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Paleoclimatologia
Prof. Dr. Cristiano M. Chiessichiessi@usp.br
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
Marine sediment cores
Marine sediment cores
Giant piston corer (Calypso)
•Up to ~65m•No water depth limitation•Relatively complex operation•Medium to high efficiency (gaps)•Large diameter•Short ship time
Marine sediment cores
Marine sediment cores
Marine sediment cores
Drilling device (ship based)
•Hundreds of m•No water depth limitation•Highly complex operation•Medium to high efficiency•Small diameter•Long ship time
Marine sediment cores
Marine sediment cores
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
Marine sediment cores
Marine sediment cores
Marine sediment cores
Marine sediment cores
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
Mg/Ca in marine carbonates
Incorporation of Mg is exponentially related to
calcification temperature
Groeneveld and Chiessi (2011)
Mg/Ca in marine carbonates
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
Oxygen stable isotopes in marine carbonates
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
Oxygen stable isotopes in marine carbonates
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)
Oxygen stable isotopes in marine carbonates
Oxygen stable isotopes in marine carbonates
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
Oxygen stable isotopes in marine carbonates
Ravelo and Hillaire-Marcel (2007)
Surface vs. deep-watersRecent vs. LGM
Oxygen stable isotopes in marine carbonates
LeGrande and Schmidt (2006)
Local change in d18O: Salinity effect
Oxygen stable isotopes in marine carbonates
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 carbonates
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
Oxygen stable isotopes in marine carbonates
Very accurate analytical techniqueNow available at the Paleoceanography and Paleoclimatology
Laboratory (P2L) of the University of São Paulo
Oxygen stable isotopes in marine carbonates
Thermodynamic isotopic fractionation (aka
equilibrium fractionation):
Temperature effect
Mulitza et al. (2003)
Oxygen stable isotopes in marine carbonates
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)
Oxygen stable isotopes in marine carbonates
Oxygen stable isotopes in marine carbonates
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
Major elements in bulk marine sediments
Govin et al. (2012)
Non-destructiveHigh spatial resolution (mm)Al to BaQuick (4 hours for 1 m at 5 mm steps)
Major elements in bulk marine sediments
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
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
Sea surface temperature (oC, historical annual
mean)
Loca
rnin
i et
al.
(20
10)
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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)
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
SSTs reconstructed via Mg/Ca ratios in planktonic
foraminifera
Sediment trap calibration
Anand et al. (2003)
75 µm
Globigerinoides ruber
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
MATs reconstructed via branched glycerol dialkyl
glycerol tetraethers (GDGTs) analyses
Global soil calibration
Peterse et al. (2012)
Branched GDGTs
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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!
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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
Mg/Ca: Chiessi et al. (2015. Climate of the Past)
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?
d18O: Voigt et al. (2015. Paleoceanography)
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)
d18O: Voigt et al. (2015. Paleoceanography)
Chiessi et al. (2007), Voigt et al. (2015)
d18O: Voigt et al. (2015. Paleoceanography)
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
d18O: Voigt et al. (2015. Paleoceanography)
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)
d18O: Voigt et al. (2015. Paleoceanography)
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
Major elements: Stríkis et al. (2015. GRL)
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
Major elements: Stríkis et al. (2015. GRL)
Sea surface temperature (oC, historical annual
mean)
Loca
rnin
i et
al.
(20
10)
Major elements: Stríkis et al. (2015. GRL)
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
Major elements: Stríkis et al. (2015. GRL)
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)
Major elements: Stríkis et al. (2015. GRL)
Lapa Sem
Fim Cave
Paixão Cave
GeoB3910-2
Govin et al. (2012)
Major elements: Stríkis et al. (2015. GRL)
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)
Major elements: Stríkis et al. (2015. GRL)
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
Major elements: Stríkis et al. (2015. GRL)
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. Chiessichiessi@usp.br
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