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SUMMARY:The birth\, death and reincarnation of Snowball Earth - Professor 
 Ian Fairchild
DTSTART:20210308T170000Z
DTEND:20210308T180000Z
UID:TALK156466@talks.cam.ac.uk
CONTACT:James Craig
DESCRIPTION:Snowball Earth provides a wonderful case history of the comple
 x ways in which science advances. A data-driven\, somewhat inductive under
 standing of widespread Neoproterozoic glaciation was championed by Cambrid
 ge’s Brian Harland in the 1960s and he later facilitated relevant work i
 n Svalbard and Greenland by Hambrey and Fairchild. Then in the late 1990s\
 , the model-driven Snowball Earth theory exploded on the scene\, becoming 
 vigorously championed by Paul Hoffman and linked to his unrivalled field e
 xperience. The theory encouraged hypothesis-testing which guided some subs
 equent developments. The aspects of the theory that still stand are that g
 laciations were necessarily prolonged (millions of years in duration) and 
 synchronous\, that a hydrological hiatus associated with a deep-frozen sta
 te is associated with an unconformity\, that atmospheric PCO¬2 became ver
 y high during glaciation and the associated glacial sediments were deposit
 ed during the final stages of the panglaciation.  The events immediately f
 ollowing deglaciation are still hotly disputed. Neoproterozoic glaciation 
 and associated carbonates will be illustrated with field\, petrological an
 d geochemical data\, mainly from Svalbard and Scotland. The research that 
 has resulted from the stimulus of Snowball theory is salutary in warning u
 s that extreme climate states\, inimical to human civilization\, have occu
 rred in the past\, and hence that there are dangers in the use of technolo
 gy\, such as shielding the sun with aerosols\, to fix our current climate 
 crisis. 
LOCATION:The talk will be held virtually over zoom. The link will be circu
 lated to members via email\, while non-members may contact jac293@cam.ac.u
 k for details
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