The ABCD Theory

Trees are a prolific example of biodiversity.

With an estimated 100,000 species, the number of trees worldwide might total twenty-five percent of all living plant species.
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Trees exist in two different groups of vascular or higher plants, the gymnosperms and the angiosperms. The gymnosperm trees include conifers, cycads, ginkgophytes and gnetales; they produce seeds which are not enclosed in fruits, but in open structures such as pine cones, and many have tough waxy leaves, such as pine needles.
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Trees are either evergreen, having foliage that persists and remains green throughout the year, or deciduous, shedding their leaves at the end of the growing season and then having a dormant period without foliage.
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The number of trees in the world, according to a 2015 estimate, is 3.04 trillion, of which 1.39 trillion (46%) are in the tropics or sub-tropics, 0.61 trillion (20%) in the temperate zones, and 0.74 trillion (24%) in the coniferous boreal forests.

https://en.wikipedia.org/wiki/Tree

Biodiversity is the variety of different types of life found on the Earth and the variations within species.

https://en.wikipedia.org/wiki/Biodiversity

This biodiversity is reflected in dendrochronology.

Dendrochronology, or tree-ring dating, is the scientific method of dating based on the analysis of patterns of tree rings, also known as growth rings.

https://en.wikipedia.org/wiki/Dendrochronology

For example:

Tree ring sensitivity [sudden change in growth conditions] has been associated with volcanism.

Dendrochronologists studying conifer tree rings [from living trees and subfossil tree remains] collected in Finnish Lapland identified seven [negative] outliers in their tree-ring sensitivity [sudden change in growth conditions] data: 4866 BC, 2850 BC, 2564 BC, 1464 BC, 330 BC, 536 AD and 1601 AD.

Fig. 1 A mid- and late-Holocene chronology of climatic downturns.
Tree-ring sensitivity (i.e., sudden change in growth conditions).
Please note that only negative departures are given, the values therefore indicating growth reductions.
A chronology of climatic downturns through the mid- and late- Holocene: tracing the distant effects of explosive eruptions from palaeoclimatic and historical evidence in northern Europe
Samuli Helama, Jari Holopainen, Marc Macias-Fauria, Mauri Timonen, Kari Mielikäinen
Polar Research – Volume 32 – 2013
http://www.polarresearch.net/index.php/polar/article/view/15866

The ingenious dendrochronologists also used their tree-ring data to reconstruct summer [July] temperatures from which they identified a slightly different set of six [negative] outliers: 2564 BC, 1584 BC, 874 BC, 330 BC, 536 AD and 1601 AD.

The dendrochronologists then concluded [via the sulphate data in the Dye 3, GRIP, NGRIP and GISP2 Greenland ice cores] that their 1601 AD and 536 AD outliers might have been caused by volcanism and this led them to think “the same causal relationship can be implied further back in time”.

Calendar year dates when the tree-ring signatures (i.e., growth reductions and reconstructed temperatures) were concurrent were compared with sulphate data from Greenland ice cores.

Previous new evidence are in agreement in demonstrating volcanism behind late-Holocene events in 1601 A.D. and 536 A.D., suggesting that the same causal relationship can be implied further back in time.

Our data show that earlier events were found to have occurred in the years 330 B.C., 874 B.C., 1464 B.C., 1584 B.C., 2564 B.C. and 2850 B.C.

Interestingly, events of lesser magnitude followed the three major events in 542 A.D., 1453 B.C. and 1579 B.C. by a few years.

A chronology of climatic downturns through the mid- and late- Holocene: tracing the distant effects of explosive eruptions from palaeoclimatic and historical evidence in northern Europe
Samuli Helama, Jari Holopainen, Marc Macias-Fauria, Mauri Timonen, Kari Mielikäinen
Polar Research – Volume 32 – 2013
http://www.polarresearch.net/index.php/polar/article/view/15866

For example:

Narrowest tree ring events [severe environmental downturns] have been associated with cometary debris [after having been previously associated with volcanism].

In 1988 Mike Baillie associated a narrow tree ring event beginning in 1628 BC with a Santorini volcanic eruption.

There has recently been renewed interest in the dating of the violent eruption of the Aegean island of Santorini in the second millennium BC, both by its possible effects on tree-ring growth in the United States (suggesting a date of 1628–1626 BC), and by acidity peaks in ice cores from South Greenland (suggesting 1645 BC).

We now show that oak trees growing on bogs in Northern Ireland produce significant concentrations of extremely narrow rings within a few periods less than 20 years long and that these periods correspond to the dates suggested by other methods for major volcanic eruptions.

In particular, one of them, corresponding to a short period beginning in 1628 BC, was probably caused by Santorini.

This date is qualitatively better than those derived from carbon-14 or ice cores, because it is based on an absolute tree-ring chronology.

Irish tree rings, Santorini and volcanic dust veils
M. G. L. Baillie & M. A. R. Munro
Nature 332 – 24 March 1988
http://www.nature.com/nature/journal/v332/n6162/abs/332344a0.html

Nowadays, Mike Baillie associates the 1628 BC event [amongst others] with cometary debris.

Upon examining the tree-ring record, Baillie noticed indications of severe environmental downturns around 2354 BC, 1628 BC, 1159 BC, 208 BC, and AD 540.
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He believes that impacts from cometary debris may account for most of the downturns, especially the AD 540 event.

https://en.wikipedia.org/wiki/Mike_Baillie

The dates of a series of narrowest ring events (dates where numbers of long-lived oaks showed catastrophically narrow growth rings at the same time) have been identified in a long Irish oak tree-ring chronology (Baillie and Munro 1988).

Tree-Rings Indicate Global Environmental Downturns That Could Have Been Caused By Comet Debris – M G L Baillie
Comet/Asteroid Impacts and Human Society: An Interdisciplinary Approach
Editors: Peter T. Bobrowsky and Hans Rickman
Springer – 2007
http://www.springer.com/us/book/9783540327097

Thus we arrive at the curious situation where the 536 AD event in Finland is associated with volcanism [via the sulphate data from Greenland ice cores] whilst the 540 AD event in Ireland is associated with cometary debris [via a “more logical jump”] because there is no volcanic-acid signal in the Greenland ice cores between 536 AD and 545 AD.

It is now known, on the basis of three replicated ice cores (Dye3, GRIP and NGRIP), that there is no significant volcanic-acid signal in the time window 536–545 (Clausen et al. 1997).

The latest statement states specifically:

With the chemistry and the isotope data it is possible to do a very precise dating for the eruption.
The volcanic eruption is dated to AD 527 ± 1 year.
The AD 527 volcanic eruption is the only eruption in the period (Larsen et al. 2002).

The authors go on to say that this volcano is the only likely candidate to have caused
the 536–545 global event, but that the dating ‘suggest(s) that the event is not the same
one described by other sources’ (Larsen et al. 2002).

There are two ways to deal with this observation. One option is to disregard the dating by the ice-core workers and simply assume that 527 ± 1 really means 536 or 540 – there are currently no compelling arguments for moving the date derived from three replicated ice-cores in this manner.

The other is to make the more logical jump, namely that the global environmental downturn was not volcanic in origin, but rather was caused by loading of the atmosphere from another source, presumably from space.

Tree-Rings Indicate Global Environmental Downturns That Could Have Been Caused By Comet Debris – M G L Baillie
Comet/Asteroid Impacts and Human Society: An Interdisciplinary Approach
Editors: Peter T. Bobrowsky and Hans Rickman
Springer – 2007
http://www.springer.com/us/book/9783540327097

This curious situation is further confused by the lack of support in the historical records for the cometary debris theory [for the severe environmental downturns seen in Irish oak tree-rings].

540 AD – The historical record is unnaturally thin.
208 BC – No comets [but dim Sun, crop failures, famine & deaths in China].
1159 BC – Hampered by poor dating in ancient times.
1628 BC – Hampered by poor dating in ancient times.
2345 BC – Hampered by poor dating in ancient times.

Mike Baillie has suggested the ammonium signal in the Greenland ice cores support his cometary debris theory for the severe environmental downturn in 540 AD.

Unfortunately for Mike Baillie, the largest spike in the Greenland ammonium signal is for 1014 AD which is not associated with a severe environmental downturn in the Irish oak tree-ring chronology.

The evidence suggests that these environmental downturns were wide-ranging catastrophic events; the AD 540 event in particular is attested in tree-ring chronologies from Siberia through Europe and North and South America.

This event coincides with the second largest ammonium signal in the Greenland ice in the last two millennia, the largest being in AD 1014, and both these epochs were accompanied by cometary apparitions.

Baillie explains the general absence of mainstream historical references to this event by the fact it was described in terms of biblical metaphors since at that time “Christian beliefs included the dogma that nothing that happens in the heavens could have any conceivable effect on the Earth.”

https://en.wikipedia.org/wiki/Mike_Baillie

However, downsizing the ABCD theory to focus upon [generic] meteoroid debris does yield some very interesting results.

Unfortunately, the meteoroid evidence doesn’t explain Mike Baillie’s marker dates in the Irish oak tree-ring chronology.

But the historical records of meteor observations from Korea might just explain the Little Ice Age because of their variable density banding [over the centuries] and their seasonal variations which markedly peak during the last quarter of the year.

The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period (Medieval Climate Optimum).
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It has been conventionally defined as a period extending from the sixteenth to the nineteenth centuries, or alternatively, from about 1300 to about 1850, although climatologists and historians working with local records no longer expect to agree on either the start or end dates of this period, which varied according to local conditions.

https://en.wikipedia.org/wiki/Little_Ice_Age

We have compiled and analyzed historical Korean meteor and meteor shower records in three Korean official history books, Samguksagi which covers the three Kingdoms period (57 B.C — A.D. 935), Goryeosa of Goryeo dynasty (A.D. 918 — 1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392 — 1910).
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We have also analyzed seasonal variation of sporadic meteors from Korean records.

We confirm the seasonal variation of sporadic meteors from the records of Joseon dynasty with the maximum number of events being roughly 1.7 times the minimum.

The Korean records are compared with Chinese and Japanese records for the same periods.

Major features in Chinese meteor shower records are quite consistent with those of Korean records, particularly for the last millennium.

Japanese records also show Perseids feature and Orionids/north-Taurids/Leonids feature, although they are less prominent compared to those of Korean or Chinese records.

Analysis of historical meteor and meteor shower records: Korea, China, and Japan
Hong-Jin Yang, Changbom Park, Myeong-Gu Park
Icarus 175 (2005) 215-225
http://arxiv.org/abs/astro-ph/0501216

The Korean meteor evidence [whilst being far from conclusive] is at least a viable explanation for the variability of the Little Ice Age and many of the chemical [and particle] anomalies found in the Greenland ice cores.

A meteoroid is a small rocky or metallic body travelling through space.

Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects.

Objects smaller than this are classified as micrometeoroids or space dust.

Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars

https://en.wikipedia.org/wiki/Meteoroid

The visible light produced by a meteor may take on various hues, depending on the chemical composition of the meteoroid, and the speed of its movement through the atmosphere.

As layers of the meteoroid abrade and ionize, the colour of the light emitted may change according to the layering of minerals.

Colours of meteors depend on the relative influence of the metallic content of the meteoroid versus the superheated air plasma, which its passage engenders:

Orange-yellow (sodium)
Yellow (iron)
Blue-green (magnesium)
Violet (calcium)
Red (atmospheric nitrogen and oxygen)

https://en.wikipedia.org/wiki/Meteoroid

See: https://malagabay.wordpress.com/2014/04/12/greenland-the-cape-york-iron-meteorites/

See: https://malagabay.wordpress.com/2014/04/15/deprecating-the-ovifak-iron-meteorites/

The Tunguska event was a large explosion that occurred near the Stony Tunguska River, in what is now Krasnoyarsk Krai, Russia, on the morning of 30 June 1908 (N.S.).

The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 km2 (770 sq mi) of forest and caused no known casualties.

The cause of the explosion is generally thought to have been a meteor.

See: https://malagabay.wordpress.com/2015/12/02/ammonium-2-the-aurora-ring/

FOOTNOTE
Many thanks to Louis Hissink [ https://lhcrazyworld.wordpress.com/ ] for pointing me at Korea.