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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.
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| 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
