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SUMMARY:A geological perspective on climate change: forcings\, feedbacks a
 nd tipping points. - Dr Luke Skinner\, University of Cambridge\, Departmen
 t of Earth Science
DTSTART:20111124T161500Z
DTEND:20111124T173000Z
UID:TALK33895@talks.cam.ac.uk
CONTACT:Dr Alex Archibald
DESCRIPTION:Humanity is currently conducting an unprecedented climate expe
 riment\, the outcome of which is typically framed in terms of an equilibri
 um ‘climate sensitivity’. This term encapsulates the impact on global 
 average temperature of an imposed energy budget imbalance and its associat
 ed feedbacks\; it is a calibration of climate response to forcing. Althoug
 h our current climate experiment is unprecedented in its origin\, it will 
 not be the first time that global climate has changed drastically in assoc
 iation with a carbon cycle perturbation. Indeed\, in seeking observational
  constraints on climate sensitivity and the fundamental ‘ground rules’
  of climate adjustment\, much may be learned from the geological record of
  past climate change. This talk will explore two key aspects of the climat
 e system that are emphatically underlined in the palaeoclimate record. The
  first is the importance of positive feedbacks that act to amplify relativ
 ely subtle perturbations to the earth’s energy budget\, broadly as predi
 cted by numerical models. The second is the context (i.e. climate) depende
 nce of these positive feedbacks. Together\, these two aspects of the clima
 te system provide the necessary ingredients for the emergence of non-linea
 r behaviour\, or ‘tipping points’. What we see is a climate system who
 se resilience to perturbations depends sensitively on the history of previ
 ous perturbations. This could pose a significant challenge for accurate lo
 ng-term climate prediction.
LOCATION:Pfizer  Lecture Theatre\,  Department of Chemistry
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