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SUMMARY:Oxygen-isotope records of the Early Holocene climate of Europe - J
 onathan Holmes\, University College London
DTSTART:20171031T110000Z
DTEND:20171031T120000Z
UID:TALK94198@talks.cam.ac.uk
CONTACT:Max Holloway
DESCRIPTION:The transition from the late glacial interval to the early Hol
 ocene was characterized by abrupt warming in the northern hemisphere middl
 e and high latitudes broadly associated with a peak in orbitally-forced su
 mmer insolation. However\, palaeotemperature reconstructions from marine a
 nd terrestrial archives as well as modeling investigations indicate that t
 here were marked geographical variations in the timing of peak warmth asso
 ciated with the so-called Holocene Thermal Maximum (HTM). Remnant Laurenti
 de and Fennoscandian ice sheets\, which persisted into the mid Holocene\, 
 delayed the HTM until around 8 – 7.5 ka BP in some regions as a result o
 f albedo-sea ice feedbacks\, changes in atmospheric circulation\, and the 
 slowing of North Atlantic convection by meltwater. However\, despite previ
 ous attempts to characterize the nature of early to mid Holocene climate\,
  palaeoclimate data and modeling experiments do not always agree and the r
 elative importance of changes in temperature versus precipitation and the 
 extent of shifts in atmospheric circulation\, remain unclear. Oxygen-isoto
 pe values of precipitation are valuable tracers of past climate. We compil
 ed published and unpublished oxygen-isotope records from lacustrine and sp
 eleothem carbonates from across western and central Europe as a proxy for 
 the isotope composition of past precipitation\, in order to investigate ea
 rly to mid Holocene climate. We compare the geological data with results o
 f experiments with the isotope-enabled GCM HadCM3. Temporal and geographic
 al patterns show poor agreement with previous palaeotemperature reconstruc
 tions\, but are consistent with a change in atmospheric conditions in the 
 early to mid Holocene\, associated with a weakening of the westerly circul
 ation.
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 1
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