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SUMMARY:Earth's Climate Evolution - Colin Summerhayes
DTSTART:20150228T193000Z
DTEND:20150228T210000Z
UID:TALK57541@talks.cam.ac.uk
CONTACT:Naomi
DESCRIPTION:Ice sheets are melting. "Global warming deniers are fond of sa
 ying "the climate is always changing". Well\, yes it is\, but why\, and ho
 w\, and how much? Studying the geological and ice core record helps us to 
 see how variable our climate is\, and what makes it so\, which helps to  e
 xplain what is happening now and what may happen next. The past 30 years h
 ave seen especially dramatic advances in our knowledge of past climatic va
 riability\, from studies of ice cores\, along with piston cores and drill 
 cores of marine sediment. A key emerging message is that our climate opera
 tes within a narrow natural envelope. Over the past 2000 years we have bee
 n at the cold end of the Holocene Neoglacial period\, driven there by chan
 ges in Earth's orbit. Peaks in solar output gave us the Medieval Warm Peri
 od and the warming from 1900 to 1945\, but since 1960 solar output has bee
 n flat or in decline\, while temperatures have gone on rising even though 
 the orbital data tell us we should still be in the cool Neoglacial. We hav
 e been driven outside the natural climate envelope by our emissions of CO2
 . This geologically based information is independent of numerical climate 
 models\, yet supports them. The rock and ice records tell us that further 
 increasing CO2 will drive up temperature and sea level.\n\nColin Summerhay
 es is a marine geochemist with expertise in determining past climates from
  the characteristics of marine sediments. He is an Emeritus Associate at t
 he Scott Polar Research Institute of the University of Cambridge. Formerly
  he was Executive Director of the International Council for Science's Scie
 ntific Committee on Antarctic Research (SCAR)\, Director of the Global Oce
 an Observing System (GOOS) Project at UNESCO's Intergovernmental Oceanogra
 phic Commission in Paris\, Director of the UK's Institute of Oceanographic
  Sciences Deacon Laboratory (Wormley)\, and Deputy Director of what is now
  the National Oceanography Centre. \n\nHis books include "Oceanography - a
 n Illustrated Guide"\, "Oceans 2020 - Science\, Trends and the Challenge o
 f Sustainability"\, "Antarctic climate Change and the Environment"\, and (
 in press) "Earth's Climate Evolution
LOCATION:SPRI Lecture Theatre\, Lensfield Road
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