How well do state-of-the-art climate models simulate sea level?

Posted: November 21, 2022 by oldbrew in Forecasting, modelling, Natural Variation, research, sea levels
Tags:


Are the models wrongly expecting sea level rise to closely mirror the rate of increase in atmospheric CO2 content, in all regions? It seems it doesn’t work like that. The study itself says: ‘As for simulation of the interannual variance, good agreement can be seen across different models, yet the models present a relatively low agreement with observations. The simulations show much weaker variance than observed’.
– – –
According to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, the global mean sea level has risen faster since 1900 than over any preceding century in the last 3000 years, says Eurekalert.

This makes hundreds of coastal cities and millions of people vulnerable to a threat of higher water levels.

State-of-the-art climate models provide a crucial means to study how much and how soon sea levels will rise.

However, to what extent these models are able to represent sea level variations remains an open issue.

Thus, they should be evaluated before they can be adopted to forecast future sea-level changes.

In a paper recently published in Atmospheric and Oceanic Science Letters, Dr Zhuoqi He from the South China Sea Institute of Oceanology led a team to assess the performance of climate models in simulating the sea level over the low-to-mid latitudes of the globe.

The results indicated that the models simulated the long-term mean sea level relatively well. However, strong biases were apparent when the models tried to reproduce the sea level variance.

For example, almost all of them underestimated the interannual signals over the subtropics where strong western boundary currents prevail.

Full article here.
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Study — Performance of CMIP6 models in simulating the dynamic sea level: Mean and interannual variance

Comments
  1. […] How well do state-of-the-art climate models simulate sea level? — Tallbloke’s Talkshop […]

  2. Kip Hansen says:

    The study is about “dynamic sea level” — not something like regional sea level rise or global sea level rise or global mean sea level rise.

    I have not seen this metric used very often. It is defined in the paper as:
    “The dynamic sea level (DSL), defined as the local height of the sea surface above the geoid, is usually used to examine regional sea-level change. Due to the effects of climate change and natural climate variability, the redistribution of heat, salt, and mass in the ocean, and the response from wind change, the observed and predicted DSL are highly time-varying and uneven in space”.

    What they find is that “dynamic sea level” is chaotic in nature….basically only vaguely predictable.

    What can you do with a study that finds: “As for the interannual variance, the simulated DSL variance bears a good resemblance to observations over the tropics. ”

    “Resemblence”? Is that a scientific thing? Is there “bad” resemblence? How much more accurate is “good resemblence”? Dos that mean “kinds looks like”?

  3. Gamecock says:

    ‘State-of-the-art climate models provide a crucial means to study how much and how soon sea levels will rise.’

    Pants on fire.

    They aren’t models. They aren’t ‘crucial.’ They assume rise. They don’t account for changes in the earth’s crust.

  4. catweazle666 says:

    Ah, more computer games – sorry, models – of non-linear chaotic systems.
    They’ll never learn.

  5. About Sea Level Rise:
    A rising sea level would increase the Inertia of the Earth Crust.
    More Land Ice is near the spin axis of the rotating earth crust while much more ocean is near the equator where sea level rise would significantly increase the inertia of the spinning earth crust.
    Conservation of Momentum would slow the Rotation Rate of the Earth Crust. The Atomic Clocks were put in place to measure Time Extremely Accurately, in 1972. More Leap Seconds would need to be added more frequently, but Less Leap Seconds have been added to the time every decade since 1972. The last leap second was added in 2016 and none expected to be added.
    This is valid Proof that Sea Level is Lower Now than it was in 1972!
    Sea Level has Fallen for Fifty Years, yet they say it has risen and the rise rate is accelerating. If sea level Ever Rises, Added Leap Seconds will be an Immediate Indicator.
    Since there is Absolute Proof that they have lied about Sea Level Rise, it clearly follows that the rest of the Climate Alarmism is Also Lies!

    So, about how climate models simulate sea level, Not Even in the Right Direction.

  6. About Sea Level Rise:
    A rising sea level would increase the Inertia of the Earth Crust.
    More Land Ice is near the spin axis of the rotating earth crust while much more ocean is near the equator where sea level rise would significantly increase the inertia of the spinning earth crust.
    Conservation of Momentum would slow the Rotation Rate of the Earth Crust. The Atomic Clocks were put in place to measure Time Extremely Accurately, in 1972. More Leap Seconds would need to be added more frequently, but Less Leap Seconds have been added to the time every decade since 1972. The last leap second was added in 2016 and none expected to be added.
    This is valid Proof that Sea Level is Lower Now than it was in 1972!
    Sea Level has Fallen for Fifty Years, yet they say it has risen and the rise rate is accelerating. If sea level Ever Rises, Added Leap Seconds will be an Immediate Indicator.
    Since there is Absolute Proof that they have lied about Sea Level Rise, it clearly follows that the rest of the Climate Alarmism is Also Lies!

    So, “How well do state-of-the-art climate models simulate sea level?”

    Not even in the right direction!

    Not for the Most Recent Fifty Years of Accurate Measurements of Length Of Day!

  7. The topic for another posting is:
    “Current climate model simulations overestimate future sea-level rise”

    A good next topic should be:
    “Current climate model simulations overestimate past sea-level rise”
    Length of Day is Proof of that!

  8. Watch for the next Leap Second to be Added, Sea Level will not, cannot, rise without more and more Leap Seconds added more and more frequently.

    Sea Level is difficult to measure, it is difficult to average the measurements, they can, and do tell us sea level has risen, and that sea level rise is accelerating!

    The Atomic Clocks Just Say NO!

  9. oldbrew says:

    Leap Seconds Will Expire by 2035, Easing Time Trouble for Tech
    Nov. 21, 2022

    An international time standards group concludes that fine-tuning clocks to match Earth’s rotation is more trouble than it’s worth.

    Earlier leap seconds have been added to compensate for the Earth’s slowing rotation, but there’s evidence the rate is now speeding up. That would mean a leap second would have to be removed, and that’s never been tried.

    https://www.cnet.com/science/leap-seconds-will-expire-by-2035-easing-time-trouble-for-tech/

    There you have it – dated today. The problem for tech is that their systems would or could detect the same datestamp occurring twice if time runs backwards (from their point of view), which might confuse them – so to speak. Knock-on effects to some other systems could then occur.
    – – –
    BBC: The Earth’s rotation is changing speed: should we be worried?

    In 2020 scientists made a startling discovery. They found that, instead of slowing down, the Earth has started to spin faster. It is now spinning faster than at any time in the last 50 years. In fact, the shortest 28 days on record all occurred during 2020.

    https://www.sciencefocus.com/planet-earth/earth-rotation-speed/
    (dated 31/7/21)
    – – –
    Scientists have recorded Earth’s shortest day since its rotational period began to be recorded with highly precise atomic clocks: On June 29, 2022, Earth’s spin was completed in 1.59 milliseconds under 24 hours.

    https://www.space.com/earth-rotation-record-shortest-day

  10. catweazle666 says:

    “but there’s evidence the rate is now speeding up.”

    Indicating that the polar moment of inertia has decreased, hence mass appears to have been redistributed towards the poles…

  11. oldbrew says:

    We await an explanation of how Earth’s rotation speeding up and slowing down could both be due to humans burning fossil fuels 🤔

  12. Thanks for that information about Leap Seconds to Expire. I had not seen that.

    If you can add leap seconds, but you can’t subtract leap seconds, but you can do “some other adjustment”, then you are lying about the reasons.

    GPS depends on having a standard time, the standard time is the ticks of the Atomic Clock, our time is just an offset from the ticks of the clock to keep sun time correct.

    I think they realize an important part of their CO2 alarmism is the rising sea levels and the lack of more and more added leap seconds is too clear as an indicator that they are lying about sea level rise.

    They want to do some other adjustment, less often, so that they have less people realizing that earth’s crust is spinning faster. Checking their measurements and math on sea level rise is impossible, there are too many ways for them to lie and cheat, but they can’t cheat on time, too many people depend on it and are watching the clocks.

    Several years ago, I could enter “LOD or Length of Day” and find multiple sources that presented Length if Day in different ways. Now it is harder to find. But there is a plot in this link.
    https://www.timeanddate.com/time/earth-rotation.html
    Scroll down to: “How Far Back Does the Data Go?”, for a plot of Length of Day for 1830 to 2020

    This verifies that LOD is shorter than in 1972 when the Atomic Clock was put into service for standard time. It also shows that LOD is shorter than in 1900. When the LOD is sloped up, sea level is likely rising, when LOD is sloped down, sea level is likely dropping. Length of Day was much shorter during the major ice ages, when oceans were depleted of water and much ice was at high latitudes, closer to the spin axis.

  13. We have been adding leap seconds since 1972, before and after Y2K, to subtract a leap second, all we are doing is going back to where we were, we know everything worked then.
    They suggest changing something the whole world is now using to some different, some untried scheme, a scheme that lets sun time drift further away from correct before making larger, something different, corrections, I expect some push back, but I expected more push back on the evil green replacing reliable energy grids with intermittent grids that have us out of power for both Hot and Cold times and more transmission of energy from too far away to protect from man or nature.
    Europe was getting natural gas from Russia in a pipeline that has been destroyed with a bomb, instead of producing the natural gas from abundant supplies they are literally on top of, or using nuclear power from power plants that they shut down long before necessary, they cut off an energy supplies that were already paid for, nuclear and coal, they paid much more to try to replace it with wind and solar and see where that is headed.

  14. You wrote:
    Earlier leap seconds have been added to compensate for the Earth’s slowing rotation, but there’s evidence the rate is now speeding up. That would mean a leap second would have to be removed, and that’s never been tried.

    No, when the Atomic Clock started keeping Time in 1972, that was the beginning of adding Leap Seconds, the Length of Day at the beginning in 1972 was longer than the Atomic Clock day, Leap Seconds were added to match the difference. Since 1972, less and less leap seconds were added because actual Length of Day was catching up with the Atomic Clock Day. Leap seconds have been added, and likely will next be added, to correct for the mismatch between Atomic Length of Day and Actual Sun Time Length of Day. A measure of earth spin rate increasing or decreasing is not measured by an added leap second. The measure of earth spin rate increasing or decreasing can be measured by how the interval of added or subtracted leap seconds change. If you added leap seconds and you added the same number of leap seconds for multiple years, that would mean Length of Day did not change.

  15. oldbrew says:

    Moving 300-day LOD average (green line) goes below the zero line in 2020.

    Source — https://en.wikipedia.org/wiki/Day_length_fluctuations

  16. Ned Nikolov, Ph.D. says:

    Since the sea level rise (SLR) is supposed to be mostly a result of the thermal expansion of oceanic waters, there is a simple test to check whether or not the official SLR data are physically feasible. Global SLR should show a decent correlation with the global sea-surface temperature (SST). That’s because the top 250 – 300 m of ocean waters are well mixed and have a nearly uniform vertical temperature profile (see https://www.pmel.noaa.gov/gosml/).

    This Figure shows the correlations between SLR, SST, Ocean Heat Content of the top 300 m, and atmospheric CO2 concentration according to official institutional datasets. The results raise a critical question: Why does SLR correlate so tightly with CO2 (r^2 = 0.99) while showing a poor correlation with SST?

    Don’t you think that it would be physically impossible to obtain such results, if SLR was indeed based on real measurements?

  17. oldbrew says:

    Internal variability and forcing influence model–satellite differences in the rate of tropical tropospheric warming
    Santer et al, Nov. 2022

    Abstract

    Climate-model simulations exhibit approximately two times more tropical tropospheric warming than satellite observations since 1979. The causes of this difference are not fully understood and are poorly quantified.

    https://www.pnas.org/doi/10.1073/pnas.2209431119

  18. Ned Nikolov, Ph.D. says:

    @oldbrew,

    This is an interesting new paper acknowledging the long-standing and well-known overprediction of the mid-troposphere tropical warming by climate models:

    https://www.pnas.org/doi/10.1073/pnas.2209431119

    It’s been known in the past as the “tropospheric hot spot”, and some climate scientists have denied this important model departure from reality. However, the authors of the above paper adopted a backward method to assess the problem. Instead of training the machine-learning algorithm on observed data, they trained it on climate model output and then applied it to analyze the observations:

    In applying the climate-model-trained machine-learning framework to observations, we estimate that external forcing has produced a tropical TMT trend of 0.25 ± 0.08 K⋅decade−1 between 1979 and 2014, but internal variability has offset this warming by 0.07 ± 0.07 K⋅decade−1.

    This approach implicitly assumes that climate models correctly simulate physical reality including all important forcing, which is demonstrably wrong! For example, climate models are notoriously bad at reproducing observed cloud dynamics, which controls the solar forcing… The real reason for the modeled mid-troposphere tropical “hot spot” NOT to be observed in reality is because “greenhouse gases” such as water vapor do not trap heat in the troposphere as predicted by climate models. The tropical mid-troposphere is mostly heated by convection from the surface, while the surface is heated in turn by the incoming solar flux, which depends on the cloud albedo above the surface.

    [reply] copied this comment to the existing thread discussing the quoted paper:

    New analysis attempts to reconcile differences between satellites and climate models

  19. catweazle666 says:

    “In applying the climate-model-trained machine-learning framework to observations”

    So they are effectively getting self-modelling computer models to model computer models…

    Sounds back-to-front to me…

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