Geomagnetic excursions Interglacial Termination Abrupt Climate Change

[Saul]

There are a series of papers that support the assertion that geomagnetic excursions cause Younger Dryas magnitude abrupt climate change events.

There is a geomagnetic excursion that correlates with the Younger Dryas abrupt climate change and with similar abrupt climate change events.

Looking at how the geomagnetic field has changed in the past (the frequency of reversals, the change in the periodicity of excursions during the current ice epoch, and the periodicity of the Younger Dryas type abrupt climate events, the following hypothesis can be formed.

The periodicity of the forcing event that causes the geomagnetic excursion is around 12 kyr. The same forcing event (smaller magnitude) causes geomagnetic jerks which are secular geomagnetic field changes (regions on the planet surface that have stronger normal or reversed polarity in reference to the current geomagnetic field configuration.

It appears the cyclic event that is forcing the geomagnetic field is external. The field changes are too closely spaced to be due to internal changes in the planet. As the liquid core is conductive rapid field changes in the liquid core induce counter fields in the conductive liquid which inhibits rapid field changes.

The Paleoclimatic data shows that the Younger Dryas cooling event occurred over 15 years in three 5 years steps. The entire Younger Dryas cooling event was complete in 40 years. The planet cooled from interglacial warm to within 25% of the glacial temperatures. Temperature in the North America cooled by around 18F. What is interesting is the Younger Dryas is one of a series of similar cooling events, including the termination of past interglacial periods.

During the glacial period the external forcing event has less affect on the geomagnetic field and planetary temperature as the planet is already cold and vast regions of the planet's surface is covered with ice sheets which insulate the planet's surface from the cyclic forcing event, and planetary temperature is already very cold so increased GCR has less effect.

The affect of the external cyclic event that is forcing the geomagnetic event it appears is dependent on the earth’s axis tilt at the time of the event, timing of perihelion, the eccentricity of the earth’s orbit, the distribution of the continents on the surface of the planet, and the area of the planet’s surface covered by ice sheets.

http://www.paleomag.net/members/qingsongliu/References/EPSL/Thouveny%20excursions%20since%20400%20ka%20EPSL%202004.pdf

Geomagnetic moment variation and paleomagnetic excursions since 400 kyr BP: a stacked record from sedimentary sequences of the Portuguese margin

A paleomagnetic study was performed in clayey-carbonate sedimentary sequences deposited during the last 400 kyr on the Portuguese margin (Northeast Atlantic Ocean). Declination and inclination of the stable remanent magnetization present recurrent deviations from the mean geomagnetic field direction. The normalized intensity documents a series of relative paleointensity (RPI) lows recognized in other reference records. Three directional anomalies occurring during RPI lows chronologically correspond to the Laschamp excursion (42 kyr BP),the Blake event (115-122 kyr BP) and the Icelandic basin excursion (190 kyr BP). A fourth directional anomaly recorded at 290 kyr BP during another RPI low defines the ‘Portuguese margin excursion’. Four non-excursional RPI lows are recorded at the ages of the Jamaica/Pringle Falls,Mamaku,Calabrian Ridge 1,and Levantine excursions. The RPI record is characterized by a periodicity of approx. 100 kyr,paleointensity lows often coinciding with the end of interglacial stages. This record sets the basis of the construction of an authigenic 10Be/9Be record from the same sedimentary sequences [Carcaillet et al.,this issue].

Spectral analyses of the RPI record reveal a dominant periodicity at 100 kyr,already reported
by other studies (e.g. [41,59,60]). The RPI and N18O records also present a phase shift of 18 kyr: RPI lows often coincide with the end of interglacial or interstadial stages. The geomagnetic moment loss (-30%) over the last two millennia deduced from archeomagnetic results (e.g. [38,39]) might foreshadow the next excursion for the end of our present interglacial, even though this loss started 2200 years ago from an exceptionally high geomagnetic moment value.

 

[Andre]

Sorry but this is really apples and oranges.

Yes, there have been an abnormal amount of geomagnetic excurions in the current Lachamps chron, but it has nothing to do with the Younger Dryas stadial.

See for instance Guyodo and Valet 1999 which concludes:

There is no correlation between these intensity dips and cold climate events, although such a correlation has been suggested.

Obviously the Younger Dryas has been associated with a erratic geomagnic reversal, known as the Gothenburg magnetic flip (Morner 1971), but that has only been found in one sediment core in the Botanical garden in Gothenburg. It has never been reproduced, despite vigourous attempts. But there was something wrong with that core. it was broken. Although it has never been officially withdraw, the Gothenburg flip is no longer considered (info oral lecture Prof Cor Langereis).

Reference:
Morner, R. A., 1971, Late Weichselian paleomagnetic reversal. Nature Physical Science, vol. 234, no. 52, pp. 173-174 (December 27, 1971).

 

[Saul]

Sorry but this is really apples and oranges.

Yes, there have been an abnormal amount of geomagnetic excurions in the current Lachamps chron, but it has nothing to do with the Younger Dryas stadial.

See for instance Guyodo and Valet 1999 which concludes:

Yohan Guyodo & Jean-Pierre Valet's 1999 work "cold adjusted" the proxy data base that was used to determine geomagnetic field strength. The "cold adjustment" increased the geomagnetic field strength inferred from the ocean floor sediments during periods when the planet was cold which makes it appear the actual change in geomagnetic field strength did not cause the cooling.

Subsequent geomagnetic field intensity proxy analysis used different proxies to find the "archeomagnetic jerks" which are abrupt secular (regional and hemispheric) changes to the geomagnetic field intensity with a periodicity of roughly 400 years. The secular geomagnetic field changes weakens the geomagnetic field temporarily in a specific region and hemisphere and changes the tilt of the field offsetting it from the rotational axis of the planet. The resultant archeomagnetic jerks is caused by the small version of what is forcing the geomagnetic field.

There are far too many archeomagnetic jerks and geomagnetic excursions for the forcing function to be due to internal liquid core changes. It appears archeomagnetic jerks, geomagnetic field excursions, and geomagnetic reversals are being forced by a significant cyclic solar event.

The same solar event is the reason for the anomalous planetary magnetic fields of Uranus and Neptune.

The Younger Dryas is not a unique event. The termination of past interglacial periods was due to the same solar event that abruptly forces the geomagnetic field. As noted above affect of the solar event on the geomagnetic field is dependent on the tilt of the planet, the timing of perihelion, and the eccentricity of the planet's orbit. The affect is also dependent on whether there is or is not ice sheets on the planet's surface (ice is an insulator) and the position of continents.

The solar event comes in a small, medium, large, and super large. An event cyclically abruptly changes the geomagnetic field has a significant amount of energy. There are other geological events that are forced by the same cyclic (period of the solar event is not fix but the event occurs again and again) solar event.

Are there connections between the Earth's magnetic field and climate? Vincent Courtillot, Yves Gallet, Jean-Louis Le Mouël, Frédéric Fluteau, Agnès Genevey

We review evidence for correlations which could suggest such (causal or non-causal) connections at various time scales (recent secular variation approx 10–100 yr, historical and archeomagnetic change approx. 100–5000 yr, and excursions and reversals approx. 10^3–10^6 yr), and attempt to suggest mechanisms. Evidence for correlations, which invoke Milankovic forcing in the core, either directly or through changes in ice distribution and moments of inertia of the Earth, is still tenuous. Correlation between decadal changes in amplitude of geomagnetic variations of external origin, solar irradiance and global temperature is stronger. It suggests that solar irradiance could have been a major forcing function of climate until the mid-1980s, when “anomalous” warming becomes apparent. The most intriguing feature may be the recently proposed archeomagnetic jerks, i.e. fairly abrupt (approx. 100 yr long) geomagnetic field variations found at irregular intervals over the past few millennia, using the archeological record from Europe to the Middle East. These seem to correlate with significant climatic events in the eastern North Atlantic region. A proposed mechanism involves variations in the geometry of the geomagnetic field (f.i. tilt of the dipole to lower latitudes), resulting in enhanced cosmic-ray induced nucleation of clouds. No forcing factor, be it changes in CO2 concentration in the atmosphere or changes in cosmic ray flux modulated by solar activity and geomagnetism, or possibly other factors, can at present be neglected or shown to be the overwhelming single driver of climate change in past centuries. Intensive data acquisition is required to further probe indications that the Earth's and Sun's magnetic fields may have significant bearing on climate change at certain time scales.

http://sciences.blogs.liberation.fr/home/files/Courtillot07EPSL.pdf http://geosci.uchicago.edu/~rtp1/BardPapers/responseCourtillotEPSL07.pdf

Response to Comment on “Are there connections between Earth’s magnetic field and climate?, Earth Planet. Sci. Lett., 253, 328–339, 2007” by Bard, E., and Delaygue, M., Earth Planet. Sci. Lett., in press, 2007

Also, we wish to recall that evidence of a correlation between archeomagnetic jerks and
cooling events (in a region extending from the eastern North Atlantic to the Middle East) now covers a period of 5 millenia and involves 10 events (see f.i. Figure 1 of Gallet and Genevey, 2007). The climatic record uses a combination of results from Bond et al (2001), history of Swiss glaciers (Holzhauser et al, 2005) and historical accounts reviewed by Le Roy Ladurie (2004). Recent high-resolution paleomagnetic records (e.g. Snowball and Sandgren, 2004; St-Onge et al., 2003) and global geomagnetic field modeling (Korte and Constable, 2006) support the idea that part of the centennial-scale fluctuations in 14C production may have been influenced by previously unmodeled rapid dipole field variations. In any case, the relationship between climate, the Sun and the geomagnetic field could be more complex than previously imagined. And the previous points allow the possibility for some connection between the geomagnetic field and climate over these time scales.

 

[Saul]

Check the graph of planetary temperature change out (figure 1. Increase the magnitude to 150%.) It is difficult for humans living in the current interglacial period to imagine a Younger Dryas type abrupt climate change. It seems physically impossible without a mechanism.

The city of Chicago was covered with a mile thick ice sheet during the last glacial phase. The city of New York is the center of an ice sheet due to high levels of snowfall on the ice sheet fed by the warm moist air from the Atlantic.

Current insolation at 65N matches the insolation during the coldest part of the last glacial period. When you look at figure 1, it is obvious that there is some massive cyclic event that forces the planet's climate. Orbital insolation changes are not causing what is observed.

From an analytical standpoint if one picks incorrect mechanisms (There are at least four paradigm type errors in geological science) the problem becomes impossible to solve. i.e. The method to solve the problem is to look at the anomalies as a group. i.e. If anyone fundamental mechanism is incorrect it is not possible to solve the problem or understanding the observations. Look at the data and then develop hypotheses as opposed to starting with a set of mechanisms and then try to adjust the mechanisms to match the observations. i.e. A mechanism has limits. An analogy would be Kelvin's assumption that the source of the sun's energy was gravitational collapse which would limit the age of the Earth to thousands of years as opposed to billions of years. An entire set of scientific hypotheses changed when it was accepted that the planet is billions of years old rather than thousands of years old. The point is accepting the observations and following their implications.

Comment:
An analogy of the issues that must be addressed to solve this problem is the discovery of tectonic plate motion. Prior to the creation of the tectonic plate hypothesis there were dozens of unexplained anomalies such a matching rare geological formations on the edges of continents that match the same rare geological formation on the adjacent continent, the fact that continental coastlines shapes fit together as pieces of a puzzle and so on.

The geomagnetic field was assumed to not be capable of rapid changes because it was assumed to be core generated. The geomagnetic liquid core based computer models are 100% theoretical (There is no data on liquid core movements, the models in question are not realistic due to computer limitations. There are unproven theoretical hypotheses.). The recent discovery of very, very, rapid geomagnetic field changes is a paradox. Something that is physically possible with a liquid core field generating mechanism. What should have happened, is geomagnetic science should have raised a flag that there is a paradox.

The discovery of abrupt climate change and the glacial/interglacial cycle is also a paradox. The climate models that purport to be able to produce a glacial/interglacial cycle do so by creating a model that is unstable, a knife edge model that can theoretically jump. The current data shows the planet resists forcing changes to climate. The recent glacial/interglacial oscillations are a paradox. Abrupt climate, Younger Dryas type climate changes is a paradox. There are no internal changes on the planet that can cause the planet's climate to abruptly change for over a thousand years.

A very, very, power forcing function is required to abrupt force the geomagnetic field. The same forcing function leaves its mark on the planet causing other geological anomalies such as super volcanoes and kimberlite pipes.

From Wikipedia:

The morphology of kimberlite pipes, and the classical carrot shape, is the result of explosive diatreme volcanism from very deep mantle-derived sources. These volcanic explosions produce vertical columns of rock that rise from deep magma reservoirs.

Figure 1. Benthic d18O record from DSDP Site 607 in the North Atlantic (solid line) plotted to a paleomagnetic timescale. The magnetic field reversals are marked, as well as the transition from a dominant 41 kyr to a 100 kyr world. B, Brunhes; M, Matuyama; J, Jaramillo; TOld, top of Olduvai; G, Gauss. Also shown is orbital obliquity (red dashed line).

http://rsai.geography.ohio-state.edu/courses/G820.01/WI05 climate history/2002PA000791.pdf

The 41 kyr world: Milankovitch’s other unsolved mystery by Maureen E. Raymo et al.

[1] For most of the Northern Hemisphere Ice Ages, from approx. 3.0 to 0.8 m.y., global ice volume varied predominantly at the 41,000 year period of Earth’s orbital obliquity. However, summer (or summer caloric half year) insolation at high latitudes, which is widely believed to be the major influence on high-latitude climate and ice volume, is dominated by the 23,000 year precessional period. Thus the geologic record poses a challenge to our understanding of climate dynamics.All serious students of Earth’s climate history have heard of the ‘‘100 kyr problem’’ of Milankovitch orbital theory, namely the lack of an obvious explanation of the dominant approx. 100 kyr periodicity in climate records of the last 800,000 years. However, few have considered an equally perplexing characteristic of Earth’s climate, one that similarly defies simple physical explanation yet dominates the Earth’s recent geologic record. We call this the ‘‘Milankovitch 41 kyr problem.’’ For the time interval extending back to the Brunhes-Matuyama boundary (0.78 Ma), an interval in Earth’s climate history dominated by the large (and largely unexplained) 100,000 year periodicity, Imbrie et al. [1992] definitively showed that the obliquity (41,000 year) and precessional (23,000 year) frequencies observed in climate records were direct linear responses, with physically appropriate lags, to high-latitude summer insolation forcing. However, during the previous two million years of Northern Hemisphere ice sheet growth, from approx. 3 million years ago to about 0.8 million years ago, global ice volume varied almost exclusively at the 41,000 year obliquity period. Because high-latitude summer insolation is always dominated by precession, we argue that these earlier climate variations cannot be understood within the current framework of the Milankovitch Hypothesis.

 

[Saul]

The discovery that Uranus and Neptune's planetary magnetic field is offset both from the planet's rotational axis and offset from the center of the planet should have been a clue that something is fundamental incorrect with the theory as to what creates a planetary magnetic field. Look at the Uranus and Neptune observations and then think of the cyclic abrupt changes to the geomagnetic field. Add the very recenting finding of a ribbon of gas at the edge of the solar system that is at right angles the planet's orbital plane about the sun. Think of what could abrupt change a planet's magnetic field.

The solar event exits the sun at the solar equator. This is a very, very, large event and is cyclic. Following the analog of the paradigm shift associated with accepting the planets, sun, stars, and so forth are billions of years old as opposed to 1000's of years old (the point is then one must solve the problem as it is then recognized as unsolved problem), from an astrophysical standpoint what is causing this observation? I have been looking at the astrophysical problem have found a whole set of astronomical anomalies that point to a mechanism. I will start a thread in the astrophysical section as I am starting to make progress.

The New Solar System, 4th Edition by J. Beatth, C. Peterson, A Chaikin

As Voyager approached Uranus in January 1986, we wonder if our experiences with symmetric magnetic environments of Earth, Jupiter, and Saturn would true for a planet that is quite literally spinning on its side. (My comment in relationship to Uranus’ orbit about the sun.)

An empirical relationship that relates angular momentum and magnetic moments, the “Bode’s law” of planetary magnetism, suggested that the magnetic moment of Uranus would be about one-tenth of Saturn.

We knew that the rotational axis of Uranus would lie, in early 1986, within 8 degrees of the planet-Sun line. If Uranus’s magnetic and rotational axis were nearly parallel, as is the case for other magnetized planets, (my comment in planets in the solar system), one pole would be pointed almost directly at the Sun and the a very unusual magnetospheric shape would be expected.

The planet’s magnetic moment is nearly the same strength as that predicted, but orientation is very different from our expectations. Uranus’ magnetic axis is tilted at huge 59 degrees from Uranus’s rotational axis and offset from the planet’s center.

Figure 18
The magnetic fields of Uranus and Neptune are remarkably – and unexpectedly – alike. The large offset from centre means that the field strength … It also means that the fields source cannot lie in the cores but rather must in a turbulent liquid mantle (my comment: A turbulent liquid that is offset from the planet's core? That is not physically reasonable. The planet should be spherically symmetrical about the planet's center.) where dynamo driving convection can be substained.

 

[Andre]

Maybe also consider this quotation of Alfred Wegener:

Scientists still do not appear to understand sufficiently that all Earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence. . . It is only by combing the information furnished by all the Earth sciences that we can hope to determine 'truth' here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw."

Planetary magnetism is only a part of that story. There is a lot more to consider. it should also be considered that even the things that we think we know may be different like for instance the Last Glacial Maximum around 20,000 years ago, with those mile thick ice sheets on America, when the Mammoths roamed the Siberian megafauna steppes; see this post.

So, before hypothezing all kind of new things, we should really wonder if we cover each and every aspect from the past with that.

 

[Saul]

Maybe also consider this quotation of Alfred Wegener:

Planetary magnetism is only a part of that story. There is a lot more to consider. it should also be considered that even the things that we think we know may be different like for instance the Last Glacial Maximum around 20,000 years ago, with those mile thick ice sheets on America, when the Mammoths roamed the Siberian megafauna steppes; see this post.

So, before hypothesizing all kind of new things, we should really wonder if we cover each and every aspect from the past with that.

How problems are solved is as important as the solution. In the case of Earth sciences there is curiously sufficient information now to solve the problem. As has happened in the past when people start to discuss the solution suddenly papers will be submitted with the solution.

The phrase "abrupt climate change" does communicate what has happened in the past. Dangerous, deadly abrupt cooling climate change perhaps would be better. What we have heard concerning warming which cannot occur because the planetary temperature governor regulates temperature is what has happened in the past to explain the glacial/interglacial cycle and the Younger Dryas type abrupt cooling events. The abrupt change to the geomagnetic fields interrupts the planet's climate regulator.

The abrupt event changes the geomagnetic field first in a secular manner and later over a thousand years of so is integrated by the liquid core to increase or decrease the net geomagnetic field intensity depending on the hemisphere and polarity of the strikes.

The initial secular geomagnetic field changes will therefore not affect the entire planet in the same manner. It is called secular because regions and one hemisphere is affected more than another. The secular geomagnetic field changes explains why in the middle of a glacial phase specific regions can experience warming.

What is missing from the discussion is the reality of what has happened in the past and what appears to happening again. The forcing function appears to be a specific solar event that is caused by an interruption of the solar magnetic cycle.

A cyclic solar event that is capable altering the geomagnetic field will have other affects, in addition to abrupt climate change.

This paper is interesting. The planet as this paper notes has been cooling for the last few thousand years.

http://epic.awi.de/Publications/Mac2000c.pdf

Holocene Treeline History and Climate Change Across Northern Eurasia

Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia. Treeline advance on the Kola Peninsula, however, appears to have occurred later than in other regions. During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern.

 

[Evo]

Closed pending moderation decision.