In this instance, the cat as in catastrophism – sky fairies and all that. We are back to 536AD and the sky darkening across Europe (and elsewhere) as a thick dust cloud rolled in and stayed overhead for some 18 months. Procopius said the Sun shone as dimly as the Moon (which is very low energy) which caused summer frosts and summer snow falls. Crops and fruit failed to ripen. Three years later a similar dust veil blocked out sunlight several months and famine presaged the Great Plague of Justinian which is said to have wiped out a third of the population in parts of Europe. Whole territories were decimated – virtually depopulated. Barbarians quickly filled the vacuum (or that is how it is often presented). See www.telegraph.co.uk/news/science/science-news/11726459/Did-american-volc…
Scientists have determined (8th July) that the cause was 'probably' a series of North American volcanoes which shot large amounts of sulphate and ash into the atmosphere, followed by further eruptions in the tropics. Why so many volcanoes might have blown in a short space of time is not questioned – and why civilisation in Persia, China and India were likewise decimated at the same time is also not questioned (it must be volcanoes, it can't be cosmic).
The appears to be the reason why Mike Baillie changed his mind and accepted the second event during 536-541AD low growth tree ring event was also driven by a volcano (see the debate at http://cosmictusk.com earlier in the year). He had relied on there being no volcano in ice cores dateable to 539/540AD – as opposed to 536AD ((it was a double whammy). In the end he had no reason not to accept a second bout of volcanic activity as he had already accepted the first incident. It seems that ice cores were looked at more closely and it was decided, using historical records as their guide, that there was a volcanic signature for the second event – and scientists had been mistaken in the first instance. The British Antarctic Survey took part in the research and Nottingham University, as well as 17 other institutions and universities across Europe. The research therefore has a Eurocentric focus – but relied on North American volcanoes to do the deed (and undisclosed tropical volcanoes may also have played a part). Quite why they say the ruined crops, drought and famine sparked the bubonic plague is less clear but perhaps it involved a weakened immune system. This bit appears to be a bit of a tag on to the research – how do you define a link between a dust veil event and an outbreak of plague (unless you consider the former had an extraterrestrial origin). They can't avoid the plague, we may note, as it dominated the historical literature to a greater extent than the dust cloud (or whatever kind of cloud it might have been).
It is reckoned that 15 out of the 16 coldest summers recorded between 500 and 1000AD followed large volcanoes (or volcanic signatures in ice cores). The information is derived from 20 individual ice cores extracted from ice sheets in Greenland and Antarctica. It then admits ice core timescales had been misdated by 5 to 10 years (as Baillie has for years banged on about) – but why were they misinterpreted. Was it convenient to redate them? What if the historical record has 10 to 15 years missing as deduced by Steve Mitchell (the divergence in history between Rome and Constantinople/ Alexandria). How actually did they decide the ice cores were faulty – was it an exercise to close an anomaly as pointed out and utilised by Baillie? We also know there was an awful lot of tectonic activity in the 30 years or so surrounding the 536-41AD low growth tree ring event – major earthquakes that flattened cities like Antioch and caused massive tsunami waves to sweep across the Eastern Mediterranean. Is there any chance all this activity was joined up, earthquakes, volcanoes, and strange goings on in the sky.
We may also wonder now that volcanoes are back in the basket if perhaps a relook at David Key's book, 'Catastrophe: an investigation into the origins of the modern world' might be in the offing. No counting on it.