Surface water conditions in the Gulf of California during the Medieval Climate Anomaly and Little Ice Age
John Barron, Dave Bukry, Jason Addison - U.S. Geological Survey, MS 910, Menlo Park, CA 94025 (jbarron@usgs.gov, dbukry@usgs.gov, jaddison@usgs.gov)
Aug. 2005 ave. SST
Cave of the Bells
Ft. Huachuca Cave
200
400
600
800
1000 1200 1400 1600 1800 2000
Year (AD/CE)
Solar minima
70
40
30
D.
Maunder
Wolf
O. pulchra upwelling (productivity)
50
Oort
60
Dalton
Spörer
80
Monsoon
Peaks?
. aculeata
deep thermocline
D. stapedia subtropical, productive
20
10
La Niña vs El Niño - Winter SSTs
Winter
NW
nd
wi
s
MD022517
°C
background productivity
35
50
30
40
30
25
20
10
F. doliolus late winter-spring
0
Monsoon moisture spreads northward with warmer SSTs. Mitchell et al.
(2002 -J. Climate) found that monsoon rainfall in Arizona did not
occur until SSTs in the northern Gulf of California exceeded 26°C.
A. nodulifera tropical
production
200
400
600
Dalton
Maunder
Spörer
Oort
Wolf
Dalton
Maunder
Spörer
PCA 4
PCA Score
PCA Score
Wolf
Dalton
Maunder
Spörer
Wolf
Oort
Oort
-30
0
200
400
600
800
1000 1200 1400 1600 1800 2000
-40
0
200
400
600
800
0
200
400
600
Year
Enhanced productivity in the east during
solar minima. Limited correlation in the
west.
PCA 5
30.5
1.7
-40
1000 1200 1400 1600 1800 2000
800
-40
1000 1200 1400 1600 1800 2000
200
400
600
800
1000 1200 1400 1600 1800 2000
Year
Year
Reduced input of tropical, oligotrophic waters
during the MCA in the east. Enhanced input
during the LIA and prior to ~AD 700.
Enhanced input of deep thermocline North
Pacific waters during MCA and the past 200
years in the east. Low productivity periods.
Opposite east-west trends in subtopical
water influx between east and west with
reversal occuring AD 1300-1500.
0
summer
stratified
-0.171
0.07
-0.003
-0.219
0.009
0.381
-0.001
0.003
-0.08
-0.061
0.509
0.293
0.022
0.018
0.032
-0.118
-0.007
-0.043
0.216
0.064
0.057
-0.008
-0.009
-0.563
0.004
-0.155
0.026
0
0.158
0.061
-0.01
-0.552
-0.013
0.249
0.001
0.006
-0.248
-0.034
0.181
-0.07
-0.007
-0.018
0.069
-0.115
0.373
0.018
0.01
-0.06
0.055
-0.08
-0.047
0.562
-0.048
-0.108
-0.036
0
PCA 1 diatom -positive = Fragilariopsis doliolus
(Production associated with influx
, of subtropical
waters); negative = Thalassionema nitzschioides
(other production)’(explains 56% of the variance)
Md2517PCA
80
MCA
60
40
PCA 2 diatom -positive = Fragilariopsis doliolus
(subtropical production), negative =
Cyclotella
(explains 28.2% of the variance)
BAMsilicoPCA
BAM80PCA
LIA
Md2517PCA
60
solar minima
MCA
PCA 3 diatoms -positive = Azpeitia nodulifera
(tropical, oligotrophic), negative Cyclotella
(explains 3.5% of the variance)
BAMsilicoPCA
BAM80PCA
LIA
30
solar minima
40
Md2517PCA
MCA
20
BAMsilicoPCA
LIA
BAM80PCA
solar minima
+1σ
+1σ
PCA 4 diatoms - positive = Cyclotella (warm summer,
Thalassiosira oestrupii
(oceanic, subtropical) (explains 3.4% of the variance)
Md2517PCA
20
MCA
10
+1σ
BAMsilicoPCA
BAM80PCA
LIA
solar minima
20
20
0
-20
-1σ
10
0
-1σ
+1σ
0
0
-1σ
-10
-20
-1σ
-40
-60
-80
-10
-40
0
200
400
600
800
1000 1200 1400 1600 1800 2000
Year
-60
0
Proportion of diatom production
associated with late winter-spring
increased after ~AD 850?
200
400
600
800
1000 1200 1400 1600 1800 2000
Year
Variable late winter-spring productivity
during the MCA, increased east-west
gradient during the LIA. PCA 2 has a
robust correlation wiith diatoms/gram
in MD02-2517 (R =0.74553, n = 39)
-20
-20
0 200
400
600
800
1000 1200 1400 1600 1800 2000
Year
Variable summer input of tropical
oligotrohpic waters, antiphase east-west?
Interpreted as warm ENSO events by
Sancetta (1995, Paleoc.10, 67-84) in the
eastern Guyamas Basin.
-30
0
200
400
600
800
1000 1200 1400 1600
1800 2000
Year
Warm, summer stratified waters generally
reduced during the MCA. Strong eastwest contrast during recent.
Conclusions and Future Directions
20
0
http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowser.jsp
40
T. nitzschioides
60
Extreme El Niño
tropical
BAM80 E-17 Diatoms
70
Lluch-Cota et al., 2010, Prog. Oceaogr. 87, 114-126)
Extreme La Niña
D. perlaevis
0
-30
Dalton
LIA
-0.032
-0.015
0.005
0.049
0.008
0.781
-0.005
-0.015
-0.02
0.009
-0.594
-0.02
-0.08
0.019
-0.05
-0.025
-0.084
0.023
0.021
0.079
0.042
0.037
0.038
-0.025
0.023
0.055
-0.005
0
-20
-1σ
Maunder
MCA
90
-0.035
-0.068
-0.002
-0.228
-0.001
-0.295
-0.003
-0.009
-0.17
-0.059
-0.418
0.761
-0.034
-0.031
-0.015
0.004
0.044
0.003
0.248
-0.004
0.001
-0.017
0.021
0.036
0.02
-0.025
-0.017
-0.009
D. perlaevis
-10
Spörer
BAM80 E17 chronology, varve counting & radiocarbon, Robert
Karlin, 1984, PhD dissertation, Oregon State Univerisity
0.023
0.019
0.001
0.047
-0.004
0.117
0.003
0.001
0.073
0.008
0.105
0.423
0.013
0.004
0.001
-0.027
0.017
0.001
-0.885
0.016
0.015
0.014
0.004
0.035
-0.004
-0.021
0.002
0.003
0
Wolf
Eastern Guaymas Basin
Variable
Actinocyclus curvatulus
Actinocyclus octonarius
Actinocyclus octonarius var.
Actinoptychus spp.
Alveus marina
Azpeitia nodulifer
Azpeitia tabularis
Bidulphia alternans
Coscinodiscus radiatus
Coscinodiscus spp. (large)
Cyclotella spp.
Fragilariopsis doliola
Hemiiscus cuneiformis
Paralia sulcata
Rhizosolenia bergonii
Rhizosolenia spp.
Roperia tesselata
Stephanopyxis spp.
Thalassionema nitzschioides
Thalassiosira eccentrica
Planktoniella sol
T. leptopus
T. simonsenii
T. oestrupii
T. spp.
Thalassiothrix spp.
Benthics
other
solar minima
Oort
Year (AD/CE)
LIA
+1σ
-20
PCA Score
800 1000 1200 1400 1600 1800 2000
0
Dalton
600
10
Maunder
tropical
10
Spörer
400
Eigenvalues
% Variance
PCA 4
62.6
3.4
20
Wolf
200
-60
Diatom PCAs
PCA 2
PCA 3
516
64.5
28.2
3.5
summer
subtropcial productivity oligotrophic,
?
tropical
input
MCA
30
20
BAMsilicoPCA
BAMsilicoPCA
-20
Year
PCA 1
1.03E+03
65.1
D. aff. aculeata
MD2517silicoPCA
40
solar minima
Oort
0
-40
PCA Score
A. nodulifera
during solar minima
LIA
-10
0
Dalton
1 x108
-20
Maunder
late winter-spring production
10
% of Assemblage
MD02-2517
0
2 x108
F. doliolus
20
% Biogenic Silica (BAM80-E17)
Dalton
Maunder
Spörer
Wolf
Oort
2x108
0
30
Monsoon
Peaks?
8
4x108
3
40
x108
Strong east-west gradient
-80
Declines in diatom productivity at ~AD 1200 and ~AD 1500
MCA = cold or increased upwelling, LIA= warm or decreased upwelling;
8x108
West
4 x108
50
solar minima
East
6x10
background productivity
LIA
MCA
BAM80
warming
T. nitzschioides
0
20
Spörer
Barron & Bukry (2007, Mar. Micr. 62: 115-139) suggest % biogenic
silica peaks in BAM80 E-17 coincide with solar minima.
Hypothesis -Surface water conditions BAM80 E-17 driven by NW
winds in winter-early spring. Higher values of % biogenic silica =
dominance of winter over summer conditions.
60
5 x108
20
BAMsilicoPCA
BAMsilicoPCA
MCA
30
40
O. pulchra
MD2517silicoPCA
40
Wolf
% of Assemblage
(Biogenic silica studies for MD02-2517 in progress)
MD02-2517 Diatoms
40
LIA
Oort
0
tropical
60
-0.011
-0.073
-0.446
-0.09
0.097
-0.879
-0.072
-0.033
-0.017
BAMsilicoPCA
BAMsilicoPCA
solar minima
60
PCA Score
D. perlaevis
MCA
D. stapedia
80
PCA Score
deep thermocline
10
Biogenic Silica & Diatoms/gram
. aculeata
-0.562
0.031
0.02
0.015
0.816
0.074
0.088
0.062
-0.018
80
Dalton
D.
0.811
0.054
0.041
0.084
0.54
0.003
0.182
-0.068
0.022
MD2517silicoPCA
solar minima
Maunder
20
-0.074
-0.018
-0.012
0.012
-0.164
-0.098
0.934
0.292
0.002
LIA
Dalton
30
0.114
0.03
0.019
0.014
0.037
-0.024
-0.283
0.95
0.002
100
BAMsilicoPCA
BAMsilicoPCA
MCA
Maunder
upwelling (productivity)
MD2517silicoPCA
Dictyocha perlaevis
(tropical, oligotrophic) -explains 1.5% of the variance)
D. perlaevis
(tropical, oligotrophic) -explains 3.1% of the variance
(explains 6.8% of the variance)
Spörer
40
Variable
D.aff. aculeata
D. ampliata
D.calida calida
D.franshepardii
D. perlaevis total
D.stapedia (Large)
D.stapedia total
O. pulchra total
others
PCA 5
9.43
0.3
Wolf
O. pulchra
70
10x108
Monsoon
Peaks?
PCA 3
PCA 4
101
49.2
3.1
1.5
deep
thermocline oligotrophic,
productivity subtropical N. Pacific
tropical
Oort
50
# diatoms per gram
% of Assemblage
Winter and early spring biologic productivity are higher in the
eastern Guyamas Basin than in the west, due to stronger
northwest winds than blow down the eastern side of the Gulf.
60
PCA 2
220
6.8
Spörer
Eigenvalues
% Variance
PCA 1
2.83E+03
87.7
Wolf
D. stapedia subtropical, productive
70
BAM80
°C
LIA
- positive =Dictyocha stapedia
-influx of subtropical prodcutive water, SSTs >20°C
-positive = Octactis pulchra
-winter-early spring productivity/upwelling,
SSTs <20° (explains 87.7% of the variance)
Silicoflagellate PCAs
% Biogenic silica
Jan. 2006 ave. SST
MCA
80
% of Assemblage
Winter is dominated by strong NW winds that
induce upwelling, cooler SSTs, diatom blooms.
Summer -relaxation of winds, northward
advection of tropical waters.
Western Guaymas Basin
MD02-2517 chronology, varve counting,
Heather Cheshire, 2012, University Coleege London
Diatoms per gram ( MD02-2517)
East-West surface water differences in the Guaymas Basin during the past
2000 years can be explained by analogy to the modern climatology.
Presently, winter upwelling and biologic productivity are stronger in the east
than they are in the west. At the same time, northward flowing surface
currents that transport tropical waters into the Gulf during the summer are
stronger in the east than they are in the west. These east-west differences
appear to have been especially pronounced during the MCA.
Principal Component Analysis by Scott Starratt (on combined silicoflagellate and diatom downcore data)
Oort
High-resolution analyses of diatoms, silicoflagellates, and percent opal in
laminated sediment cores from the Guaymas Basin (central Gulf of California)
reveal pronounced changes in surface water conditions over the past 2000
years. Prior to ~ AD 1200, surface waters in the western Guaymas Basin
(boxcore MD02-2517c2 at 27.4850° N, 112.0743°W, water depth 887 m) were
characterized by high biologic productivity marked by alternating relative
abundances of the diatoms Thalassionema nitzschioides and Fragilariopsis
doliolus and the silicoflagellates Octactis pulchra and Dictyocha stapedia.
Following the early part of the Medieval Climate Anomaly (MCA; ~AD 9001200), productivity declined abruptly in two steps (at ~AD 1200 and ~1500).
These shifts were marked by increases in the relative abundance of tropical
diatoms (Azpeitia nodulifera) and silicoflagellates (Dictyocha perlaevis). The
western Guaymas record thus resembles that of the eastern North Pacific
(equatorial Pacific and Santa Barbara Basin) with a cooler La Niña-like MCA
followed by a warmer El Niño-like Little Ice Age (LIA; ~AD 1350-1850).
In contrast, in the eastern Guaymas Basin (Kasten Core BAM80 E-17 at 27.920°
N, 111.610°W, 620 m of water depth), highly productive conditions dominated
the past 2000 years until a post ~ AD 1800 period of surface water warming,
which has been documented throughout the Gulf. Unlike the surface waters
to the west, the MCA (~ AD 800-1200) in the east is distinguished by a decline
in biosiliceous productiviy proxies and an increase in tropical taxa. These
findings are suggestive of warmer MCA surface water conditions that are
conducive to enhanced transport of monsoonal moisture northward up the
axis of the Gulf.
Silicoflagellates & Diatoms
Western vs Eastern Records
PCA Score
Abstract
PCA Score
science for a changing world
15
800 1000 1200 1400 1600 1800 2000
Year (AD/CE)
Limited Proxy Monsoon Records of past 2,000 years
Studies of diatoms, silicoflagellates, and biogenic opal in the Guaymas
Basin reveal that biosiliceous productivity/upwelling was always higher
in the in the eastern part of the basin than in the west during the past
2000 years.
Detailed proxy precipitation records are limited for western region of the
North American Monsoon. Cave speleothem isotope records from Arizona
are largely conflicting. Monsoon precipitation relationships with Gulf
diatom and silicoflagellate records are presently unclear.
In the west, biosiliceous productivity declined abruptly in two steps (at
~AD 1200 and ~1500). These declines coincided with increases in the
relative abundance of tropical diatoms and silicoflagellates, suggesting
that the climate record resembles that of the eastern North Pacific
(equatorial Pacific and Santa Barbara Basin) with a cooler La Niña-like
early MCA followed by a warmer El Niño-like LIA (AD 1350-1850).
Studies presently underway on western core MD02-2517 will refine surface
water interpretations
• Inorganic geochemistry, Jason Addison, USGS
• % biogenic opal, Jason Addison, USGS
• Alkenone SST & organic geochemisty, Erin McClymont,
Durham University, UK
• Isotopic studies and diatom-hosted trace metals, Raja Ganeshram,
University of Edinburgh, UK
Arizona Speleothem Records as Monsoon Proxies -Treube, S.A., et al., 2012, Heterogeneity
Stronger in the east
Gulf SST Hypotheses
Gulf SSTs of the past 300 years reflect El Niños
- Herguera et al., 2003, Geofís. Internacional,
23(3), 397-406
Gulf SSTs of the past 300 years display a steady 2°C
warming that reflects solar irradiance and increases
in greenhouse gases
-Goñi et al., 2001, Geochim. et Cosmochim. Acta
65(4), 545-557
Monsoon Peaks
in both?
δ18O per mil VPDB
Late Winter-Spring Upwelling and
Biologic Productivity
of speleothem records of North American monsoon rainfall: Cave or climate? Poster GC33D-1050,
Amer. Geophys. Union, Fall Mtg.
Increased
monsoon rain
Ft. Huachuca Cave
(Ault et al., 2001)
Cave of the Bells
Increased
winter rain
-50
450
950
Year (AD/CE)
1450
1950
In the east, peaks in biosiliceous productivity coincide closely with solar
minima, suggesting an intensification of NW winds lead to increased
upwelling. The MCA (~AD 900-1200) and the most recent 200 years are
marked by decreased biosiliceous productivity and increased
representation of tropical taxa.
Detailed studies in the eastern Guaymas Basin are planned for the future.