Dust levels in the Little Ice Age

23 May 2012

At http://tallbloke.wordpress.com/2012/05/23/dust-deposition-in-the-aral-se… … Tall Bloke's Talkshop continues to raise some very interesting issues, going to subjects other blogs do not venture, or avoid. In this post, Tim Channon looks at a paper in Quaternary Science Reviews at www.sciencedirect.com/science/article/pii/S0277379111002903.html which was published in volume 30 issue 25-26, in 2011. The reseach concerns mineral aerosol and dust deposition in the Aral Sea in the last couple of thousand years, basically by taking sediment cores and comparing them with other proxy data bases. Deposition was high during the Little Ice Age, between ad1400 and 1780, indicating there was a lot of dust in the atmosphere being moved around in pressure systems and by winds. In contrast, during the Roman Warm Period, ad1-350, when we might expect there had been clear skies, the deposition was very low – described as 'remarkably' low. Dust loads increased quite a bit between ad350-720 and slowed down again, with a few jumps in the 8th and 9th centuries. However, in general the period between ad720-1400, which includes the Medieval Warm Period, dust deposition was low. Again, in recent years, especially since the 1940s, dust deposition has again been low. Variations in dust deposition, in the paper, are attributed to changes in the Siberian High and mean atmospheric temperature of the northern hemisphere. We may also note, independent of the paper's conclusion, this discovery is not inconsistent with the Clube and Napier model in which the Late Roman Period (after 350ad) and the Little Ice Age coincided with the Earth traversing a dusty region of space. Commentary at the end of the piece, following the charts, is interesting in so far as Channon says several other papers in the last couple of years have also looked at how airborne particles affect weather processes – and this includes particles with an extra terrestrial origin. Tall Bloke, in response, asked what elements are thought to be ET?

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