by Chris Hall
Introduction
This article builds on a previous posting of mine entitled “Sea Level Rise: Hockey Stick or Roller Coaster”. See:
In that article, I outlined an approach that I used to tease out signs of acceleration in the rate of rise of sea level in the historical tidal gauge provided by the Permanent Service for Mean Sea Level or PMSL (Holgate et al., 2013; PSMSL, 2022). The posting was inspired by the peer reviewed article Nerem et al. (2018), herein referred to as PNAS2018. In that article, the authors estimated the current rate of change of the rate of sea level rise (i.e., sea level acceleration) and they argued that the historical tidal gauge record was inadequate for measuring sea level acceleration of the past. I wanted to see what the tidal gauge record had to say about historical sea level rise acceleration.
Briefly, I explored many different avenues to calculate prior sea level rise acceleration to see if I could determine whether modern acceleration found in PNAS2018 was a novel and new phenomenon, or whether this sort of acceleration ebbed and flowed throughout the 20th century. I wound up picking a subset of data from the most complete tidal gauge records over the period from 1925 to 2015, a kind of top 100 sites on the “Tidal Gauge Hit Parade”. Using that subset, the best method that I found to combine acceleration signals, in a manner that did not produce artifacts caused by missing data points, was to first calculate an acceleration record for each site and then combine the acceleration data using an area-weighted average. See the previous post for details on the method used.
Since posting that article of WUWT, I realized that I could use a similar technique to cast a wider net and exploit data from a much larger subset of the 1548 sites recorded in the PMSL dataset. The results of that effort are outlined in this posting and it represents the maximal amount of historical sea level acceleration information that I can derive.
Where The Data Are
The PMSL dataset that I had downloaded had site information for a total of 1548 tidal gauge sites, but only 1537 sites had local sea level data. Records begin in 1807 for the tide gauge in Brest, France, and the information that I had finished at the end of 2021.
To get a measure of sea level rise acceleration, ideally I would use 25 years (plus 1 month) of data centered about a point in time and I fitted a quadratic polynomial to the data. Because of missing data, the raw information can resemble Swiss cheese at times, so I relaxed the rules a bit so that I required that, for a given month at a site, there had to be a minimum of 200 valid data points within the plus or minus 12.5 year time window surrounding that month. The choice of 200 as a cutoff was arbitrary, but reasonable given that it meant that there were sufficient data points to get some decent fitting statistics and that both the time preceding and after the chosen month are represented.
In Fig. 1, I show the number of sites that could contribute acceleration data points to the overall record as a function of time. Note the logarithmic scale. There are very few usable sites in the first part of the 19th century, but after about 1880, things pick up a bit. By about 1920, the density of available date becomes much more substantial.
I also would like to express a mea culpa about my earlier article. I had neglected to calculate error estimates for the sea level acceleration values, which is a bit embarrassing for me given that the late great Derek York was my PhD supervisor. Derek was the man who taught isotope geochemists how to properly fit straight lines through arrays of isotope ratio data points, and before you scoff at that and say it’s trivial, in fact it is a tricky bit of nonlinear inverse theory. So as penance, I have endeavored to provide error estimates for acceleration values in this article.
But first, I want to address an issue raised in the comments from my previous article. It deals with the issue raised that it is important to look at the details of each site’s local conditions and that such factors can significantly affect the apparent sea level rise acceleration. In the next section, I look at this question, which to a certain extent hinges on the philosophical distinction in scientific communities between “lumpers” and “splitters”. I was trained as an engineer and worked in both physics and geology departments. Physicists tend to be “lumpers”, i.e., they are delighted if they can mostly explain a phenomenon. “Splitters” delight in examining all of the exquisite details and are never happy until all of the different details of a phenomenon are categorized. Geologists tend to be splitters. Because I am fundamentally a lazy person, I tend to fall into the lumper category, and I confess my sins happily.
The Acceleration Record is Mostly Global, Mostly
It was argued that local effects like the pumping of groundwater might cause an increase of local sea level rise. My original take was that this was an anthropological effect that should show up as positive, recent acceleration. However, it was also noted that if pumping stopped, that this could show up as a deceleration and be misconstrued as being a natural phenomenon. I decided to do a little test of this hypothesis and the results are shown in Fig. 2.
It was argued that local effects like the pumping of groundwater might cause an increase of local sea level rise. My original take was that this was an anthropological effect that should show up as positive, recent acceleration. However, it was also noted that if pumping stopped, that this could show up as a deceleration and be misconstrued as being a natural phenomenon. I decided to do a little test of this hypothesis and the results are shown in Fig. 2.
For this thought experiment, a percentage of sites, varying from 5% to 25% had local enhancement of sea level rise, presumably caused by increased groundwater use beginning somewhere from 1950 to 1970 and ending some time between 1970 and 1995. Start and stop times were randomized as it was assumed that local effects would not be synchronized around the world. Similarly, the amount of subsidence cause by water pumping was allowed to uniformly vary up to 5 mm/yr. The results show that even if a full quarter of all sites had significant time varying local subsidence, one would expect that the overall effect on the complete local sea level acceleration record to be significantly less than the PNAS2018 acceleration value. So, yes, local effects can show up as oscillations in the global sea level rise, but the effect is likely to be small compared to the variations calculated by the complete PMSL dataset. To get the wiggles seen in Fig. 2 to compare with the PNAS2018 value, you need to squint and increase the rate of subsidence and/or increase the percentage of sites with manic pumping.
Results
The results of compiling all of the tide gauge record data are shown in Fig. 3. The sites were sorted into 5×5 degree latitude and longitude grid cells and for each month of the record, an error weighted average for every cell was calculated. To combine the information over the set of 321 grid cells that contributed to the record, a weighted average that included both error and grid cell area was calculated. The record plotted in Fig. 3 has been smoothed by removing the 3 highest frequency components from its CEEMD decomposition. The light blue shading in Fig. 3 shows both 1 and 2 sigma error bars and the results of the 25% local pumping study shown in Fig. 2 is shown for comparison. Note that as the number of sites contributing to the record increases with time (see Fig. 1), the width of the error bars shrinks. Note that my global historical sea level rise record agrees quite well with the PNAS2018 value.
To interpret what the record may mean, it’s important to note that whenever sea level acceleration equals zero, this corresponds to either a local maximum or a local minimum of the sea level rise relative to a constant linear trend. With that in mind, I estimate that there were local minima around the following years: 1883, 1902, 1922, 1958, and 1977. Local maxima occurred around 1893, 1915, 1940, and 1965. I’m trying to ignore minor excursions either plus or minus. We’ve been in a fairly protracted period of positive acceleration since 1977, but we flirted with deceleration around 2003. My estimate of the beginning of the positive acceleration is a tad later than that of Dangendorf et al. (2019). It’s certainly possible that some of the record is due to anthropogenic inputs, but is it “temperature” or “climate-change” driven? I try to address this question in Fig. 4.
Correlation or Causation?
Fig. 4 shows the raw, unsmoothed sea level acceleration record, with annual variations included, compared to the HadCRUT4 sea surface temperature (SST) acceleration. Error estimates are included for the sea level record, but for clarity they are not included for SST. Typical SST errors are visually similar in size at this scale to sea level errors after about 1950. The overall correlation coefficient for the two functions since 1880 is 0.44 with a lag of zero months. As shown in my previous post, that’s not really a very high correlation coefficient for a function with this degree of autocorrelation. However, just by eye, it seems that there is some correlation, at least in the first half of the records. Something significant appears to have happened to both temperature and sea level at the end of the 19th and the beginning of the 20th century. Then sea level variations settle down a bit, but the two records still seem to be on the same dance card until about 1950 or so. However, after that, SST and sea level appear to become decoupled. See the large positive SST acceleration in the late 1960s, with nary a response from sea level. I think that sea level rise since about 1950 may have been significantly influenced by anthropogenic factors, but temperature is not likely to be the mechanism.
I’m just wildly speculating here, but I wonder if the variations seen in sea level acceleration since about 1950 might be caused by the building of large dam projects for decelerations, and mining of ancient groundwater for accelerations. The destruction of dams and/or the enhanced release of reservoir water, a so-called “snail darter” effect, could also lead to sea level rise acceleration. I don’t have the data on hand to say one way or the other, but it’s an interesting thought. A big caveat, however, is that the number of tidal gauge sites included in the record in its early part are measured in the dozens or scores, while near the end, they are measured in the hundreds. So it is quite possible that the correlation between sea level and SST in the late 19th and early 20th centuries is a coincidence.
In conclusion, I think that the sea level acceleration derived here from the entire tidal gauge record is close to the most you can squeeze out of the PMSL dataset. Of course, one could add in things like volcanic and ENSO effects, but to me those are just natural phenomena, the timing of which we neither fully understand nor can control. We may be affecting sea level rise acceleration, but it does not appear to be due to a rise in sea surface temperature. Could we then paraphrase Cassius by saying that the fault dear Brutus is not in our SUVs, but in our dams?
References
Dangendorf, S., Hay, C., Calafat, F.M., Marcos, M., Piecuch, C.G., Berk, K. and Jensen, J., 2019. Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change, 9(9), pp.705-710.
Nerem, R.S., Beckley, B.D., Fasullo, J.T., Hamlington, B.D., Masters, D. and Mitchum, G.T., 2018. Climate-change–driven accelerated sea-level rise detected in the altimeter era. Proceedings of the national academy of sciences, 115(9), pp.2022-2025.
Permanent Service for Mean Sea Level (PSMSL), 2022, “Tide Gauge Data”, Retrieved 09 May 2022 from http://www.psmsl.org/data/obtaining/.
Simon J. Holgate, Andrew Matthews, Philip L. Woodworth, Lesley J. Rickards, Mark E. Tamisiea, Elizabeth Bradshaw, Peter R. Foden, Kathleen M. Gordon, Svetlana Jevrejeva, and Jeff Pugh (2013) New Data Systems and Products at the Permanent Service for Mean Sea Level. Journal of Coastal Research: Volume 29, Issue 3: pp. 493 – 504. doi:10.2112/JCOASTRES-D-12-00175.1.
Nerem like so many at the University of Colorado are brainwashed.
https://docs.google.com/document/d/1Iq7T-ie4o-8w72KWzBuXulin3aZkCoMf97-mUlDM05I/edit
Frightening petition with its dedication to unproven assertions and adoption of beliefs shown to be most likely wrong. You cannot make lasting social progress by ignoring evidence contrary to your own. Geoff S
Frightening to me was that I received it from an MIT trained “Distinguished” Professor.
Chris, if you were a splitter/geologist you might be trained-certified-experienced in Sequence Stratigraphy. This subset of stratigraphy was discovered by EXXON geologists and geophyicists in the 1970’s, and is currently utilized by all oil exploration companies (and also by redbed exploration geologists for copper/vanadium/cobalt deposits). Sequence Stratigraphy has many different catigories for seal level effects and world-wide, single ocean, or local effects. Geologists are comfortable with 40 meters higher sea level and 140 meters lower sea level. Farting around with a few meters is, as one commenter put it, “a rounding error”.
Nevermind the quality, feel the width….
“A huge part of London will be underwater by 2050, new data has revealed.
The terrifying climate forecast predicts areas in the city that will regularly fall below sea level in 30 years’ time. The research, from Climate Central, a US-based news organisation, claims the risk of flooding could be three times higher than previously predicted.
It should be noted that these images are based on predictions if we make no cuts to emissions. Not only can you search by area, but you can actually search your own street.
These are the parts of London that will be submerged:”
https://www.mylondon.news/news/zone-1-news/see-your-street-underwater-2050-17212413
Well, that’s a new one. Climate Central, a US-based news organisation, can predict which streets will be affected in 2050
Has the IPCC been in touch with them?
Those parts of London below 1M are easily protected by dikes, or already are. And nearly all of London is higher than 10m,
….. or 20, or 30…
https://en-gb.topographic-map.com/map-kffs8/London/?popup=52.15034%2C-0.70038
Perhaps I should have added /sarc
I was just adding to your sarcosis….
Good man
I reviewed the same map, virtually all of London other than the Thames riverbed is at least 7 M above MSL, and the average elevation in the City is 42 M. At the current rate of SLR of about 7-8 inches per century, nobody in London will have anything to worry about for at least 34 centuries. Considering that it’s likely fossil fuels will be long gone by then, it seems like, as the Bard put it, “much ado about nothing”.
“A huge part of London will be underwater by 2050, new data has revealed”
So what?
Replace the underground trains with submarines.
Replace their diesel taxis with gondolas
Problems solved.
I’ve just read a article about Italy and Venice apparently there’s not enough water in the sea causing drought and empty canals in Venice but sea level rise is a disaster at the same time.
Global Warming can truly do anything.
Yes, I just found a picture of a Venice’s emptied canal with a motorboat stuck in the stinking mud: Indeed the southern Europe/Northern Mediterranean regions are under a strong anticyclone as high as 1035-1038 mBars that weighs on the sea level since early january thus lowering it by almost half a meter. Added with a temporary low tide of 40 cm, the SL may be currently found about 1 meter under its mean level.
In addition, the Adriatic NW/SE orientation helps in emptying its norther shores if a strong wind blows for long times from the NW direction, what frequently happens.
Sea level rise slowed down from about 1940 to 1980 because there was global cooling in that period. The actual cooling was later revised to near zero because cooling while CO2 was rising was inconvenient. So the data were arbitrarily changed by dishonest government bureaucrat “scientists’, which was science fraud. People knew how to read thermometers and compile a global average in 1975. Such a large revision was science fraud.
(see the first three charts of 16 temperature charts at the link below:
Honest Climate Science and Energy: 16 average temperature charts: The first five show Inconvenient average temperature data have been changed at will by goobermint bureaucrat “scientists”
When global warming resumed in 1975 it was not long before sea level rise returned to the prior rate of change. This is being called acceleration in the article, but maybe is better described as a regression toward the mean rate of sea level rise during periods of global warming, such as in the 1910 to 1940 global warming period.
Assuming UAH global temperature data are accurate, and there was no global warming in the past 101 months, the rate of sea level rise is likely to slow down again, to a rate consistent with a steady global average temperature.
The rate of sea level rise should correlate with the long term trend of global average temperature change. I would hesitate to describe that as acceleration or deacceleration, which seems technically accurate, but is deceptive.
One big contributor to sea level rise is increasing global temperatures, which heat seas and cause thermal expansion of water. Thermal expansion happens when water gets warmer, which causes the volume of the water to increase.
Other potential issues
Not enough tide gauges before about 1940 — pre-1940 data may not be useful.
Tectonic plates, the massive slabs of Earth’s lithosphere that help define our continents and ocean, are constantly on the move. Plate tectonics is driven by a variety of forces: dynamic movement in the mantle, dense oceanic crust interacting with the ductile asthenosphere, even the rotation of the planet.
“Sea level rise slowed down from about 1940 to 1980 because there was global cooling in that period.”
Those sea level charts closely resemble the unmodified surface temperature charts of the United States. They show highpoints in the 1880’s, and the 1930’s and they don’t show anything unprecedented today as compared to the past.
From the article: “Sea Level Rise: Hockey Stick or Roller Coaster?”
Global surface temperatures: Hockey Stick or Roller Coaster?
I say Roller Coaster.
Ja. Ja. We have evidence here of the water standing at least 30 meters higher than today, in the Cape (of Good Hope).
That must be as a result of the giants that lived earlier (UK?Doggersbank? going by Plato)
Could it be that an advanced civilization of giant people existed long before Noah’s flood? | Bread on the water
“We have evidence here of the water standing at least 30 meters higher than today, in the Cape (of Good Hope).”
That sounds like baloney to me. Maybe one meter higher, during the Holocene Climate Optimum, but not 30 meters. The evidence must be wrong.
Richard. Are you doubting me? Make a bet?
Must I make a picture of the page in the book? 30 m.
Anyway. They recently also found shells and shark teeth in the hills of the eastern Cape. I think they are still trying to put the history together.
The Nullarbor Plain in Australia is 180 metres above current sea level, yet there is evidence of an ancient sea in the mud layer, around 10 metres from the surface.
Think about this. 71 % of the planet is ocean averaging 3700 meters deep. 29% of the planet is land averaging 800 meters high. If the sea bottom rises by 1 cm on average, land must fall by 2.4 cm.(again on average) assuming the planet total volume remains constant. Such a change would appear to be “sea level rise”. Do we monitor ocean depth to sufficient accuracy to determine how much those rafts of silicates are floating on the molten iron underneath ? And the response of the quite plastic crust to those forces of buoyancy that ultimately determine the amount of land that protrudes above sea level. The answer is “NO”…
…you heard it here first…maybe…story tip….
While we’re considering crustal mechanics, did you know the molten iron core grows by a mm per year ? Of course the scientists saying this have never been there with a tape measure or thermometer and are using seismic waves not known for their mm round trip reflective accuracy at the necessarily long wavelengths used…. might this affect the rise of the sea floors mentioned in my above comment ?
Did you know the crust moves up and down daily by 8” to a foot due to land “tides”, same gravitational effect of the Moon and Sun as ocean tides.
https://www.theweathernetwork.com/ca/news/article/mysterious-lopsided-cooling-points-to-strangeness-in-core-of-earth
University of Colorado’s page on GIA talks about sea bottom falling, and how that muddies up the sea level rise so they have to add on a fudge factor so what your lyin’ eyes see aren’t really right and they’re giving you what the sea level shoulda’ been, but ain’t. Or something like that, because it’s hard to measure, but it’s got error bars and it’s worse than you think.
Earlier in this century, I was watching the sea level on UColo’s site, and it ran around 3.2 mm, then drifted down past 2.8, then down around 2.7, then the page dropped off the site. A couple months later it was back online, and the rate was magically back to 3.2 mm. I had to search to find how they did it. GIA.
https://sealevel.colorado.edu/presentation/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-it
Glacial Isostatic adjustment wasn’t even taken into account until 2011, based on Pelletier’s studies of a decade earlier. It reduces SLR by .3 mm/yr roughly with 50% possible error. There are hundreds of tremors every day as the crust flexes from Lunar tides of 8” to a foot. I think a “gentle” rebound due to a 20,000 year old glaciers-that-used-to-be-there is still highly speculative, but sounds sciency. It could just as easily be due to changes in deep magma circulation patterns.
Nah, I have been blogging for at least 6 years that the whole exercise rests on the untested assumption that the ocean basins, the water containers, have constant volume, when we know that there is seafloor spreading, underwater volcanos, new islands forming at the surface, earthquakes changing local elevations above earth centre and so on. Even a change of the population of a profuse marine species like plankton can cause sea level to change. Bad science to close the eyes to errors. Geoff S
As we don’t even know the rate of sea level rise, computing an acceleration is not mathematically sound.
If you look at my original post, you will see that this is incorrect. Any linear rise in sea level does not affect the estimation of acceleration.
Use only tide gauges set on bedrock such as The Battery and you might get different results. Ground water pumping should not effect them.
So each plotted point in figure 3 represents sea level rise acceleration for the previous 25 years + 1 month, and that agrees with Nerem etal. 2018. Just remember that Nerem extrapolates that out to 0.65 meters of sea level rise over the next 82 years to 2100. If anyone agrees with that they should say why.
Author is still inculcating a confirmation bias where the author presumes false condition before starting an investigation.
Simple sea level rise is NOT automatically sea level acceleration!
The first error condition you should have investigated is what constitutes a ‘sea level acceleration’ condition.
Historical and present incremental sea level rise does not show sea level acceleration.
I only looked at sea level acceleration, not sea level rise.
Notice this is roughly a 20 year cycle, missing a minima at 1940 of course. The time differences in the minima I have are 19, 20, 36, 19 years.
I think, pumping may not have caused as great of an effect, as ‘draining the swamp.’ When agriculture became mechanized in the early part of the 20th century, wetlands were drained at a ferocious rate. According to old farmers I knew in the 1990s, the Southern Pacific Levee in the middle of the Sacramento Valley was the high tide line for the Sacramento – San Joaquin river delta when that rail line was built in the late 19th century. The area is dry farm land today (Lodi, California). In the 1930s, surface creeks flowed all year, the water table was 12′, today 175′ (Slough House, California). Lake Tulare was drained too. I know these are small potatoes compare to the ocean, but larger works likely happened around the world around the same time.
Figure 4 looks like a very long-period seiche. It would be interesting to overlay that with the eccentricity of near earth celestial objects. <just musing>
This reminds me of Willis’ recent article on global temp’s and sunspots where (visually) the correlations appear to be good prior to about 1985 (Fig. 9) but then the correlation breaks down.
Any thoughts on correlations blinking in and out?
Your guess is as good as mine. I just wanted to show what the data say. Being purely objective, I’d say the apparent correlation in the early part of the record is weaker than the lack of correlation at the end of the record. I don’t really know in detail what causes apparent sea level rise acceleration, but I’m pretty sure that decadal scale temperature variations aren’t the biggest drivers right now.
Chris,
Thanks for your contribution and for including words on uncertainty.
Your figure 4, as you note, seems better correlations are for early data rather than recent.
It looks like that visually.
However, the early data (esp the temperature data) are the most uncertain and have the highest proportion of made-up values, call them imputed or interpolated or guesses. You cannot do formal uncertainty estimates on guesses. You have to accept that at least some % of the early values were accepted BECAUSE they agreed with sea level change. Your early SST uncertainties are much larger than those mathematically derived, perhaps by an order of magnitude. Evidence is in the adjustments created for bucket sampling versus ship engine intakes and preferential sampling of shipping lanes. This uncertainty has to be carried through to the acceleration figures. Geoff S
No “made up” or “filled in” data were used. Only PMSL data went into the curve, and you can do an error estimate on the 2nd order polynomial fit through the real data. If fewer than 200 points were available for a specific site and time, no value was calculated.
I scanned comments a coupla hours ago and something set me off – to go mangle a few decimals.
I started with the Yellow River – so called because of all the silt it carries.
Pretty gobsmacking numbers:
Annual flow: 56 cubic kilometresAverage silt content: 34kg per cubic metreDo please check this but I took silt to weigh 3,000kg per cubic metre and the world’s ocean to be 3e14 square metres.
Running that through gives 0.002mm of depth of silt over the ocean floor per year from the Yellow River
Which would be = Sea level rise due to Archimedes principle
So lets extend that to when it rains on farmland everywhere, when every river draining those lands becomes its own little Yellow River
Follow this one:
World farmland: 1e14 square metres (20% of planet area)Average annual rainfall over same= 600mmSilt load (50% of yellow flow): 15kg per cubic metreRunning that through I get a very scary but rather familiar number.
I get a sea level rise from muddy water coming off farmland of 1mm per year.
There’s your sea level rise, simply by using Archimedes Principle and looking out of your window on a rainy day
The World is Cooling.
Yeeeeesssss, temperatures are maybe seen to be rising, but Planet Earth is losing energy to outer space
edit to forgotten bit:
It was reckoned by ‘some’ that the Amazon Forest was/is fertilised by dust coming off the Sahara, crossing the ocean on the wind and snowing down on the trees when it got there.
To the tune of 40 million tonnes every year
OK maybe, but its a pretty major and hazardous trip for a teeny weeny grain of dirt.
If 40 million grains actually make it all the way across the water, how many fell into the ocean in making the attempt?
Chris, I really enjoy your posts and appreciate the work that goes into them.
However a small request…could you please not put images behind your graphs…Willis uses the same technique and it’s a pain…perhaps it looks prettier to some eyes but to me it’s just a distraction and makes it considerably harder to examine the graph to get at the data. When I look at a graph I’m after concise scientific information, not a pretty or clever image.
Maybe it’s just my eyes but I wonder if others have the same issue. Or am I just a grumpy old fart? (Don’t answer that!)
I thought it was just me. It’s too ‘folksy’. It takes something away from the science.
If it was images of cats, then it would be ok.
I’ll consider it, but inserting some jokes here and there is an important motivation for me.
Thanks Chris,
It’s not so much that it’s a joke or not, it’s just that it confuses the data you’re trying to present. This is especially obvious in fig. 2 it’s really hard to read the blue PNAS line of text and in fig. 4 the dam makes it hard to see the error bars in light blue. Fig. 1 with the ‘Where the boys are” text makes it hard to immediately grasp that it’s a log axis. Also that is one graph I could never show to anyone, especially people at our local government council or in fact anyone I might want to make a presentation to…they would just laugh at me for producing an unscientific graph!
There’s a lot of interesting and useful science in your graphs and it’s a shame to contaminate them with unnecessary this noise I feel.
See above.
I don’t have any problem with readability. I’m using Linux/Firefox. Could that make a difference?
I recall reading a study years ago, which examined the effects on sea levels of the 2010-11 La Nina flooding event. I personally experienced the massive flooding that took place in Queensland, Australia. The recents floods during the past couple of years were not as bad as the 2010-11 floods, at least in Brisbane, Queensland.
Here are a couple of articles that explain the effects that the massive 2010-11 flooding had on global sea levels.
“In mid 2010 to mid 2011, global mean sea level (GMSL) dropped by ~5 mm.
Heavy rainfall in 2010 led to increased terrestrial water storage in these regions. The El Niño Southern Oscillation is known to affect precipitation and evaporation over Australia and northern South America. In the El Niño phase it rains less, and in the La Niña phase it rains more. With the 2010-11 La Niña being one of the strongest over the past 60+ years, a large amount of water was transported from the ocean to the continents and led to the temporary drop in GMSL.”
https://podaac.jpl.nasa.gov/DataAction-2012-10-08-GRACE-GMSL
“The rains led to the formation of vast inland seas, Fasullo said, including the Lake Eyre Basin in eastern Australia, which went from “a small lake to a body of water that you couldn’t see across.” The Lake Eyre Basin covers about one-sixth of Australia, and is equivalent in size to the state of Texas. It contains the largest ephemeral lake in the world, which expands dramatically during times of abundant rainfall and ceases to exist in more arid times.”
https://www.climatecentral.org/news/floods-in-australia-briefly-slowed-sea-level-rise-study-finds-16373
Watched a documentary on the Zanzibar chain of islands. The big thing that stuck with me was the narrator comment that about 135,000 yrs ago the level of the Indian Ocean, which must have effected all oceans, dropped several meters. No explanation. The Indian Ocean still is not back to where it once was. See attached.
I drilled 2 of the stillstands in the late 1960s, identified by Bainbridge as far back as 1960 and described in Principles of Physical Geology, Holmes in 1964. When this description is coupled with Dietz’s advancing (and retreating) paralic wedge theory, in his book on sedimentology, then the reason for large remnant heavy mineral deposits off the east Australian coast becomes apparent. The advancing paralic wedge takes with it most of the beach profile and moves it up the slope to the modern-day beach layout. The advance and retreats that Bainbridge described onland through the mapping of terminal moraines, represent the much smaller equivalent of the modern-day heavy mineral sand deposits (I have also visited a few of them in Indiana, USA – they are host to small alluvial gold occurrences) are reflected on the continental slope – see attached diagram. What is interesting to note is that rapid sea level rises and falls occurred far faster than anything we witness today.
In short, Bainbridge’s locations were most accurate (I drilled a significant part of the continental shelf from Bermagui, NSW to South Stradbroke over a 3 year period). The most recent still stand was not drilled due to its close location to the shoreline. Lower still stands were occasionally mapped at the time but considered too deep for possible development and remain unexplored. Regretfully, most of the raw data is lost.
Thanks, very interesting. Looks a bit like there is an approximately 1500year oscillation occurring since about 5500BP. I’ve not seen that so well illustrated before.
This paper ( Relative sea-level rise and land subsidence in Oceania from tide gauge and satellite GPS (degruyter.com), based on 5 GPS-corrected tide gauges on Pacific shores strongly contradicts the mean SLR satellite records with almost negligible accelerations.