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Ice Ages … a different way of looking at them

9 December 2012

Well, perhaps not so different as this paper might be nearly 20 years old, but interesting as Steve Mitchell in his 2004 SIS talk on sea levels around Britain in the Late Roman period toyed with the idea the land had subsided – but can the crust of the Earth move up and down? Well, we have a Swedish scientist that seems to think it can. Nils-Axel Morner, on the Ice Ages and why they might have been kickstarted around 3 million years ago – see http://tallbloke.wordpress.com/2012/12/08/nils-axel-morner-neotectonics-… The paper can be seen at http://tallbloke.files.wordpress.com/2012/12/nb-a-mc3b6rner-the-new-glob… and apart from being another spiffing post by Tall Bloke we get a hint of big changes happening shortly before the Ice Ages hit the geochronological monitor.

Nils-Axel Morner is well past retirement age and that is why this is probably an oldish paper. He has, over the last few years, consistently criticised IPCC projections on sea levels, and CAGW supporters have targeted him repeatedly as they really don't like what he says. This is notionally that sea levels are historically low and unlikely to rise in the near future – which gets the alarmist camp even more agitated, with puffed cheeks palpitating and spitting chunks of – excitable dribble. So far, he has been proved right as sea levels are remarkably unimpressive, a rise in millimetres rather than inches – and certainly no sign yet of the measures in feet that are shrilly repeated by people that know little about the subject. The latter day Noah's can shout and scream as much as they like but people have had enough of it all … and picking on scientists that don't sing to the same songsheet will in the end be counter-productive. However, in this paper Nils-Axel Morner is not interested in global warming or rapidly approaching rising sea levels that will drown major cities, so much so all their citizens will have to take obligatory swimming lessons in order to get from point A to point B. In this paper the subject is Ice Ages – but funny enough sea levels play a role. That is after all his specialist subject. Now, why the Ice Ages should have come into being at around 3 million years ago is the subject of some controversy as the Milankovitch theory does not really have the push that led to shove to start it all off – so people look around for something to nudge the Earth into an Ice Age and one favourite idea is that ocean currents are periodically blocked or diverted, and tectonic activity and mountain building led to major geological changes. The culprit, as far as Plate Tectonics theory is concerned, is firmly placed in the camp of the African plate moving and pushing against the Eurasian plate and causing uplift of the continental crust. In this paper it is not just Africa trying to move in a northerly direction but various other parts of the world also display evidence of tectonic activity and uplift. The raising of the continental crust, it goes, led to lower global temperatures, but what caught my eye was the claim this occurred in tandem with a 'general lowering of the ocean floor due to an adjustment of the geoid-oceanid level'. Well, knock me down with a feather but this implies the crust can go down as well as up – which was the general thrust of what Steve Mitchell was saying in his talk, the iffy bit if fyou like. The term neotectonics was coined by Merscherikov in 1968 and used by Rhodes Fairbridge in 1981 and was also used to denote crustal movements during the Neogene and Quaternary periods (from the Miocene onwards). Morner uses it to denote Upper Cenozoic young and on-going tectonics (in 1989 for example). The first of the Chinese loess deposits began around 2.5 million years ago which coincides with the new tectonic regimen in the Mediterranean region.

What we appear to have is a succession of catastrophic events, cause unknown – but might they involve axial movement and therefore readjustments of the geoid and the oceans, the tectonics being a part of the event but not necessarily the whole story.

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