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Paul F. Hoffman visits the University of Bristol

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Paul F Hoffman of Harvard
On the 24th and 25th of September, Professor Paul F Hoffman of Harvard University (USA) kindly offered to visit the University of Bristol for two days. Fresh from fieldwork in Namibia, Paul agreed to give two talks: one upon Cryogenian glaciations and another upon the interaction of climate scientists and geologists.

Snowball Earth - Image from COSMOS
Paul is perhaps most well known for his part in the development of the Snowball Earth theory, suggesting that during the Cryogenian (850 to 635 million years ago) ice covered the entire globe, from the poles to the tropics. This theory is based upon multiple strands of evidence including palaeomagnetics, sedimentology, isotopic analysis and numerical modelling. Paul succinctly summarised these ideas while also discussing some new results published in Science two years ago. The authors of this paper suggest that during the breakup of Rodinia, a proterozoic supercontinent, the eruption of the Franklin Large Igneous Province (LIP) in Canada (716Ma) may have produced a climatic state more susceptible to glaciation. Although there have been many critics of Snowball Earth, it seems Paul remains loyal to the theory.  A wine reception was held afterwards within the School of Geography and allowed for further discussion amongst staff and students.

Paul gave a second talk on 25th September to a selection of PhDs and PDRAs who attend the Climate Journal Club (see below for details). Paul chose to give a more anecdotal, but nonetheless interesting, talk on the co-evolution of climate scientists and geologists during the last 250 years. His talk focused upon the development of a theory: from indifference to hysteria, followed by rejection and then finally acceptance. I asked him where Snowball Earth stands. He replied that it was somewhere in between hysteria and rejection!

Maybe in 50 years time we will know whether Paul was right all along...

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For more details, see the following references:

Hoffman, P.F., et al (1998) A neoproterozoic Snowball Earth. Science, 281, 1342
MacDonald, F.A., et al (2010) Calibrating the Crypogenian. Nature, 327, 1241

This blog was written by Gordon Inglis who runs the Climate Journal Club at the University of Bristol. 

For more details on attending the Climate Journal Club (bimonthly event designed to allow PhD and PDRAs to discuss a selection of climate-themed paper), please email Gordon.Inglis@bristol.ac.uk

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