A 2000-year historical perspective
The other supercycle, besides the Gleissberg, that most often is referred to in the present-day data, is a 200-year supercycle. The Gleissberg cycle is usually cited with one of two values, accurately as 78 years, inaccurately as 80 years, but the 200-year cycle has no agreed-upon value, mostly the values referred to are from 180 to 220 years.
Explicitly there is no 200-year cycle in the Elatina data, but I have interpreted that the 29.2 "sawtooth pattern" represents a cycle of 173 years, which means that it may be a variant of the 200-year cycle. In addition, the longest of the remaining Elatina supercycles is 105 years. There is also a 52-year cycle, which is not seen in today's data. One interpretation could be that the corresponding cycles today are 105 (weak) and 210 (strong) years. There are indications that the possible 200-year cycle really oscillates today. Would this hint to limits of 170 and 210 years in Elatina data, corresponding to from 180 to 220 years in today's data. That may mean a change in the Sun's cyclicity or in the Earth's rotation rate or rather a mixup of these both factors.
The Gleissberg cycle has no obvious subcycles (other than the seven basic cycles), but the 200-year cycle clearly consists of two parts of 100 years, which oscillate between 80 and 120 years and is intertwined with the Gleissberg cycle. It seems that the cycle 120/60/30 years or maybe more accurately 26.5/53/106/212 years are also weather cycles. At least at the moment (2001) the 200-year cycle seems to have a value of 211.4 years.
The following minima are minima smoothed by one sunspot cycle or 11 years (actually they are low maxima per cycle). The minima between the Sporer minimum in 1496+-1 and the Maunder minimum in 1695 is 198-200 years. The minima between the Maunder minimum and the Dalton minimum in 1815 is 120 years. There are indications of a warm spell beginning around 1755. Thus we have here a 55-60-year weather cycle: around 1870 began a cold spell which had its coldest phase around 1900, 1930's had a warm spell, 1960's had a cold spell, 1990's again a warm spell, which culminated in 1998. I predict that the Sun is now going towards low intensity, and the warm spell ends in the 2010's. The 2020's will again be a cold decade.
But everything is relative. The colder spells are not so cold as the earlier ones and warmer spells are a little warmer than the previous ones. This is caused by a larger oscillation, the 100/200/400-year oscillation. The Medieval warm lasted from about 930 to 1300, with an aftermath about 1350-1370. The Little Ice Age began after that getting a real escalation about 1400 and having two great (Sporer and Maunder) and some smaller really cold periods. After the first warm period about 1760-1800, there was the Dalton minimum from 1800 to 1830, from which we are now going again towards a warmer period, compared to the Medieval maximum.
"The disturbances of the early third century were nothing compared with what would follow the end of the Severan dynasty in 235 AD. The half century from 235 to 284 AD was a period of unparalleled crisis, during which the Roman Enmpire nearly came to an end... This is a period for which comparatively little documentation exists, but that in itself may be symptomatic... Barbarian incursions were frequent and ruinous between 248 and 268... It was Diocletian who, in a reign from 284 to his voluntary abdication in 305, quelled the barbarians, defeated usurpers, and at the same time initiated sweeping political and economic changes that transformed the nature of the Empire, and ensured its survival for a while longer... In the mid fifth century the West was gradually lost. Areas like Spain and Africa were temporarily or permanently lost to the barbarians... In 439 Vandals took Carthage... In the 20 years following the death of Valentinian III (455 AD), the Roman Army proper dwindled to nothing." (Tainter 1988, pp. 137-148).
Was there something like the Sporer minimum in the 200's and Maunder minimum in the 400's or rather vice versa as the following shows? What makes this a relevant question is that according to Schove there was only 7 cycles from 192 AD to 302 AD. This means that there most probably was 7 Jovian years plus a 27 year cessation. A real mother of all Maunders. Was this the reason for the Barbarian invasions at that time? Did they escape the terrible cold? And when the second cold spell came 200 years later, were also the Vandals attacking for the reason of the cold weather? Did the mighty Roman Army dwindle to nothing in just 20 years for this same reason?
There were 220 years between the Barbarian incursions from 230 AD to 270 AD and demise of the Roman Army after the Vandals from 450 AD to 490 AD.
Was it the warming of the climate that gave Diocletian and his followers the chance to revive The Roman Empire? There is one other historical moment whose simultaneous appearance gives this thought some credence. "The earliest inscriptions so far discovered in recognized Mayan lands are dated AD 292 and 320, dates on the threshold of the splendid Classic Period... The earliest date mentioned on inscriptions at Uaxactun is AD 328..." (Whitlock 1976). There is no known Columbus or other connector at that time between The Roman Empire and the Mayans.
Now it seems like this 100/200-year Maunder-like cyclity continued. The period of 200 years seems to oscillate between 180 and 220 years. The 220 is best approximated by 100+120 years and the 180 years by 60+120 years.
120 years of warm period passed. Then in 608 AD Euphrates froze. After the warm 700's, in 829 AD Nile froze (Cambridge CCNet 1998). The century of 800's belong to the dark ages. Again we have here 220 years.
"Another period of expansion [of the Mayas] extended from AD 731-90, when three splendid new centres were founded... Soon afterwards decline set in..." (Whitlock 1976)." "...the Maya of the Southern Lowlands, whose society underwent a rapid, dramatic, and justly famous collapse between about 790 and 890 AD." (Tainter 1988, pp. 152-153). "There is no trace of the large-scale destruction and fires which would have marked an invasion or an earth-quake." (Whitlock 1976, p. 26).
"The Norwegian farmer Folke Vilgerdson made the first attempt to settle in Iceland in about 865 AD... He lost his cattle in a severe winter and disappointed went back to Norway after having seen a fjord filled up by sea ice. Therefore he called the country Iceland. Only a few years later, in 874, Ingolf Arnason succeeded. He was followed by many others, and settlement was completed in 930 AD... In 982, Erik the Red discovered new land West of Iceland. He called it Greenland; according to the Greenlander Saga this was only to persuade people to follow him... But the O(18) curve suggests that the name described a reality... So the drastic climatic change [warming] late in the ninth century may be part of the reason why Iceland and Greenland did not get the opposite names." (Dansgaard: Palaeo-Climatic Studies on Ice Cores, in Oeschger, Messerli and Svilar, 1980).
"The beneficent times came to an end. Sea ice and stormier seas made the passages between Norway, Iceland and Greenland more difficult after AD 1200... In mainland Europe, disastrous harvests were experienced in the latter part of the thirteenth and in the early fourteenth century." (Grove 1988, pp. 1-2). The cold decades of 1680-1700 are very well documented, at least in Europe. (See for example Rothlisberger 1986). The glaciers in Alps increased, there was no good wine, harvests were a catastrophe and famine killed like the black death centuries before. Cold was also the decade of 1810-1820, including "the summer that did not come" or a "year without summer". The Tambora volcanic eruption has been accused for this summerless year 1816. Maybe it helped a little, but the cold spell had already begun from the spotless year 1810, with which Tambora had nothing to do.
If we take the Schove estimates of the maximum magnitudes (R(M)) from the period 1500-1750 and the measurements from 1750, we get (the rounding for exact centuries done only to make the general picture clear):
So the supercyclic rise is a very long process, maybe a 1000- or a 2000-cycle or even longer. The Sun seems to be much more irregular than we ever have imagined. The historical data seem to show that the 200-year oscillation has been there at least since 200 AD. The even centuries seem to be have been cold, odd ones warm, not to the accuracy of year, but in the average anyway. If a spotless sun during the third century caused the process of the Great Roman Empire demise to begin, we have to write the history books anew.
The other thing that seems apparent is that the general warming trend has been going on at least 1,800 years so that the third century AD may be the coldest century for at least 2000 years. Its only rival is the latter part of the 17th century. 1690's may have been almost as cold as the years 250 to 270. The cold periods later during the first millennium AD are more dramatical than the Little Ice Age thousand years later. On the other hand we may now live in the second mildest climate Anno Domini. Warmer periods seem to have occurred only from about 930 to 1200 AD with an interruption about 1030-1080. In mind the Roman Warm Period 1000 years earlier in mind, we may speculate that warm periods last about 350 years and really warm episodes don't exceed 100 years. Does this imply a sudden end to today's warm period in 2030-2050 (warming began in 1700, and the real warm period in 1930). This may even have greater implications to the whole Holocene climate study and possibly to ice age theories also. Considering the evidence it looks like a megalomaniac idea that the recent rise of half a degree would have been caused by man. So great are the natural variations. But man has always wanted to be in the center of the world.
One solar-based climate change may have a period of about 1050 years. There are many reports of a cold period beginning about 850BC (Geel et al.: Solar Forcing of Abrupt Climate Change around 850 Calendar Years BC), there begins around 200 AD a period of low cycles which transforms into a cold period around 230 AD (see above), consisting of a maximum length Gleissberg cycle and lastly the low periods beginning in 1200 AD (Schove) with an interruption in 1250-1280 leading to the rapid deterioration of the climate beginning about 1300 AD, which led to the end for the Medieval Maximum and for example to the demise of the Greenland habitat and forced Europeans to invent the warming system for their houses. The cold and warm period seems to have some 1000-1100 year oscillation.
More about Gleissberg cycle: click here
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