01. 2012年6月04日 17:13:27 : 3CNLte9sGM
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11123.html

A signature of cosmic-ray increase in AD 774–775 from tree rings in Japan

Fusa Miyake1, Kentaro Nagaya1, Kimiaki Masuda1 & Toshio Nakamura2

Increases in 14C concentrations in tree rings could be attributed to
cosmic-ray events1–7, as have increases in 10Be and nitrate in ice
cores8,9. The record of the past 3,000 years in the IntCal09 data
set10, which is a time series at 5-year intervals describing the 14C
content of trees over a period of approximately 10,000 years, shows
three periods during which 14C increased at a rate greater than 3%
over 10 years. Two of these periods have been measured at high
time resolution, but neither showed increases on a timescale of
about 1 year (refs 11 and 12). Here we report 14C measurements
in annual rings of Japanese cedar trees from AD 750 to AD 820 (the
remaining period), with 1- and 2-year resolution. We find a rapid
increase of about 12%in the 14C content from AD 774 to 775, which
is about 20 times larger than the change attributed to ordinary solar
modulation. When averaged over 10 years, the data are consistent
with the decadal IntCal 14C data from North American and
European trees13. We argue that neither a solar flare nor a local
supernova is likely to have been responsible.

Figure 1: Measured radiocarbon content and comparison with IntCal98.

The concentration of 14C is expressed as Δ14C, which is the deviation (in ‰) of the 14C/12C ratio of a sample with respect to modern carbon (standard sample), after correcting for the age and isotopic fractionation30. a, Δ14C data for tree A (filled triangles with error bars) and tree B (open circles with error bars) for the period AD 750–820 with 1- or 2-year resolution. The typical precision of a single measurement of Δ14C is 2.6‰. Most data were obtained by multiple measurements, yielding smaller errors. Error bars, 1 s.d. b, The decadal average of our data (filled diamonds with error bars) compared with the IntCal98 data13 (open squares with error bars), which is a standard decadal Δ14C time series. Six standard samples (NIST SRM4990C oxalic acid, the new NBS standard) were measured in the same batch of samples. Because Δ14C is calculated as the deviation of the 14C/12C ratio of a sample with respect to an average of 14C/12C of the six standard samples, the errors are the resultant of error propagation. An error for a sample is a statistical one from a Poisson distribution, and an error for the standard sample is the greater of either averaged statistical error from a Poisson distribution of Δ14C for the six standard samples or the s.d. of values of 14C/12C for six standard samples.

http://www.nature.com/nature/journal/vaop/ncurrent/fig_tab/nature11123_F1.html

02. 2012年6月04日 17:17:57 : 3CNLte9sGM
The increment of 14C content in AD 775 was about 12%. The source
cannot be the solar cycle (that is, the Schwabe cycle), which on average
has an 11-year period and an amplitude of 3%with respect to its effect
on the atmospheric 14Cconcentration5. An increase of 12%in 1 year is
about 20 times larger than expected from the Schwabe cycle. Only two
known phenomena can change the cosmic-ray intensity within 1 year:
a supernova explosion or a large solar proton event (SPE).
First we consider the increase of 14C content due to a supernova
explosion. In this case, c-rays can produce 14C because c-rays are unaffected
by the Galactic magnetic field, unlike other charged particles
from supernova explosions. The production mechanism is the reaction
14N(n,p)14C from secondary neutrons of energy 10–40MeV produced
in the cascade from hard c-rays in the atmosphere. No detectable
increase in 14C corresponding to supernovae SN 1006 and SN 1054
was reported4, and the energy of the event in AD 775 at the Earthmust be
larger than these. We assume that the differential energy spectrum of
c-ray emission from a supernova is described by a power law with an
index of22.5 (ref. 4). By integrating over c-ray energies above 10MeV,
we obtain a 14C production yield of 1.23102 14Catoms erg21. We
computed the production yield of 14C due to c-rays using the
GEANT4 simulation code with QGSP-BERT-HP17, which is valid
for thermal neutron interactions. Based on this figure, the incident
c-ray energy necessary for this increase of 14C content in the atmosphere
is about 731024 erg. If the distance of the supernova were the
same as that of SN 1006 (2 kpc; ref. 18), the total c-ray energy would be
331051 erg. This energy release is 100 times larger than the c-ray
energy release from a normal supernova assuming that 1% of total
supernova energy goes to c-rays and that emission of energy is isotropic
(typical total supernova energy is of the order of 1051 erg).
Therefore, the supernova was closer than 2 kpc, so that the total
c-ray energy release is 331051 erg, which is a typical supernova
energy. However, although there are no historical records of a supernova
visible in the Northern Hemisphere around AD 775, there are
historically unrecorded supernova remnants: for example, Cassiopeia
A, which was found by radio observations, or Vela Jr (RX
J0852.024622), which was found by theCOMPTEL c-ray observatory,
based on the 44Ti line; the distance to Vela Jr is hundreds of parsecs and
its age is 103–104 years (refs 19–21). Therefore, we cannot rule out an
undiscovered supernova remnant corresponding to the AD 775 event.
But a supernova in AD 775 may be not probable, because a supernova
that occurred relatively recently and relatively near Earth should still be
tremendously bright (in radio, X-rays and 44Ti), and such an object is
not observed.
Next we consider the case of an SPE. We assume that the flux of
protons from an SPE as a function of rigidity (which is themomentum
of the particle divided by the electric charge) is exponential: exp(2R/R0),
where R is the rigidity of protons and R0 is the characteristic rigidity of
the SPE. R0 is set to 78MV (ref. 5) in the following calculation. Unlike
c-rays, protons reaching the Earth are blocked by the geomagnetic
field. We applied predicted (using EXPACS22 software) vertical geomagnetic
cut-off rigidities on the Earth for an assumed geomagnetic
field the same as the present field, and calculated the flux at intervals of
10u in latitude, and obtained an average 14C production yield of 10
14Catoms erg21 using the GEANT4 code. The total proton energy
necessary for this event was estimated to be 831025 erg at the Earth,
which corresponds to 231035 erg at the Sun and may be compared to
the total proton energy of 1029–1032 erg in a normal SPE23.
Because there is a 30% increase in the decadal 10Be flux record in
Dome Fuji from AD 755 to 785, we compared the production rate of
14Cwith that of 10Be (further discussions are presented in Supplementary
Information.) It is possible that an SPE with an extremely hard
energy spectrumcould explain simultaneously the 14Cand 10Be results,
but it would have to be much harder than any flare observed so far.
Furthermore, an annual time series of 10Be flux would be necessary for
a meticulous comparison. In fact, very large, energetic ‘super flares’
have been detected on normal solar-type stars. However, it is believed
that a super flare has never occurred on our Sun, due to the absence of
an historical record (such as a record of aurora and mass extinction
caused by the expected destruction of the ozone layer24) and theoretical
expectations25–29.
With our present knowledge, we cannot specify the cause of this
event. However, we can say that an extremely energetic event occurred
around our space environment in AD 775. In the future, other highresolution
records (such as 10Be and nitrate data), together with careful
research of historical documentation around AD 775 and further surveys
of undetected supernova remnants, may help us to clarify the cause.

03. 2012年6月04日 17:28:41 : EszHBBNJY2
16世紀17世紀の寒冷化時と比べて、技術は雲泥の差があるわけで、
アメリカのシェールガス大増産や、自国開発を後回ししていた大規模油田開発も
GOを出したのはこういうこと？
日本も真剣に補助金出して、海底から凍ったガス、メタンハイドレードを
掘削抽出する技術と実用化に向けて、スロットルを開かないと乗り遅れるぞ。

04. 2012年6月04日 17:48:45 : EszHBBNJY2
寒冷化でどの程度、食物生産が減退するかだよね。
輸入に頼っている国は、危ないし今も食料が満足に手に入らない国はさらに危ない。
隣国の戦争に巻き込まれるのは必然だよな。
国々は食糧を求め外国には輸出は一切しなくなり輸入に頼っている国は
じり貧状態。
下手すると食糧を求め戦争に突入する国もあるかもしれない。
中国や北朝鮮が不安定化するだろう。
中国がアフリカに持っている権益も消えるかもしれない。
中国のように権益を守るために軍隊を動かしたり、
北朝鮮のように食料確保で軍隊を動かすだろう。
>>03　に記載したけど、後エネルギーで軍隊を動かす国も出てくる。