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A Little Goes a Long Way: Researching Ash Clouds and Abrupt Climate Change

14 September 2016
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The Geological Society, Burlington House
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From the heights of the Greenland ice-sheet to the depths of the North Atlantic ocean, this talk presented how microscopic ash particles can help to identify the drivers of rapid climate changes during the last glacial period. Instantaneous deposition of geochemically distinct volcanic material over large geographical areas gives rise to a powerful dating and correlation tool called tephrochronology.

Although the foundations were set by the study of visible tephra horizons, the discovery of a few fine-grained ash particles, in sequences far-removed from volcanic centres, has revolutionised the scope of this technique. Some eruptions are now known to have deposited ash over 7000 km into regions not traditionally associated with tephra research.

The upshot of this is that just a few tiny particles have the potential to precisely correlate palaeoclimate records from the ice and sedimentary realms to address why climate changes abruptly.


Siwan Davies is a Professor in Physical Geography at Swansea University. Most of her research work is based on employing tephrochronology to constrain climate changes during the Quaternary period and the results also contribute to the reconstruction of eruptive histories.

She has worked on a range of geological archives including ice-cores, marine, lake and peat deposits. Her recent work has focused on the TRACE project (Tephra constraints on rapid climate changes), funded by the European Research Council.

Siwan was awarded the Philip Leverhulme Prize in Geography in 2011 and the Charles Lyell fund in 2013 and elected Fellow of the Learned Society of Wales in 2015. Siwan frequently contributes to public engagement activities in Welsh and English and is currently presenting a 5-part documentary series on climate change for S4C.


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