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Sea Level Changes Puzzle

  1. Apr 11, 2010 #1
    There is in the past significant very rapid rises and falls of sea level. As there is no mechanism to rapidly melt and reform ice sheets to explain the sea level rise and fall based on mass balance (more or less water in the ocean) specifically what is causing the rapid changes in sea level is not known.

    For example, during the cycle Heinrich events the sea level rises and then drops 10m to 15m. (see link below.)

    The controversy continues in the Holocene period.

    http://geochemistry.usask.ca/bill/courses/International Field Studies/Sea level.pdf


    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Apr 11, 2010 #2
  4. Apr 11, 2010 #3
    Perhaps if you explained in more detail what point you wish to make?
  5. Apr 11, 2010 #4
    During the Heinrich events which occur roughly ever 6000 years, the sea level rises and then falls 10m to 15m.

    If the entire Greenland Ice Sheet were to melt (2.85 million km³ of ice) global sea levels would rise 7.2 m (23.6 ft.) (IPCC 2001).

    There is no mechanism that can heat up the earth to cause the glacial phase ice sheets to melt and then reform in the Heinrich period roughly every 6000 years.

    Sea level can change due to mass increase, temperature changes, or due to changes to sea floor. I believe each of the three mechanisms has been ruled out as an explanation.

    There appears to be a four mechanism that can change the sea level.
  6. Apr 12, 2010 #5


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    The Heinrich events occurred during the last glacial period. The last one was about 12 thousand years ago, with the Younger Dryas.

    They have not occurred since the end of the ice age. If we are going to discuss these, remember that this is not the place to develop your own theories, but rather to explain what is being proposed and considered by scientists working on the subject.

    I have no idea what you mean by "The controversy continues in the Holocene period." The causes of the Heinrich events are still the focus of various alternative ideas, but there were none in the Holocene.

    It's long been considered one of the most likely causes of the Younger Dryas is a large discharge of water from the dwindling Laurentide Ice sheet. This has recently been fairly convincingly confirmed. See

    Another possibility considered by some researchers is that cooling in the Younger Dryas time was caused by a cometary impact. With the identification of the a likely flood path, I think this is now fairly well wrapped up in favour of the more usual megaflood hypothesis.

    Cheers -- sylas
    Last edited by a moderator: May 4, 2017
  7. Apr 12, 2010 #6
    I have to say that published figures present a rather different picture.
    I understand these Heinrich events are local to the (north?) Atlantic, not global.

  8. Apr 12, 2010 #7

    There are spiked sea level changes in this graph. I believe the recent data shows the spikes to be faster.

    There are Holocene sea level changes where the sea level changes and there is no known cause for the change. (The change is much smaller than the Heinrich event, however the point of looking at the specific change is to try to understand the mechanism.) The sea level change is not random. I will have a look to see if I can find something to discuss.



    The melt water pulse in the arctic ocean cannot explain the 1000 year Younger Dryas abrupt cold period. The North Atlantic drift current's affect on the European winter is a factor of 8 too small to explain the Younger Dryas cooling in terms of magnitude and the North Atlantic drift current would not be interrupted for a 1000 years by a melt pulse. Correlation does not prove causation.

    As I noted there are concurrent geomagnetic excursions that occur at the same time as the Heinrich events. That may or may not be relevant to the Heinrich event. There is also a question as to what causes the geomagnetic excursions.

    Observations are considered to be theory neutral. Rather than bringing a theory to explain the observations, a more effective or at least a different approach is let the observations led to the theory. (i.e. Discuss the observations independent of any theory.)

    Earth science is peculiar in that there are sets of mechanisms that are obviously incorrect based on current detailed analysis of the observations and mechanisms. It is interesting that there are current papers and articles that are pointing out the obvious faults in the mechanisms and the observational evidence is improving (paradoxes are now being identified as paradoxes).

    For example, the melt pulse explanation for the Younger Dryas 1000 year cooling event or the impact explanation for the Younger Dryas 1000 year cooling event. A melt pulse or an impact would cool the planet for a roughly a decade or two not a 1000 years based on climate model analysis. What is the point of repeating a mechanism that does not and never made physical sense. That is not science. Understanding what is or is not a paradox or what is or is not explained, is fundamental to the scientific process.

    The Heinrich events are cyclic very abrupt changes. Melt water pulses, impacts, and the binge purge mechanism does not explain the Heinrich events.
    Last edited: Apr 12, 2010
  9. Apr 12, 2010 #8


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    When you say "no known cause", you are misreading the research on this.

    When we work with the past, it is often not possible to state with confidence precisely which causes and effects are at work; but it is subtly misleading to say "no cause is known". The fact is, there are perfectly sensible hypotheses for the what might change sea levels. That we can't be completely confident to distinguish between all alternatives is not an adequate basis for you to make up some huge mystery.

    In fact, it is not actually all that easy to identify sea level changes in the Holocene, because most significant cause of changing water lines is isostatic rebound, as the continents actually rise, slowly, after the weight of ice sheets is removed.

    One of the best ways to learn about the real questions and problems and solutions in science is to look at review articles. The Quaternary Science Reviews journal is an excellent resource for such papers. For example:
    • Milne et al (2005). http://dx.doi.org/10.1016/j.quascirev.2004.10.005 [Broken]
    Holocene data from the Caribbean and the Atlantic coast of South America have been critically assessed and a subset of the best quality data are presented. These data cover a large north–south geographic extent and display a distinct spatial variation. We make the first comparisons of this data set to predictions based on a realistic model of glaciation-induced sea-level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the Holocene. The spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea-level change, with the ice-induced effect dominating the observed north–south trend. A best-fitting model is applied to estimate a Holocene eustatic signal from the observations. We find that the model-corrected data are consistent with a relatively rapid rise of 7–8 mm/yr in the early Holocene with a marked reduction in this rate around 7 cal. kyr BP. From this time until present, the model-corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than ~ ±1 m (eustatic sea-level equivalent).​

    If you think there is some grand mystery here, other than the conventional bog standard scientific work of trying to tease out the impacts of isostatic rebound, meltwater, thermal expansion, tides, and so on, then give a reference for it.

    There's another set of confident assertions with no adequate basis. I do not think you are accurately understanding the proposed mechanisms. There's a lot more at stake than merely the North Atlantic drift current. See

    Now who is mixing up correlation and causation? The real science on this does not simply infer causation from correlation; it actually identifies and tests hypotheses about causation.

    No reference is given for this odd claim. Show this alleged climate model analysis.

    The Heinrich events are not cyclic. Working out the full details is ongoing research, but it is not nearly the paradox you suggest. These events are pretty obviously involving sudden collapses of ice sheets. Precisely what precipitates a collapse is not clear; the but given the non-linear behaviour of melting ice sheets, such sudden collapses are bound to occur as the sheets retreat; whether driven by an external forcing or not. Working out all the consequences from the paleontological record gives plenty of scope for sorting out details.

    At this point, I think you need to actually give some reference that backs up your claims. There are, of course, competing hypotheses. I don't think you have any good basis to summarily dismiss any of the major proposals being considered.

    Cheers -- sylas
    Last edited by a moderator: May 4, 2017
  10. Apr 13, 2010 #9


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    I believe there is more of a misunderstanding here as opposed to a paradox.

    So, a little background. First; Heinrich events are a series of similar events that occured during the last ice age. They involved the transport of a lot of ice from an area near the Hudson straits out to the ocean. During these events characteristic gravel and sand were transported by ice burgs and deposited into the ocean.

    These events occured because a large ice sheet tended to form that was not stable. As the climate warmed and a little bit of ice melted, it would tend to rise sea levels. However, this slight rise in itself led to further instability and resulted in the quicker transport and melting of ice.

    Keep in mind that ice burgs can melt much faster than a comparable amount of ice on land. The reason is that the ice burgs are free to travel towards warmer tropical waters.
    So, while the planet as a whole may not be warming all that much, ice can be melting much faster than normal simply because ice is being transported much quicker than normal.
  11. Apr 13, 2010 #10
    Sea Level Controversy

    Almost half of the current 1.5 to 2.0 mm/yr of yearly sea level rise is not accounted for. In the recent past the data shows planetary sea level increasing and decreasing independent of planetary temperature. (i.e. The cause of the change is not increased or decreased mass (ice sheets melting or growing) or the expansion or contraction of the water due to temperature.)

    As measuring the ocean level is difficult without satellites to measure land and sea level accurately and as there was not accurate ocean temperature measure in the past these anomalies where assumed to be due to measurement inaccuracies.

    The measurement inaccuracies have been removed. What is required is a significant unexplained change recorded with modern instruments, if there truly is a paradox.

    The ocean has recently stopped rising. Based on what has happened in the past ocean levels should now start falling. (The ocean levels changes track the solar cycle however the temperature change associated with the solar cycle changes is too small and there is no lag therefore it appears the change is not due to solar modulation of planetary temperature. The ocean level increases when the solar magnetic cycle is high and decreases when it is low.)

    http://www.grdl.noaa.gov/SAT/pubs/papers/2004nature.pdf [Broken]
    Last edited by a moderator: May 4, 2017
  12. Apr 13, 2010 #11


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    None of your references support this ludicrous set of assertions.
  13. Apr 14, 2010 #12


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    Staff: Mentor

    Thread closed pending moderation.

    edit: greg: thread will remain closed
    Last edited by a moderator: Apr 15, 2010
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