A bipolar perspective on past climate change

1. A bipolar perspective on pastclimatechange (and expectations for information from the Third Pole) Valérie Masson-Delmotte Laboratoire des Sciences du Climat et de l’Environnement (CEA-CNRS-UVSQ/IPSL) Gif-sur-Yvette, France 3rd TPE Workshop, Reykjavik, Iceland – August 2011

2. Whystudypastclimate change? Glacial-interglacial cycles Seasonal cycle • Expand the short instrumental records • Naturalclimatevariability • « Slow » components: ocean, carbon cycle, icesheets • Understand the response of climate to forcings Detection / attribution Climatefeedbacks Thresholds • Natural case studies to benchmark Earth System models Huybers and Curry, Nature, 2006

3. AIR Global atmospheric composition Firnificationprocesses Icecores ICE Local climate AEROSOLS Regionalatmosphericaerosol content: Seasalt, dust, volcanism, solaractivity, pollutants…

4. NEEM ? Deeppolar icecores NorthGRIP ~ 125 000 yrs EDML : 140 000 yrs EDC : 800 000 yrs European Project for IceCoring in Antarctica (EPICA)

5. The greening of Greenland Greenlandicesheet mass balance Masson-Delmotte et al, submitted; updates from Bhatt et al, 2010 and van den Broeke et al, 2009

6. Past, present and projected changes Orbital forcing Icecore perspective : the last 125 000 years Icecore perspective : the last 10 000 years Greenland cultures Instrumental data Projections (A1B) Masson-Delmotte et al, submitted; data from NGRIP, Nature 2004 and Vinther et al, Nature, 2009

7. Limited analogies betweenpast and future climate change 126 ka (orbital forcing) 2xCO2 IPSL climate model DJF JJA ann • Comparable magnitude of summerwarming and feedbacks atmid to high latitudes north • Major differences in low-high latitude temperature gradients and seasonality Masson-Delmotte et al, Clim Past, in press

8. Global impacts of Greenlandmelt in climate projections • global sealevel • Atlantic meridionaloverturning circulation • negativefeedback on Arcticwarming • ITCZ shifts with major impacts on monsoon • precipitation Masson-Delmotte et al, submitted; simulations fromSwingedouw et al, J. Climate, 2009 Masson-Delmotte et al, submitted; data from NGRIP, Nature 2004 and Vinther et al, Nature, 2009

9. The Greenland-Antarcticbipolarseesaw Precursors: dustfromChinesedeserts, Greenlandmoistureorigin shifts Full glacial conditions Glacial inception EPICA, Nature, 2006; Steffenson et al, Science, 2008; Capron et al, Clim. Past, 2010; Masson-Delmotte et al, PNAS, 2010

10. Bipolarseesawunderinterglacial conditions? Bipolarseesaw CO2 Antarctica T Antarcticmoisture source Asianmonsoon Methane N. Atlantic SST Greenland T Links between abrupt shifts in Antarcticmoistureorigin and monsoon Masson-Delmotte et al, PNAS, 2010 An Zhisheng et al, Science, 2011

11. New tools for new challenges Searching for the oldestice in Antarctica • Cause for the shift between 40 ky to 100 kyclimatic cycles ? • Oldestice challenge Interglacials +5°C Present-day -9°C Glacials Jouzel et al Science 2007, Loulergue et al Nature 2008, Lisiecki & RaymoPaleoceano2005 Masson-Delmotte et al, QSR, 2010; Jouzel and Masson-Delmotte, QSR, 2011

12. Towards a tri-polar perspective on climate change • Links between « northern pull », « southern push » and monsoon • Sequence of eventsbetweentropical,mid latitude and polar atmospheric circulation • Response of climate to major volcaniceruptions (importance for the decadalpredictability of climate) ChunmingShi et al, Clim. Past, submitted

13. Towards a tri-polar perspective on climate change • Exceptionalmonitoring effort for process-basedunderstanding of the climatic drivers of precipitationisotopiccomposition • Unique opportunity for a multi-archive TPE approach for reconstructingpastprecipitationd18O (icecores, tree rings, lakesediments, speleothems…) • Need of data synthesesfor benchmarkingclimatemodels • (CMIP5 includespaleoclimate simulations) Yao Tandong et al, in preparation