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CATEGORIES:Cambridge Centre for Climate Science
SUMMARY:CCfCS Lent Symposium: Time scales in Climate Scien
 ce. - Prof. David Beerling\, Dr. Pierre Dutrieux\,
  Dr. Dan Lunt
DTSTART;TZID=Europe/London:20130315T142000
DTEND;TZID=Europe/London:20130315T170000
UID:TALK43183AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/43183
DESCRIPTION:*UPDATED: Start & end time is now 2:20-5 pm*\n\nSc
 hedule:\n\nProf. David Beerling\, University of Sh
 effield.\n*The scientific case for avoiding danger
 ous climate change to protect future generations a
 nd nature.*\n\nThis contribution will consider the
  observational evidence for the effects of the hum
 an-\nmade imbalance in the Earth’s energy budget c
 aused by the global carbonization of society\nover
  the past century. It will show why drastic mitiga
 tion actions to curb greenhouse gas\nemissions are
  required if we are to restore the Earth’s energy 
 balance and avoid peak future warming of 2&deg\;C 
 and loss of planetary biodiversity.\n\nDr. Dan Lun
 t\, University of Bristol.\n*Warm climates of the 
 past - a lesson for the future?*\n\nThe relevance 
 of past climate research for future climate change
  is often cited as a motivation for palaeoclimate 
 research.  However\, what is the reality?\n\nThere
  is very strong evidence throughout Earth history\
 , over timescales from  thousands to millions of y
 ears\, that climate varies markedly\, and can do s
 o rapidly across key thresholds or when subjected 
 to particularly strong forcing.  Quantifying the c
 limate forcings and responses is more challenging.
   However\, past CO2 and temperature records can b
 e combined to produce constraints on climate sensi
 tivity\, providing full account is taken of uncert
 ainties in the forcing and response.  Synthesis of
  past environmental change can be used to evaluate
  numerical models. Inconsistencies between models 
 and data has been the stimulus to reassess both th
 e data (through better quantification of uncertain
 ties)\, and the models (through exploration of mod
 el sensitivities and experimental design)\, a proc
 ess which has led to improved agreement.  Indeed\,
  this model-data comparison can be used to provide
  quantitative constraints on future climate predic
 tions\, through a Bayesian approach.\n\nAlthough t
 here has been significant recent progress in this 
 field\, many challenges remain.  These include imp
 roved understanding and development of palaeo CO<s
 ub>2</sub> proxies\, developing of non-temperature
  proxies\, and integrating past climate test cases
  into the development cycle of climate models\n\nD
 r. Pierre Dutrieux\, British Antarctic Survey.\n*L
 arge spatial and temporal variability of oceanic m
 elting beneath the Pine Island ice shelf and impli
 cations for ice shelf-ocean interactions.*\n\nThin
 ning and acceleration of West Antarctic ice stream
 s are presently contributing about 10% of the obse
 rved global sea level rise⁠. A primary source is f
 rom Pine Island Glacier\, which has thinned since 
 at least 1992\, driven by changes in ocean heat tr
 ansport beneath its ice shelf and unpinning from a
  seabed ridge. Details about the ice-ocean interac
 tion driving this change\, however\, remain largel
 y elusive\, hampering our ability to predict the f
 uture behaviour of this and similar systems. Here\
 , high-resolution satellite and airborne observati
 ons of ice surface velocity and elevation are used
  to measure patterns of basal melt under the ice s
 helf and the associated adjustments to ice flow\, 
 revealing a complex distribution of oceanic meltin
 g at kilometre-scales. In addition\, ocean observa
 tions taken in austral summer 2012 show a 250-m lo
 wering of the thermocline at the glacier calving f
 ront and a 50% decrease of basal melting since 200
 9. High-resolution simulations of the ocean circul
 ation in the cavity beneath the floating glacier t
 ongue demonstrate that the seabed ridge blocks the
  warmest deep waters from reaching the ice and str
 ongly ties meltwater production to thermocline dep
 th above the ridge. These results highlight the ro
 le of climatic variability in glacial ice loss and
  the fundamental importance of local ice shelf and
  seabed geometry in determining the ice sheet resp
 onse.
LOCATION:Scott Polar Research Institute
CONTACT:Dr Alex Archibald
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