BC3 Seminars: "Global past climate changes and their regional impact", Prof. Maria Fernanda...

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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

Transcript of BC3 Seminars: "Global past climate changes and their regional impact", Prof. Maria Fernanda...

Page 1: BC3 Seminars: "Global past climate changes and their regional impact", Prof. Maria Fernanda (2015-05-06)

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

Page 2: BC3 Seminars: "Global past climate changes and their regional impact", Prof. Maria Fernanda (2015-05-06)

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

Page 30: BC3 Seminars: "Global past climate changes and their regional impact", Prof. Maria Fernanda (2015-05-06)

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