Visitor “placing 2 and a pair of collectively” by David Middleton
This submit is the nucleus of a speculation I’ve been making an attempt to develop. It’s a “work in progress” and never absolutely thought out or as organized as I would really like it to be. Nonetheless, I’ve gotten it to the purpose that I assumed I wanted to put in writing one thing up and submit it on WUWT to get some suggestions.
Two, Quantity One
A few years in the past, I authored a submit on “ocean deepening,” discussing this text:
Oceans are at their deepest in 250 million years
They usually have hardly been deeper within the final 400 million years than now.Lasse Biørnstad
JOURNALIST
PUBLISHED Monday 08. june 2020 – 12:24
“It strikes absurdly slowly,” says Krister Karlsen. He’s a PhD candidate in Geophysics on the College of Oslo (UiO)’s Centre for Earth Evolution and Dynamics.Karlsen is speaking about how the Earth’s tectonic plates transfer – ever so slowly however absolutely, each single yr. From a human perspective, this occurs so slowly that it’s nearly imperceptible.
[…]
The world map 200 million years in the past reveals all of the continents assembled within the supercontinent of Pangaea, a time when dinosaurs have been properly on their option to dominating the Earth’s landmasses.
Since then, the continents have been shifting farther and farther aside, and now they could be as far aside as they are often, says Karlsen. Give the Earth just a few hundred million years extra, and the continents will most likely remerge into a brand new supercontinent. One proposed identify for that attainable future reunion is Pangaea Proxima, in line with New Scientist.
The actions and age of tectonic plates have an amazing impact on the depth of the world’s oceans. Simply over 100 million years in the past, the oceans have been round 250 metres shallower on common than they’re right this moment.
The older the seabed, the deeper it’s, in line with a brand new analysis article by Karlsen and several other colleagues on the Centre for Earth’s Evolution and Dynamics.
[…]
Karlsen et al., 2020 is actually a reconstruction of plate tectonics and the age of the oceanic crust over time.
In line with their reconstruction (and others), 100 million years in the past, throughout the center of the Cretaceous Interval, the oceans have been about 250 meters shallower than they’re right this moment *and* sea degree was about 250 meters larger than it’s right this moment.
Course of that for a second… The oceans have been 250 meters shallower, however the water degree was 250 meters larger than it’s right this moment. This was because of the geometry and distribution of the ocean basins.
Throughout the Mid-Cretaceous, shallow seas coated many continental interiors…
Whereas the ocean basins have been, on common, significantly shallower than they’re right this moment.
Two, Quantity Two
There’s an attention-grabbing sample right here, the best sea ranges have occurred when the ocean basins have been at their shallowest. These have been additionally instances when atmospheric CO2 ranges and common floor temperatures have been usually elevated. The one time when circumstances have been just like the Neogene-Quaternary Durations was throughout the Late Carboniferous (Pennsylvanian) and Early Permian Durations.
This graph didn’t sit properly with the CO2-Pushed Local weather Paradigm crowd, so that they determined to “repair” the temperatures by adjusting them to pH values calculated from CO2. We are able to see that this yields a significantly better correlation between CO2 and temperature.
Oddly sufficient, the Royer/Berner temperature curve yields a decidedly non-catastrophic equilibrium local weather sensitivity of about 1.3 °C per doubling of CO2:
It’s value noting that the Royer pH-corrected temperature information point out unreasonably heat temperatures throughout Paleozoic glacial intervals.
The evaluation of Royer et al. (2004) assumes an unrealistically excessive pH correction. First, it neglects the ice-volume impact, which adjustments the relation between δ18O and ∆T. Second, this huge pH correction implies excessive temperatures for seawater even throughout instances of in depth glaciations.
Furthermore, the evaluation of Royer et al. (2004) consists of boot-strapping, by introducing a correction to ∆T that’s an implicit perform of RCO2. It’s then not shocking {that a} correlation between ∆T and RCO2 is obtained. This may be the case regardless of the RCO2 mannequin utilized.
A correct evaluation, which avoids this bootstrapping and considers a extra life like pH correction, reveals that the worldwide temperature sensitivity to CO2 remains to be comparatively small.”
Forming a speculation
Over the previous few years, I’ve been making an attempt to develop a speculation that hyperlinks the depths and normal geometries of Earth’s ocean basins to common international temperatures and atmospheric CO2. The widely accepted speculation holds that weathering charges of silicate rocks ruled the atmospheric focus of CO2 (Berner & Kothavala, 2001). That is the idea of the GEOCARB mannequin of Phanerozoic CO2.
Manner again within the Pleistocene (1976-1980), once I was a younger geology scholar, the notion of CO2 as a driver of local weather change was largely scoffed at…
Suggestion that altering carbon dioxide content material of the ambiance may very well be a significant component in local weather change dates from 1861, when it was proposed by British physicist John Tyndall.
[…]
Sadly we can’t estimate precisely adjustments of previous CO2 content material of both ambiance or oceans, neither is there any agency quantitative foundation for estimating the the magnitude of drop in carbon dioxide content material essential to set off glaciation. Furthermore the complete idea of an atmospheric greenhouse impact is controversial, for the speed of ocean-atmosphere equalization is unsure.
Dott, Robert H. & Roger L. Batten. Evolution of the Earth. McGraw-Hill, Inc. Second Version 1976. p. 441.
Someday after 1980, a brand new paradigm emerged, suggesting that Phanerozoic Eon local weather change had largely been pushed by CO2 (Royer et al., 2004). The mannequin was that the weathering charges of silicate rocks ruled the atmospheric focus of CO2 (Berner & Kothavala, 2001) and that CO2 was the “management knob” for temperature. Nonetheless, I’ve observed issues with this paradigm within the Eocene, Miocene and Pliocene Durations. It could be time for a paradigm shift.
Placing Two and Two Collectively
Assuming the Royer/Berner temperature is legitimate (a YUGE assumption), it will seem that both CO2 drives temperature or vice versa… Or one thing else drives each CO2 and temperature. I lately got here throughout a wonderful reconstruction of Phanerozoic sea degree. Chris Scotese (of PaleoMap fame) is without doubt one of the coauthors. They reconstructed the 2 major elements of sea degree change: plate tectonic eustasy (inexperienced curve) and glacial-eustasy (mild blue curve) and mixed them right into a tectono-glacio-eustasy (darkish blue curve). Unsurprisingly, sea degree adjustments over the previous 540 million years have been largely pushed by plate tectonics.
The Scotese temperature reconstruction from the Geocraft article has a fairly good match to the van der Meer sea degree reconstruction:
Whereas Berner’s GEOCARB reveals a secular decline in atmospheric CO2 over the Phanerozoic Eon, the Late Carboniferous and Neogene-Quaternary are strikingly related.
It’s necessary to notice that sea degree reconstructions are, by nature, extremely unsure. Discover how extensively the three reconstructions differ, notably throughout the Paleozoic Period.
Between temperature, CO2, sea degree and ocean depth reconstructions, there is no such thing as a lack of uncertainty. Uncertainty is pervasive in geology and climatology. Nonetheless, I’m nonetheless intent on placing two and two collectively right here.
The primary two….
Oceans are at their deepest in 250 million years
[…]The world map 200 million years in the past reveals all of the continents assembled within the supercontinent of Pangaea, a time when dinosaurs have been properly on their option to dominating the Earth’s landmasses.
Since then, the continents have been shifting farther and farther aside, and now they could be as far aside as they are often, says Karlsen. Give the Earth just a few hundred million years extra, and the continents will most likely remerge into a brand new supercontinent. One proposed identify for that attainable future reunion is Pangaea Proxima, in line with New Scientist.
The actions and age of tectonic plates have an amazing impact on the depth of the world’s oceans. Simply over 100 million years in the past, the oceans have been round 250 metres shallower on common than they’re right this moment.
The older the seabed, the deeper it’s, in line with a brand new analysis article by Karlsen and several other colleagues on the Centre for Earth’s Evolution and Dynamics.
[…]
The second two…
There’s an attention-grabbing sample right here, the best sea ranges have occurred when the ocean basins have been at their shallowest and the continents have been comparatively nearer collectively. These have been additionally instances when atmospheric CO2 ranges and common floor temperatures have been usually elevated. The one time when circumstances have been just like the Quaternary Interval was throughout the Late Carboniferous (Pennsylvanian) and Early Permian Durations.
WUWT
The humorous factor is that the best sea ranges have occurred when the ocean basins have been at their shallowest and the continents have been closest collectively.
Charges of mid-ocean ridge spreading decide the typical age of the ocean ground and due to this fact, in line with the depth/age relationship of cooling oceanic crust (Parsons and Sclater, 1977; Stein and Stein, 1992), management the amount of the ocean basins. Assuming a continuing quantity of sea-water and conservative estimates of continental hypsometry, the altering quantity of the ocean basins instantly dictates first-order imply eustatic sea degree at > 10 Myr timescales (Conrad, 2013; Miller et al., 2005; Simmons et al., 2020; van der Meer et al., 2017).
Whereas it’s an assumption, it’s an assumption based mostly on what is known concerning the geological histories of plate tectonics and sea degree variations. Tectonic eustasy strikes sea degree up and down by altering the shapes of the ocean basins. Glacial-eustasy strikes sea degree up and down by shifting water again and fourth between the oceans and continental ice sheets and glaciers. Neither course of seems to require the web addition or subtraction of seawater over the previous 540 million years. It seems that water added by volcanic outgassing and cometary impacts has been roughly balanced by the water subducted into the decrease crust and mantle. Glacial-eustasy has hardly ever been a major issue throughout the Phanerozoic Eon.
The deeper the oceans, the extra CO2 they will retailer. In line with my Stratigraphy & Sedimentation textbook, Ideas of Sedimentology by Friedman and Sanders…
When the pH of seawater decreases, calcium carbonate dissolves. In heat, shallow seas, at a pH of about 8.3, dissolution of aragonite and calcite particles by inorganic processes is nearly nonexistent. Nonetheless, because the classical research of the Challenger expedition, it has been identified that the proportion of calcium-carbonate particles in seafloor sediments decreases as depth of water will increase (Desk 5-1). Such lower is especially fast at depths between 4000 and 6000 m. Though the explanations for this lower have been debated, the proof means that calcium carbonate dissolves as a result of the CO2 focus will increase with depth. The management on CO2 seems to be half organic; it outcomes from organic oxidation of organic-carbon compounds. Additionally, the water lots at larger depth have been derived from the polar area; their temperature is decrease and the water accommodates extra dissolved CO2. Elevated focus of CO2 is in flip mirrored by decrease pH, which results in calcium carbonate dissolution. Nonetheless, the rise of stress with depth might also be concerned; such improve impacts the dissociation of carbonic acid (Eqs. 5-11 and 5-12). The depth at which the calcium-carbonate decreases most quickly is called the carbonate-compensation depth, outlined because the depth at which the speed of dissolution of stable calcium carbonate equals the speed of provide.
Friedman and Sanders
A really thorough, straightforward to learn, description of the connection between CO2 and seawater pH… Nonetheless, the phrase “ocean acidification” is notably absent from the complete 300+ pages. How is that this attainable?
Even means again then, we knew that previous atmospheric CO2 concentrations have been usually a lot larger and the oceans had oscillated between calcitic and aragonitic seas in periods of excessive and low atmospheric CO2 concentrations. The graph under is kind of a cartoon; but it surely demonstrates that throughout the Phanerozoic Eon, the one two intervals when magnesium-enriched calcite and, much less abundantly aragonite, dominated marine geochemistry have been from the Mid-Carboniferous to the Late Triassic Durations and the Neogene to Quaternary Durations (~35 MYA to right this moment).
These two time intervals additionally featured deeper ocean basins, ice sheets over one or each polar areas, comparatively intensive alpine & valley glaciation, low concentrations of atmospheric CO2 and customarily cool to chilly weather conditions.
The CO2 storage capability of deep oceans (3,000m water depth) is very large. It us so huge that some have recommended injecting it on the seafloor in deepwater.
CAPACITY
Oceans occupy greater than 70% of the Earth’s floor and have a median depth of about 3.8 km. Contemplating the saturation focus of CO2 in seawater, this storage capability is orders of magnitude larger than the capability wanted to soak up the CO2 produced by burning the entire world’s fossil gasoline assets, equal to an estimated 5000 to 10,000 GtC.
Now, I’m not advocating doing this. It will be prohibitively costly and more likely to trigger precise environmental hurt. I’m simply noting that the inventor of the phrase, “ocean acidification,” thinks that is value wanting into.
The oceans know what to do with CO2:
CO2 exists in seawater in varied varieties as a part of the carbonate system:
The relative proportions of those species are outlined by the pH of the answer and by equilibrium relationships. Dissolving extra CO2 will increase manufacturing of hydrogen ions (lowering pH), however the change is buffered by conversion of carbonate into bicarbonate. Thus, the principal reactions for CO2 dissolution in seawater are as follows:
The CO2 that has collected within the shallower waters of the oceans will finally discover its option to deeper waters anyway by way of the organic carbon pump. It would simply take for much longer than capturing it and injecting it.
I feel that adjustments within the depths of the ocean basins, over geologic time, has moved the carbonate compensation depth (CCD) up and down and that that is Earth’s major management knob for atmospheric CO2. Durations with shallower ocean basins have usually had shallower CCD’s, larger concentrations of atmospheric CO2 and customarily hotter temperatures. I feel adjustments within the depths of the ocean basins can largely clarify these items. Whereas there clearly is a few relationship between CO2 and temperature, I don’t suppose it’s the dominant think about both route over geologic time. I don’t think about the ~100,000 yr Late Pleistocene glacial cycles, when temperature adjustments clearly drove adjustments in atmospheric CO2, to be geologic time. These short-term fluctuations aren’t resolved over 10’s of hundreds of thousands of years. Nor do I think about adjustments over the previous 150 years to be geologic time. That is actually “noise.” This speculation I’m making an attempt to develop, will attempt to clarify adjustments over hundreds of thousands to tens of hundreds of thousands of years.
Any solutions as to find out how to proceed could be useful In fact, if the speculation has so little advantage, that I shouldn’t waste any extra time on it, please let me know.
Now I simply must work out the small print… Keep tuned for extra posts on this matter.
References
Adams, EE, Caldeira, Okay, 2008. Ocean Storage Of CO2, Components 4 (5):319-324, DOI: 10.2113/gselements.4.5.319.
Berner, R.A. and Z. Kothavala, 2001. “GEOCARB III: A Revised Mannequin of Atmospheric CO2 over Phanerozoic Time”, American Journal of Science, v.301, pp.182-204, February 2001.
Dott, Robert H. & Roger L. Batten. Evolution of the Earth. McGraw-Hill, Inc. Second Version 1976. p. 441.
Friedman, G.M. and Sanders, J.E. (1978) “Ideas of Sedimentology”. Wiley, New York.
Goswami, A.; Hinnov, L.; Gnanadesikan, A.; Younger, T. Sensible Paleobathymetry of the Cenomanian–Turonian (94 Ma) Boundary World Ocean. Geosciences 2018, 8, 21.
Karlsen, Krister S., Mathew Domeier, Carmen Gaina, Clinton P. Conrad,
A tracer-based algorithm for automated technology of seafloor age grids from plate tectonic reconstructions, Computer systems & Geosciences, Quantity 140, 2020, 104508, ISSN 0098-3004, https://doi.org/10.1016/j.cageo.2020.104508.
Royer, D. L., R. A. Berner, I. P. Montanez, N. J. Tabor and D. J. Beerling. “CO2 as a major driver of Phanerozoic local weather”. GSA As we speak, Vol. 14, No. 3. (2004), pp. 4-10
van der Meer, Douwe G., Christopher R. Scotese, Benjamin J.W. Mills, Appy Sluijs, Aart-Peter van den Berg van Saparoea, Ruben M.B. van de Weg. Lengthy-term Phanerozoic international imply sea degree: Insights from strontium isotope variations and estimates of continental glaciation. Gondwana Analysis, Quantity 111, 2022, Pages 103-121, ISSN 1342-937X, https://doi.org/10.1016/j.gr.2022.07.014.
