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The 8.2 ky cooling episode

13 September 2023
Catastrophism, Climate change, Geology

Ther 8.2 ky event, or 6200 to 6000BC – another way of saying the same thing. If you want to find out about it, and read lots of articles, then all you have to do is put the event into your search engine. At https://en.wikipedia.org/wiki/Bond_event … we have another slant on what is basically the same thing. They are discernible as North Atlantic ice raft events and these are tentatively linked to climate fluctuations, including during the Holocene [the last ten thousand years]. Some 8 of them are currently recognised in that period. They were originally paced at 1500 year intervals. Fred Singer and Dennis Avery  even wrote a book, ‘Unstoppable Global Warming: every 1500 years‘ Roman and Littlefield:2007. Fred Singer was in fact a strident critic of global warming, as it then was, and I suppose he saw modern warming as a manifestation of one of the Bond events and nothing to do with co2. Nowadays, the 1500  year cycle has been put to bed and advocates now talk in terms of 1000 year intervals. Actually, if you go back and look at the cold blips featured in tree rings and ice cores, especially in the second half of the Holocene, there are a lot more events than the Bond hypothesis would allow. Cycles, in any case, can be an artifact of computer modeling.

Gerard Bond was the lead author, in 1997, of a research paper that postulated a cycle of 1470 years in the Late Pleistocene and Holocene. It was mainly based on petrologic tracers of drift ice in the North Atlantic, a novel piece of research that appears to have impressed a lot of people. Bond and his team drew attention to these cold blips and looked around for an explanation. As catastrophism was out of the question as it would have designated the research as fringe or plain barmy, they  decided on a more terrestrial based solution to the puzzle. Hence, we have this idea of the Atlantic overturning cycle – as if it can just overturn without a vector causing that to happen. Bond specifically saw a connection with the Sun – a solar cycle of some kind. If they had looked at the Clube and Napier theory of the break-up of a large comet, or Centaur object, they could have explained the 1500 year cycle during the Late Holocene and the more frequent cycle later on, including what is a much more frequent ambivalance of cold blips after 6200BC.  Unfortunately for Bond and his pals, recent work has set out to bomb their argument. The new argument is that it was in all probability a statistical artifact. Following the publication of the North GRIP Greenland ice core chronology in 2005, it became clear Dansgaard-Oeschger events also show no such pattern. However, in spite of that the North Atlantic ice rafting events do seem to coincide with low lake levels in some parts of the US, and weak monsoons. Something was clearly going on. These cool periods also appear to correspond with aridification in the Levant and Middle East. This confirms the link to weak monsoons – or a switch in the monsoon track.

I’ve never been able to re-create the 1500 year cycle – even using Fred Singer’s data. There are just too many cooling events in tree rings and ice cores. No wonder it was decided it was a statistical nightmare. The wiki provides a list of such events, but why they chose these ones over others is difficult to understand. At the outset it should be said the 6200BC event is proably the most statistically likely of them all. It resembles a short version of a dryas event, for exmple, and roughly 5000 years separates it from the outset of the Younger Dryas, at one end, and the Piorra cooling event around 3000BC, at the other end. 3 x 1500 years = 1450, rather than 5000 years. No doubt their arithmetic involved other key points – the end of the Younger Dryas perhaps, rather than the beginning of it. We also have to rely on mainstream dating methodology. This is the one factor that probably makes it most unworkable.

Presumably, if the Younger Dryas event represents an encounter with a newly formed meteor flux from a comet that was in the process of breaking up, one could work through the cold blips that lasted for a significant period of time, much longer than what we would expect if a big volcano had gone off, then we might explain the cycle in a different way. There are also a lot of double whammys, as one might describe them. For example, in the Roman period we have cooling events and problems in the 3rd and 6th centuries AD, which are repeated in the Late Bronze upheavals by about the same interval, and in the second half of the 3rd millennium BC as well. The earth therefore passed through the Taurid stream in question twice, on its orbit through space, and then not again for around a thousand years or so.

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