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Paleoclimatologia

Prof. Dr. Cristiano M. [email protected]

Interdisciplinary Climate Investigation CenterUniversity of São Paulo

Programa

Neste módulo serão apresentados os principais métodos analíticos e arquivos geológicos utilizados em pesquisas paleoclimáticas e paleoceanográficas nas seguintes escalas de tempo:

Orbital Milenar Multidecadal

Estes tópicos serão apresentados com base em estudos feitos por pesquisadores do INCLINE, além de outros colhidos na literatura.

Programa

... (multidecadal natural climate variability) may be underrepresented in many models, but needs to be recognized in

adaptation planning. Natural fluctuations are big enough to overwhelm the steady background warming at any point in time.

Suggested reading

Ruddiman, W.F. 2006. Earth's Climate: Past and Future. 2nd edition. W.H. Freeman, New York, 388pp.

Sifeddine, A., Chiessi, C.M., Cruz, F.W., et al,, 2014. Informações paleoclimáticas brasileiras. In: Ambrizzi, T., Araujo, M. (Orgs.). Base científica das mudanças climáticas. Contribuição do Grupo de Trabalho 1 do Painel Brasileiro de Mudanças Climáticas ao Primeiro Relatório da Avaliação Nacional sobre Mudanças Climáticas. 1ed.Rio de Janeiro: COPPE, v. 1, p. 126-180.

Vimeaux, F.; Sylvestre,F.; Khodry, M. (eds.) 2008. Past Climate Variability from the Last Glacial Maximum to the Holocene in South America and Surrounding Regions: Developments in Paleoenvironmental Research. Springer-Verlag, Berlin, 418pp.

Outline

•Marine sediment cores

•Some methods applied in paleoceanography

• Mg/Ca in marine carbonates (temperature)

• Oxygen stable isotopes in marine carbonates (salinity

and other features)

• Major elements in bulk marine sediments (continental

input)

•Case studies

Marine sediment cores

Gravity corer

•Up to ~24m•No water depth limitation•“Easy” operation •High efficiency•Large diameter•Short ship time


Giant piston corer (Calypso)

•Up to ~65m•No water depth limitation•Relatively complex operation•Medium to high efficiency (gaps)•Large diameter•Short ship time


Drilling device (ship based)

•Hundreds of m•No water depth limitation•Highly complex operation•Medium to high efficiency•Small diameter•Long ship time


Drilling device (in situ)

•Up to 70 m•Operation between 200 and 2000m•Medium to high complex operation•Medium to high efficiency•Small diameter•Long ship time


Some methods used

•Collecting marine sediment cores

•Autochtonous and alloctonous sediments

•Oxygen stable isotopes in marine carbonates

•Carbon stable isotopes in marine carbonates

Some methods applied in paleoceanography

Some methods applied in paleoceanography

Ruddiman (2006)

Mg/Ca in marine carbonates

Factors that influence Mg/Ca in marine carbonates

1. Calcification temperature

2. Salinity

3. Carbonate ion concentration

100 µm


Incorporation of Mg is exponentially related to

calcification temperature

Groeneveld and Chiessi (2011)


Detailed cleaning procedure

Oxygen stable isotopes in marine carbonates

Factors that influence d18O in marine carbonates

1. Calcification temperature

2. Sea water d18O – global sea water d18O and local sea water d18O


Difference in vapor pressure: H216O evaporates more readily that

H218O and H2

18O condenses more readily than H216O

Water vapor is depleted in 18O (in relation to seawater) and rain droplets are enriched in 18O (in relation to water vapor)

Cloud water vapor becomes increasingly depleted in 18O with increase in latitude and altitude

Rayleigh distillation process


During glacials, 16O is concentrated in glaciers leaving the oceans enriched in 18O

Ruddiman (2006)

Oxygen stable isotopes in marine carbonatesFa

cto

rs t

hat

infl

ue

nce

d1

8O

of

seaw

ate

r

Global change in d18O: Ice-volume

effect

Adkins et al., (2002)

Lambeck and Chappell (2001)



Continental ice is depleted in 18O (in relation to seawater)

For a LGM 130m drop in sea level and a 1‰ change in mean ocean d18O: 0.08‰/-10m sea level


Ravelo and Hillaire-Marcel (2007)

Surface vs. deep-watersRecent vs. LGM


LeGrande and Schmidt (2006)

Local change in d18O: Salinity effect


LeGrande and Schmidt (2006)

EvaporationPrecipitationFluvial discharge (including water from continental ice)

Salinity and d18Osw: highly correlatedIn the sea surface: 0.5‰/1.0psuHigh latitudes are strongly influenced by excess precipitation (and vice-versa)

d18O = 0.46 * S – 16.05

r2 = 0.95

Salinity [psu]

34

d1

8O

sw

[‰

VS

MO

W]

34.5 35 35.5 36 36.5

-0.4

0

0.4

0.8

1.2

Conkright et al. (2002), LeGrande and Schmidt (2006)

SW + SACW + AAIW


Oxygen stable isotopes in marine carbonatesFa

cto

rs t

hat

infl

ue

nce

d1

8O

of

seaw

ate

r

Mixture with water masses of different composition

100 µm


Very accurate analytical techniqueNow available at the Paleoceanography and Paleoclimatology

Laboratory (P2L) of the University of São Paulo


Thermodynamic isotopic fractionation (aka

equilibrium fractionation):

Temperature effect

Mulitza et al. (2003)


In many species of foraminifera, shell calcite is in oxygen isotopic equilibrium with seawater

Isotopic separation factor between calcite and seawater is inversely correlated to calcification T: ~0.22‰ for 1oC

If d18Osw is known, d18Oc can be used as a paleothermometer

T [oC] = 16.9 – 4.38 (d18Ocalcite - d18Oseawater) + 0.1 (d18Ocalcite - d18Oseawater)2

Shackleton (1974) equation

d18O seawater conversion from VPDB to VSMOW (Hut, 1987)

d18Oseawater [VSMOW] = d18Oseawater [VPDB] + 0.27

Correção para variações no volume continental de gelo (Lambeck

and Chappell, 2001; Schrag et al., 2002)

d18Oivc seawater [VSMOW] = d18Oseawater [VSMOW] – (sealevel * 1 / 130)



Ravelo and Hillaire-Marcel (2007)

Major elements in bulk marine sediments

Factors that influence major elements in bulk marine sediments

1. Continental vs. marine input

2. Sediment source

3. Continental weathering

Ca: typically marine carbonatesFe, Al, Si, Ti and K: typically continental sediments


Govin et al. (2012)

Non-destructiveHigh spatial resolution (mm)Al to BaQuick (4 hours for 1 m at 5 mm steps)


Outline

•Marine sediment cores

•Some methods applied in paleoceanography

• Mg/Ca in marine carbonates (temperature)

• Oxygen stable isotopes in marine carbonates (salinity

and other features)

• Major elements in bulk marine sediments (continental

input)

•Case studies

1) Mg/Ca: Chiessi et al. (2015. Climate of the Past)

2) d18O: Voigt et al. (2015. Paleoceanography)

3) Major elements: Stríkis et al. (2015. Geophysical Research Letters)

Case studies

AAIW

AABW

Salinity [psu]0

1000

2000

De

pth

[m

]

3000

4000

5000

37

36.5

36

35.5

35

34.540oS 20oS EQ 20oN 40oN 60oN

Conkright et al. (2002)

Atlantic meridional overturning circulation (AMOC)

NADW

Mg/Ca: Chiessi et al. (2015. Climate of the Past)

1Sv = 106 m3 s-1EQ

60oS

60oN

0o60oW Ganachaud and Wunsch (2000),Schmid et al. (2000), Lutjeharms (2006)

16

13 4

Shallow

Deep

Bottom

Upwelling

Downwelling

15

10

6

16

23

6

10


EQ

60oS

60oN

0o60oW

1PW = 1015 W

Itaipu generates 0,000014 PW

(14 GW)

Ganachaud and Wunsch (2000)

0.3

1.3

Large influence

over global

climate


Sea surface temperature (oC, historical annual

mean)

Loca

rnin

i et

al.

(20

10)



Maier-Reimer et al. (1990), Crowley (2011)

It has been suggested that the BC might redirect the excess heat to the South Atlantic during times of AMOC slowdown

Available records lack the necessary temporal resolution!

Is there a direct relationship between the strength of the AMOC and SST of the BC on millennial time-scale?

Carlson et al. (2008)

Heinrich Stadial 1 (and Termination 1) is probably the best example of an AMOC slowdown event


Continental slope (influence of the BC)Age model based on 9 AMS 14CSedimentation rates 160-10 cm kyr-1

Temporal resolution 10-120 yr

GeoB6211-2

33oS/50oW/657m

Chiessi et al. (2008), Razik et al. (2013), Chiessi et al. (2015)


SSTs reconstructed via Mg/Ca ratios in planktonic

foraminifera

Sediment trap calibration

Anand et al. (2003)

75 µm

Globigerinoides ruber


MATs reconstructed via branched glycerol dialkyl

glycerol tetraethers (GDGTs) analyses

Global soil calibration

Peterse et al. (2012)

Branched GDGTs


Chiessi et al. (2015)

SST: high during HS1 and low during the YDMAT: two-step increase (second half of HS1 and during the YD)

MAT lags SST!


Bard et al. (2000), Barker et al. (2009), Chiessi et al. (2015), McManus et al. (2004), Shakun et al. (2012), Weldeab et al. (2006)

• In-phase thermal evolution of the BC and the NBC during HS1 and the BA, but an opposite behavior during the YD

• Similar changes in SST in the eastern South Atlantic

Bush et al. (2004), Chiessi et al. (2015), EPICA Com. Mem. (2006), Monnin et al. (2004), Shakun et al. (2012)

• Changes in MAT are remarkably synchronous with atmospheric CO2 rise

Denton et al. (2010)

South American monsoon

strengthens

South Atlantic warms up

South America warms up


d18O: Voigt et al. (2015. Paleoceanography)

Lumpkin and Garzoli (2011)

It has been suggested that the BMC undergone a recent (1992–2007)

southward shift of ca. 0.8° per decade as a direct response to a southward shift in

the maximum of the wind stress curl across the South Atlantic basin

associated with a weakening of the northern portion of the SWW

But how to disentangle natural multidecadal variability from anthropic effects?


Lumpkin and Garzoli (2011)

Continental slope (influence of the BC and MC)Age model based on 31 AMS 14CSedimentation rates 80-10 cm kyr-1

Temporal resolution 50-90 yr

Chiessi et al. (2007), Kalnay et al. (1996), Peterson and Stramma (1991), Voigt et al. (2015)


Chiessi et al. (2007), Voigt et al. (2015)


100 µm

Globorotalia inflata

Voigt et al. (2015)

Gradual southward shift of the SWW 1–1.5° from the earlyto mid-Holocene

Millennial-scale SWW variability (ca. 1°) with no longer-term trend


He et al. (2011), Liu et al. (2009), Voigt et al. (2015)

• Proxy-inferred and modeled SWW shifts compare qualitatively

• Model underestimates both orbitally forced multi-millennial and internal millennial SWW variability by almost an order of magnitude

Bond et al. (2001), Voigt et al. (2015)


Correlation to IRD deposition in the high latitudes of the North Atlantic suggest an interhemispheric coupling

AAIW

AABW

Salinity [psu]0

1000

2000

De

pth

[m

]

3000

4000

5000

37

36.5

36

35.5

35

34.540oS 20oS EQ 20oN 40oN 60oN

Conkright et al. (2002)

Atlantic meridional overturning circulation (AMOC)

NADW

Major elements: Stríkis et al. (2015. GRL)

1Sv = 106 m3 s-1EQ

60oS

60oN

0o60oW Ganachaud and Wunsch (2000),Schmid et al. (2000), Lutjeharms (2006)

16

13 4

Shallow

Deep

Bottom

Upwelling

Downwelling

15

10

6

16

23

6

10


EQ

60oS

60oN

0o60oW

1PW = 1015 W

Itaipu generates 0,000014 PW

(14 GW)

Ganachaud and Wunsch (2000)

0.3

1.3

Large influence

over global

climate


Sea surface temperature (oC, historical annual

mean)

Loca

rnin

i et

al.

(20

10)


How precipitation over NE Brazil responded to Heinrich Stadial 1?

Kageyama et al. (2013)

Heinrich Stadial 1 (and Termination 1) is probably the best example of an AMOC slowdown event


Continental slope (influence of the NBC) and NE Brazil

Age model based on AMS 14C (marine core) and U/Th (stalagmites)

Stríkis et al. (2015)


Lapa Sem

Fim Cave

Paixão Cave

GeoB3910-2

Govin et al. (2012)


Ca: typically marine carbonatesTi: typically continental sediments

Ti/Ca is a proxy for the input of siliciclastic sediments vs. marine carbonates

Continental runoff and precipitation

Stríkis et al. (2015)

Increased precipitation during HS1

Two events of widespread increase in precipitation (HS1a and HS1c), separated by a dry excursion (HS1b)


Swings in precipitation over NE Brazil correlate with changes in IRD input to the North Atlantic

Rapid reorganization of atmospheric circulation in response to variations in ocean heat transport


Bard et al. (2000), Jaeschke et al. (2007), Stríkis et al. (2015), Thouveny et al. (2000), Wang et al. (2001) , Zhang et al. (2014)

Many thanks for your attention!

Interdisciplinary Climate Investigation CenterUniversity of São Paulo

Prof. Dr. Cristiano M. [email protected]

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