bc3 seminars: "global past climate changes and their regional impact", prof. maria...
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BC3 seminars:Prof. Maria Fernanda Sanchez -Goñi, 6th of May
Global past climate changes and their regional impact
Maria Fernanda Sanchez Goñi Ecole Pratique des Hautes Etudes UMR CNRS-EPOC 5805, University of Bordeaux
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Interglacial
Last Glacial Maximum
From W.F. Ruddiman, 2001
Geological archive δ18O marine record
MIS5
MIS4 MIS3
MIS2 MIS1
MIS = Marine Isotope Stage
MIS7
MIS9
MIS11
MIS13
MIS15
Insolation
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Eccentricity: shape of the Earth’s trajectory around the Sun Obliquity: tilt of the Earth’s axis (seasonality) Precession: wobbling motion of the Earth (seasonality magnitude)
Eccentricity
Obliquity
Precession
Insolation
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From
W.F
. Rud
dim
an, 2
001
δ18O marine record
Geological archives
MIS5
MIS4 MIS3
MIS2 MIS1
Insolation
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• GI characterised by different amplitude and duration • Largest temperature changes at D-O 19, 16-17, 12 and 8 • Some GS include Heinrich events (H)
H1 H2 H3 H4 H5 H6
MIS 1 MIS 2 MIS 3 MIS 4 MIS 5
D-O
16-17
Dansgaard-Oeschger (D-O) cycles Cyclicity: 1,000-2,000 years (Dansgaard et al., 1984)
H1 H2 H3 H4 H5 H6
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Heinrich events and Heinrich stadials Cyclicity : 7,000-10,000 years (Heinrich, 1988)
Ruddiman belt
Outside Ruddiman belt
Sanchez Goñi & Harrison, QSR, 2010
(Ruddiman, 2001)
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Iceberg discharges
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Global impact of abrupt climate changes
Ahn & Brook, Science, 2008
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Abrupt climate change
Change that takes place more rapidly than the underlying forcing. (Alley et al., 2002)
However, as forcing is a priori unknown, abrupt change is defined as the combination of magnitude of the change and the rapidity with which is
accomplished. (McManus et al., 1999; Martrat et al., 2004 SSTannual > 0.26°C/100 years)
Change that takes place in less than 200 years and in magnitude exceeds the decadal variability typical of the interval in which it occurs.
(Sanchez Goñi & Harrison, 2010)
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Climate impact on the different Earth’s reservoirs and feedback processes
D-O cycles &
Heinrich events
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Understanding the origin and mechanisms of any given climate change needs the knowledge of the response (nature and timing) of the
different Earth’s reservoirs, and for that we need a common chronology.
Climate impact on the different Earth’s reservoirs and feedback processes
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M. quanta
Pinus
46µm²(TL)
Foraminifères
Dinoflagellés
G. bulloides
N. pachyderma (s)
IRD > 250 µ Uvigerina
IRD Pollen
Microcharbon
Possible time-lags between the different Earth’s reservoirs in response to a given climate change
Direct comparison approach: pollen in marine sediments
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cold
warm
Herbs
Pioneer
Forest
cold warm Herbs
Pioneer
Forest
warm cold
Is vegetation in equilibrium with rapid climate change? or
Is there a time-lag between climatic change and vegetation response?
« Dynamic equilibrium » « Disequilibrium hypothesis »
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Dansgaard-Oeschger variability and Heinrich events
Outstanding questions:
•Regional expression of D-O and H events
•Climatic processes
•Interaction with other forcings (e.g. orbital parameters, ice volume)
Heinrich events
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Winter
Summer
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Eurosiberian region
Mediterranean region
MD99-2331 MD03-2697 MD01-2447
MD04-2845
MD95-2042 SU81-18 MD95-2043
International Programme
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Sanchez Goñi et al., QSR, 2008
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Mediterranean forest Pine
Evergreen oak
Olive tree
Semi-desert vegetation
Sagebrush Ephedra Chenopods
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Fletcher & Sanchez Goñi,QR, in press
Fletcher & Sanchez Goñi,QR, 2008
8 12
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MD99-2331
Sanchez Goñi et al., QSR, 2008
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Sanc
hez
Goñi
et
al.,
QSR
, 200
8
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D-O 8
H4
D-O 8
H4
MD99-2331
MD04-2845
MD95-2042
MD95-2043
Sanchez Goñi et al., QSR, 2008
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12°C
18°C
Temperate forest
* Synchroneity between SST and vegetation changes in western Europe in response to the millennial-scale climatic variability * The impact of the D-O climatic variability on western European ecosystems is spatially variable
modified after Van Campo, 1984
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Pearson correlation coefficient = 0.755
Methane & Climate
Sanchez Goñi et al., QSR, 2008
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www.physicalgeography.net/fundamentals/7p.html.
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Vegetation Response to Millennial-scale Variability during the Last Glacial (2010)
M.F. Sanchez Goñi & S. P. Harrison
Contributors:
P. G. Bartlein, A.-L Daniau, L. Dupont, W. Fletcher, R. Hayashi, I. Hessler, Y. Igarashi, G. Jiménez-Moreno, S. van der Kaars, M. Kageyama, P. Kershaw, M.P. Ledru, A. Paul, H. Takahara,
C. L. Whitlock, E. Wolff
D. Magri, V. Margari, U. Müller B. Huntley, J. R. M. Allen, R. Cheddadi, N. Combourieu-Nebout, F. Naughton, E. Novenko,
K. Roucoux, P.C. Tzedakis, R. S. Anderson, S. Desprat, L. D. Grigg, E. C. Grimm, L. E. Heusser, B. F. Jacobs, C. López-Martínez, D. A. Willard, F. Kumon, S. Kawai,
M. Yamamoto, T. Irino, T. Oba, J. Chappellaz, D. Roche
QUEST Working Group on Abrupt Climate Changes
QUEST-DESIRE Dynamics of the Earth System and the Ice-core Record
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D-O 8 warming (38 ka) ΔT =14°C in Greenland, high CH4
Harrison, Sanchez Goñi, QSR, 2010
Temperature Precipitation
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Rapid, ~100 years, and synchronous vegetation/atmosphere response in western Europe to SST changes and D-O cycles. Freshwater input is associated with strong forest reduction Contrasting latitudinal impact of D-O variability modulated by orbital parameters: below 40°N (Mediterranean region): strong D-O 17-16 (~60 ka) et D-O 8 (~38 ka) above 40°N strong D-O 14 (~52 ka) et D-O 12 (~45 ka) Strong link between the Mediterranean climate and Asian monsoon
Conclusions 1
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Rapid ice sheet growth in the North Atlantic high latitudes at the MIS 5a/4 transition
Ice volume
MIS 5
MIS 4
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The last interglacial-glacial transition (~80-70 kyrs BP)
C20 C19 C18’
D-O21 D-O20 D-O19
Ice volume changes Millennial-scale variability
Cooling Warming
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• Do data confirm model predictions and, in particular, the warm sea – cold land thermal gradient at the time of ice growth?
• How this orbitally-controlled ice growth is affected by the sub-orbital climatic variability, i.e. Dansgaard-Oeschger (D-O) cycles
and Heinrich events?
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At orbital scale
cold land warm sea
Sanchez Goñi et al., Nat. Geosci., 2013
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At sub-orbital scale
C20 C19 C18’
Warm surface currents
Moisture transport
Icebergs
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Sanchez Goñi et al., Nat. Geosci., 2013
At sub-orbital scale
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Conclusions 2
• Our data provide strong evidence for a rapid ice growth scenario involving both orbital and sub-orbital increases of air-sea thermal contrast at the MIS 5a/4 transition
• A warm pool in the western European margin during the North Atlantic cold events of the MIS5a/4 transition, C20, C19 and C18’.
• The tight coupling between marine and terrestrial responses to the millennial-scale cycles is not a pervasive feature throughout the Quaternary in the western European margin as previously thought
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EPHE laboratory Paleoclimatology and Marine Paleoenvironments