At https://phys.org/print446394010.html … ancient rainfall records stretching back 550,000 years into the past show a monsoon pattern closely in step with the Ice Ages. The article is in the journal Science (May 25th 2018). During the northern hemisphere summer the tropics and sub-tropics north of the equator warm while the tropics and sub-tropics south of the equator cool. The Asian monsoon season brings rainfall to about a half of the world's population -between April and September. Over tens of thousands of years the changes in the intensity of the summer monsoon appears to correspond to the waxing and waning of the polar ice caps. The researchers suggest these changes in the monsoon actually drives global changes in wind and ocean currents in ways that afffected whether the polar ice caps grew or shrank. The new findings will be utilised in updates to climate models.
However, there are always two ways of looking at anything, and most obvious can be stood up on its head. The above idea can be switched around fairly easily and we say it is the waxing and waning of the polar ice caps that are influencing the monsoons (the opposite interpretation). In other words, a growing polar area will push down on the temperate zone, squeezing it territorially and in doing so exerting pressure on the sub tropices – and shifting the monsoon rains to the south. What might cause the polar region to expand at the expense of the temperature zone? Milankovitch solved that in the early 20th century – reduced sunlight. One might argue this was due to orbital changes (as adopted in the uniformitarian model) or one might argue it was due to how much dust and aerosols were in the atmosphere. The Younger Dryas period, for example, is noted for the amount of dust in the atmosphere. The astrophysicist, Sir Fred Hoyle, even suggested an asteroid or comet fragment impacted into the ocean and caused a massive amount of water to rise into the atmosphere and clear it (hence the steep rise in temperature at the end of the YD period). One might also argue that the Younger Dryas was a period when the earth wobbled at the axis of rotation and when it had eventually stabilised, returning to the point it started at, the temperatures resumed to what they had been prior to the event (whatever it was that kicked it off). Others might assume a period of low solar activity – for extended periods coinciding with Ice Ages (or cooling events). There is not a lot of enthusiasm for that idea – but it should not be dismissed as the sun is a variable star (as they say). Whatever, we might want to look at where the 550,000 year record comes from. It is derived from a hill of soil near Xi'an in China – actually a hill of loess. Loess is laid down in layers – by the wind. That is the mainstream point of view. Loess in other parts of the world is very often located along river valleys (such as Brentford in west London, on the side of the Thames) or along former river valleys (or terrace formations). It is just as likely that loess has an origin as a water borne soil – but in China the loess deposits are huge. They wqould have to have been laid down very quickly if water borne in origin – in a flood situation (not uncommon in Chinese history) or by even more dramatic ways – such as the oceans invading the land during pole shift (that idea that is positively frowned on by mainstream). Hence, from a catastrophist point of view it is not altogether trustworthy to think of loess as a record of slow accumulation (especially as layers are divided by the bones of extinct animals that could likewise have been sloshed around and smashed during a watery demise event). Even if we accept that Ice Ages are a reality the date of 550,000 years ago only embraces a few of these events – which would include the Anglian ice sheet advance in Britain which was the furthest south any of them came, at around 450,000 years ago. The odd thing about the ice ages is that prior to Agassiz and his theory the Pleistocene did not exist. It was inserted into the geological chronology column simply in order to accommodate the ice age theory – and Agassiz did not think in terms of the multitude of ice ages that is currently the mainstream position. It was thought there was just four of them at one time. The layer cake of loess is thousands of feet thick and represents an interesting archive of the past – uniformitarian or catastrophist. it was clearly not all laid down in a single event – but we may assume that a series of events is a feasible explanation rather than swallowing the idea if accumulated very slowly at a given rate. The researchers took sample at 5cm intervals on the basis 5cn was said to represent 500 years of accumulation. This by itself suggests their whole line of enquiry is awry but they did have to comply with mainstream thinking otherwise they would not have been taken seriously by the establishment geology fraternity. The also used beryllium 10 to provide a proxy for precipitation because when it rains dust is washed out of the atmosphere as particles that add substance to the pile of loess. Hence, reality may have a foot in both camps – the addition of atmospheric dust to water borne loess (in catastrophic events). The reality also is they used uniformitarian analysis of loess formation in order to produce a marraige with the uniformitarian ice age theory. Is that circular reasoning – going round and round to keep the uniformitarian model alive and kicking. The reality therefore is that if you accept the mainstream explanation for the origin of loess (wind and rain) it is possible to accept this finding – but if you are somewhat queasy about the mainstream view of loess formation (and its connections with rivers, such as the Yellow River in China, named after the quantify of loess it carries down to the sea) you might take the actual dates involved with a pinch of salt. A foot in both camps seems to be one position to take – otherwise known as sitting on the fence.