BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:CCfCS Lent Symposium: Time scales in Climate Science. - Prof. Davi d Beerling\, Dr. Pierre Dutrieux\, Dr. Dan Lunt DTSTART:20130315T142000Z DTEND:20130315T170000Z UID:TALK43183@talks.cam.ac.uk CONTACT:Dr Alex Archibald DESCRIPTION:*UPDATED: Start & end time is now 2:20-5 pm*\n\nSchedule:\n\nP rof. David Beerling\, University of Sheffield.\n*The scientific case for a voiding dangerous climate change to protect future generations and nature. *\n\nThis contribution will consider the observational evidence for the ef fects of the human-\nmade imbalance in the Earth’s energy budget caused by the global carbonization of society\nover the past century. It will sho w why drastic mitigation actions to curb greenhouse gas\nemissions are req uired if we are to restore the Earth’s energy balance and avoid peak fut ure warming of 2°\;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 chan ge is often cited as a motivation for palaeoclimate research. However\, w hat is the reality?\n\nThere is very strong evidence throughout Earth hist ory\, over timescales from thousands to millions of years\, that climate varies markedly\, and can do so rapidly across key thresholds or when subj ected to particularly strong forcing. Quantifying the climate forcings an d responses is more challenging. However\, past CO2 and temperature recor ds can be combined to produce constraints on climate sensitivity\, providi ng full account is taken of uncertainties in the forcing and response. Sy nthesis of past environmental change can be used to evaluate numerical mod els. Inconsistencies between models and data has been the stimulus to reas sess both the data (through better quantification of uncertainties)\, and the models (through exploration of model sensitivities and experimental de sign)\, a process which has led to improved agreement. Indeed\, this mode l-data comparison can be used to provide quantitative constraints on futur e climate predictions\, through a Bayesian approach.\n\nAlthough there has been significant recent progress in this field\, many challenges remain. These include improved understanding and development of palaeo CO2 proxies\, developing of non-temperature proxies\, and integrating pas t climate test cases into the development cycle of climate models\n\nDr. P ierre Dutrieux\, British Antarctic Survey.\n*Large spatial and temporal va riability of oceanic melting beneath the Pine Island ice shelf and implica tions for ice shelf-ocean interactions.*\n\nThinning and acceleration of W est Antarctic ice streams are presently contributing about 10% of the obse rved global sea level rise⁠. A primary source is from Pine Island Glacie r\, which has thinned since at least 1992\, driven by changes in ocean hea t transport beneath its ice shelf and unpinning from a seabed ridge. Detai ls about the ice-ocean interaction driving this change\, however\, remain largely elusive\, hampering our ability to predict the future behaviour of this and similar systems. Here\, high-resolution satellite and airborne o bservations of ice surface velocity and elevation are used to measure patt erns of basal melt under the ice shelf and the associated adjustments to i ce flow\, revealing a complex distribution of oceanic melting at kilometre -scales. In addition\, ocean observations taken in austral summer 2012 sho w a 250-m lowering of the thermocline at the glacier calving front and a 5 0% decrease of basal melting since 2009. High-resolution simulations of th e ocean circulation in the cavity beneath the floating glacier tongue demo nstrate that the seabed ridge blocks the warmest deep waters from reaching the ice and strongly ties meltwater production to thermocline depth above the ridge. These results highlight the role of climatic variability in gl acial ice loss and the fundamental importance of local ice shelf and seabe d geometry in determining the ice sheet response. LOCATION:Scott Polar Research Institute END:VEVENT END:VCALENDAR