thermosteric contributions and their sum. b, The barystatic contribution and its individual components. The TWS term is the sum of groundwater depletion, water impoundment in artificial reservoirs and the natural TWS term. c, 30-year-average rates of observed GMSL change and of GMSL change as a result of the different contributing processes. d, 30-year-average rates of GMSL change due to the barystatic contribution and its individual components. The shaded regions denote 90% confidence intervals. The values in a and b are relative to the 2002–2018 mean.


GMSL = Global Mean Sea Level. The word barystatic refers to mass transfer, that is ice to seawater, groundwater to seawater, etc. The "static" root of the word is misleading.



The caption:

Figure 2
a, Fraction with all components included. b, Fraction after omitting the TWS component. The shaded regions denote 90% confidence intervals.





The caption:

Figure 3

a–f, Observed basin-mean sea level, and the estimated contributions and their sum, for the different basins (as indicated on the map). Contrary to the global case, GIA causes basin-mean changes in sea level, and so is included in the sum of contributors. The shaded regions denote the 90% confidence interval. The values are relative to the 2002–2018 mean.


There's quite a bit of interesting detail in the discussions of the full paper's text. It's worth reading if one can access it. I do hope to find some time to spend with it.

From the authors' conclusions:

We reconstructed the GMSL since 1900 and compared it to the sum of the contributing processes. We found that these processes explain the observed twentieth-century GMSL trend and match the multidecadal variability pattern, except for the low rates in observed sea-level rise during the 1920s. Barystatic changes are the primary contributor to sea-level rise, with glacier mass loss being the largest component. Reservoir impoundment caused a substantial, albeit temporary, slowdown of GMSL rise during the 1970s. The relative contributions of thermosteric and barystatic changes to GMSL vary with time. On basin scales, trends and multidecadal variability deviate from the global mean, mostly as a result of variability in the steric component...

...Closure of the twentieth-century sea-level budget, as demonstrated here, implies that no additional unknown processes, such as large-scale deep-ocean thermal expansion or additional mass loss from the Antarctic Ice Sheet, are required to explain the observed changes in global sea level. Such additional processes had been speculated to explain the non-closure found in previous studies of global sea-level budget2,3,12. Our demonstration of closure of the global-mean and basin-mean sea-level budget forms a consistent baseline against which process-based and semi-empirical sea-level projections can be benchmarked, without the need to compare against either the sum of processes or observed sea level37. The downward revision of the estimated sea-level rise and updated estimates of the driving processes, particularly the increased estimated glacier mass loss, result in a consistent picture of twentieth-century GMSL rise and its underlying causes.


Cool paper, I think.

I hope you will have as safe and as enjoyable weekend as is possible in these dire times.

5 replies = new reply since forum marked as read
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Sources of Water Contributing to Sea Level Rise Since 1900. (Original Post) NNadir Aug 2020 OP
I like your fantasy plan. Laelth Aug 2020 #1
Any attempt to raise seawater to a supercritical state - other than the place it occurs naturally... NNadir Aug 2020 #2
Hear! Hear! Laelth Aug 2020 #3
That TEOS-10 site is a wonderful resource. hunter Aug 2020 #4
Yes, that's the basic idea. There are actually two types of salts... NNadir Aug 2020 #5

Laelth

(32,017 posts)
1. I like your fantasy plan.
Sat Aug 29, 2020, 09:04 AM
Aug 2020

We could obviously use the byproducts of desalination. Also, obviously, it would require nuclear power to run the desalination plants and to move the water back into the aquifers. Why not?

-Laelth

NNadir

(33,368 posts)
2. Any attempt to raise seawater to a supercritical state - other than the place it occurs naturally...
Sat Aug 29, 2020, 09:53 AM
Aug 2020

... which is in hydrothermal vents - that does not use nuclear power, will be unsustainable.

Nuclear power is the only source of energy that has the energy/mass ratio capable of cleaning up huge environmental damaged regions.

It is, in fact, the only source of energy capable of cleaning the atmosphere.

In connection with this fantasy I have given some thought to mucking around in TEOS-10 to actually determine the amount of energy it would require to desalinate hundreds of cubic km of seawater by raising it to a supercritical state (although last I looked, the equation of state for seawater was poorly defined at very high temperatures), but clearly the amount of energy would be prodigious. However, a significant portion of that energy could in theory be recovered as expansion and process enthalpy. I suspect the separations would be cleaner if the supercritical temperatures were actually higher than the melting point of sodium chloride.

Having the time to muck around in TEOS-10, and worse, trying to fill in the blanks, is, of course, another fantasy.

Sigh...there is so much to learn...and so little time. Tears in the rain...

Life is interesting and then you die.

Laelth

(32,017 posts)
3. Hear! Hear!
Sat Aug 29, 2020, 10:01 AM
Aug 2020

Absent some change in the laws of physics, humans, if we don’t go extinct first, will have to rely on nuclear power.

Thanks for the thoughtful reply.

-Laelth

hunter

(38,264 posts)
4. That TEOS-10 site is a wonderful resource.
Sun Aug 30, 2020, 04:31 PM
Aug 2020

It reminds me of an undergraduate term paper I wrote on ocean water chemistry back when people were first sampling hot water plumes from the Galapagos Hot Spot. I got to talk to some of the people who were doing it, which is what enthusiastic students did before the World Wide Web. Library research could be slow.

In your desalinization scheme would it be possible to simply "drain off" the molten sodium chloride in a continuous process?

Carbon dioxide removed from the ocean is, of course, as good as removing it from the atmosphere. If seawater is being pulled out of the ocean to have the salt removed one may as well grab the carbon dioxide and sequester it in some fashion.

NNadir

(33,368 posts)
5. Yes, that's the basic idea. There are actually two types of salts...
Sun Aug 30, 2020, 05:56 PM
Aug 2020

...that precipitate in supercritical water. Type one salts are the common halides, NaCl, KCl, nitrates and phosphates, presumably bromides as well.

Type 2 salts include sodium sulfate, sodium carbon carbonate and other compounds.

Type 1 forms a separate, fluid phase, from the supercritical water, in which they are insoluble.

Sulfates and carbonates by contrast, in may SCW systems form solids. The extent to which these solids are soluble in a molten salt/water phase is not clear to me; presumably the carbonates would decompose to oxides at high enough temperatures, which, given the acidity of SCW, is a good thing.

This knowledge derives from the situation with waste water, in which SCW oxidation (SCWO) is the stated goal. (A lot's been written about this.) It's not quite seawater though.

On the other hand, the Gulf of Mexico has been treated like a sewer in many ways.

Lipids, oils, petroleum residues presumably cracked polymers and depolymerized polymers, presumably are extracted into the SCW, and at high enough temperatures, reformed into carbon dioxide and hydrogen, largely.

This might have a happy effect on the well trashed Gulf of Mexico waters.

I do believe that the phase diagram of this system might prove to be fairly complex; the phase into which gases are extracted is unclear. If I recall correctly, SCW and SCCO2 are separate phases.

There is a commercially available viscometer, the Anton Paar 302, that can be modified to determine the viscosity (and other parameters related to fluid structure) of molten sea salt. I don't know that anyone has done this; I haven't really looked though.

I'm primarily interested in the fate of phosphate, and it would be interesting to know how phosphate salts behave in molten salts, or the superfluid type one salt system.

It is quite possible to do some solid phase extraction of some elements and compounds, depending on the desire to recover them or avoid undesirable effects downstream.

Other than the soluble hydrophobic organics in supercritical water, it should be fairly clean; and again, at higher temperatures, they should reform into carbon monoxide/dioxide/hydrogen. By releasing pressure, this system conceivably could yield very pure steam to be utilized for any number of purposes.

It's an interesting idea. All that's needed is clean energy and of course, refractory corrosion resistant materials. Mostly it's a materials science problem.

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