SUPPLEMENTARY INFORMATION
doi: 10.1038/ngeo707
Supplementary Materials
Wagner, J. D., J. E. Cole*, J. W. Beck, P. J. Patchett, G. M. Henderson, and H.R. Barnett, 2010.
Moisture variability in the southwestern US linked to abrupt glacial climate change, Nature
Geosciences.
* = corresponding author
Note – Supplemental figures are cited in order based on their citation in the paper.
A. Supplementary Methods
Field sampling and site characteristics:
We recovered this sample (COB-01-02) in July 2001, from the Cave of the Bells, Santa Cruz
County, AZ (31°45'N, 110°45'W). The cave lies at shallow depths beneath a small topographic
high; modern cave activity results from water that falls as precipitation and not from older
circulating groundwaters. Over a 16-month period, the cave temperature averaged 19.2 ± 0.1 °C
with no seasonal cycle, consistent with mean local temperatures and a small geothermal offset as
documented in nearby caves 1.
Core handling and geochemical analyses:
After removal from the cave, the stalagmite was cored with a 2.5cm drill bit and two slabs
were taken from the core center. We used a drilled core for all sampling so that the stalagmite
could be capped and returned to the cave, in accordance with our U.S. Forest Service agreement.
One core slab was sectioned into 4-6 mm increments for U-Th dating using thermal ionization
mass spectrometry (TIMS). The other slab was sampled for stable isotope analysis at 100 µm
increments with a micromill along the growth axis, and for additional higher-resolution U-Th
dating with a diamond-impregnated wire saw (1.5-3mm increments). A photo of the core slab
used for isotopic analysis is shown in Supplementary Figure 3.
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U/Th methods and age-model development
U/Th dating was performed using three different analytical facilities as indicated in
Supplementary Table 1. All preparation was done under clean lab conditions at the University of
Arizona. We used decay constants from Cheng et al. 2000 2 and corrected for initial Th assuming
an estimated value for 230Th/232Th activity of 0.8 ± 50%; such age corrections were on the order
of decades. TIMS analyses were performed at the University of Arizona 3 and multicollector
inductively-coupled mass spectrometry (MC-ICP-MS) at Arizona and Oxford University 4
(Supplementary Table 1). All ages are reported as years before 1950 (years BP). U/Th data are
plotted against depth in Supplementary Figure 4. Two hiatuses were identified at ~3.5mm and
~27mm depths, based on the presence of cloudy bands (0.6 and 1.3mm thin, respectively) and
substantial reduction of growth rates. The age model was constructed separately for the section
below the lower hiatus and the section between the two hiatuses. We did not attempt to provide
an age model for stable isotope data above the uppermost hiatus, because no U/Th dates were
derived exclusively from material above that cloudy band. Between the two hiatuses, we used a
third-order polynomial to fit age-depth data pairs. Below the 27mm hiatus, we used a spline fit,
which tracked the age-depth data more closely than a polynomial.
Stable isotope methods
We analyzed oxygen and carbon isotopes on a dual inlet stable isotope mass spectrometer
(Micromass Optima) with an automated carbonate preparation system at University of Arizona.
Analytical precision on δ18O and δ13C measurements is better than 0.08‰ and 0.04‰ (1σ),
respectively. These data are presented in Supplementary Table 2 and will be placed on file at the
World Data Center for Paleoclimatology (www.ncdc.noaa.gov/~paleo). X-ray diffraction
analysis on portions of the stalagmite indicated a calcite composition with no aragonite present.
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supplementary information
To improve estimates of regional climate change from our isotopic record, we corrected the
speleothem δ18O for the global effect of ice volume on water vapor using a marine sedimentderived estimate 5. We calibrated the radiocarbon-based age model of the sediment core to
absolute ages using the online tool at http://radiocarbon.ldeo.columbia.edu/ and linearly
interpolated between data points to obtain correction values for each of our depths.
Isotopic equilibrium considerations:
We selected this sample from deep in the cave to avoid disequilibrium effects on the stable
isotope record. The classic “Hendy test,” which assesses correlation between contemporaneous
δ18O and δ13C from samples along a growth band 6, is inappropriate for this sample due to its
slow growth rate and rapid isotopic changes. A recent assessment suggests that disequilibrium
can be detected using time-transgressive analysis of δ18O-δ13C covariation7; we explored such
covariation for various time intervals and did not observe a strong correlation that would indicate
disequilibrium (Supplementary Figure 5). Ongoing cave monitoring will help constrain the
degree of disequilibrium present and the degree to which we can use equilibrium calculations to
infer modern calcite values.
B. Supplementary Discussion
Modern isotope systematics
To constrain interpretations of speleothem δ18O, we present data on dripwater and
precipitation δ18O. Analysis of 20 years of modern precipitation isotopic data from Tucson
(Supplementary Figure 1) shows that the relationship between precipitation δ18O and
temperature is weak for both winter and summer 8. However, we observe a significant inverse
relationship between precipitation δ18O and precipitation amount for both winter and summer,
with a stronger relationship in summer (significant at 98% and 99.99%, respectively). We
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doi: 10.1038/ngeo707
analyze the seasons separately because their sources and dynamics are very different. Winter
precipitation δ18O is lower than that in summer by about 4‰.
Within the cave, isotopic measurements on drip water collected monthly since late 2003 yield
an average value of -9.56±0.29‰. This value is consistent with winter (October-March)
precipitation values (Supplementary Figure 2), in Tucson 8,9, even though about half of the
annual precipitation arrives during the summer monsoon (July-September). Summer
precipitation provides little infiltration into the cave because it is intense, localized, and cooccurs with very high temperature and vegetation heat stress 10. We see isotopic evidence of
summer precipitation in the dripwater values only during monsoons that are unusually strong;
even then, the perturbation is small (<1‰) and/or short-lived (a few months). The cave dripwater
values are also consistent with the composition of winter rainwater collected at the cave,
although that record is shorter and noisier.
Based on these results, we interpret the century-millennium scale variations in our
speleothem δ18O record as relative indicators of winter moisture, which is governed by the
position of the westerly storm track11,12. The influence of temperature on this time scale is likely
small; any effect on precipitation δ18O will be counterbalanced at least partly by opposing effects
during calcification. We can’t rule out the influence of monsoon precipitation on the millennial
variations we observe, but we favor the winter amount (storm track) explanation. Background
climate conditions likely favored a weak monsoon at this time13, and studies that argue for a
glacial monsoon14 still maintain that it did not exceed the strength of today’s monsoon (which
exerts minimal influence on cave dripwaters). Unlike the century-millenium scale variations, the
low-frequency behavior of the speleothem δ18O record may in fact reflect orbitally forced
monsoon changes 8. Finally, vapor source and trajectory can also influence these records;
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supplementary information
significant variation among storms with different trajectories has been noted in the White
Mountains (CA), although the relationship is complex15. The significant correlation between
winter precipitation amount and δ18O today (Supplementary Figure 1) suggests that even if this
factor is important, it does not overwhelm the inverse relationship we observe between amount
and δ18O of precipitation. In fact, large-scale stadial-interstadial changes across the Pacific could
result in trajectory shifts that reinforce precipitation amount changes in our isotopic record, if for
example stadial conditions included a shift to more distant moisture sources and a longer path for
Rayleigh distillation, concurrent with a southward-displaced storm track that delivers more
moisture.
Supplementary References Cited:
1
2
3
4
5
6
7
8
9
10
11
Buecher, B. Microclimate study of Kartchner Caverns. Arizona. Journal of Cave and
Karst Studies 61, 108-120 (1999).
Cheng, H. et al. The half-lives of uranium-234 and thorium-230. Chemical Geology 169,
17-33 (2000).
Placzek, C., Patchett, P. J., Quade, J. & Wagner, J. D. M. Strategies for successful U-Th
dating of paleolake carbonates: An example from the Bolivian Altiplano. Geochemistry
Geophysics Geosystems 7 (2006).
Robinson, L. F., Henderson, G. M. & Slowey, N. C. U-Th dating of marine isotope stage
7 in Bahamas slope sediments. Earth And Planetary Science Letters 196, 175-187 (2002).
Lea, D. W., Martin, P. A., Pak, D. K. & Spero, H. J. Reconstructing a 350 ky history of
sea level using planktonic Mg/Ca and oxygen isotope records from a Cocos Ridge core.
Quaternary Science Reviews 21, 283-293 (2002).
Hendy, C. The isotopic geochemistry of speleothems - I: The calculation of the effects of
different modes of formation on the isotopic composition of speleothems and their
applicability to paleoclimatic reconstruction. Geochimica Cosmoshimica Acta 35, 801824 (1971).
Mickler, P. J., Stern, L. A. & Banner, J. L. Large kinetic isotope effects in modern
speleothems. Geological Society Of America Bulletin 118, 65-81 (2006).
Wagner, J. D. M. Speleothem Record of Southern Arizona Paleoclimate, 3.5-54 KA,
University of Arizona, (2006).
Long, A. & Eastoe, C. Isotopic data from Tucson Arizona (University of Arizona, 2006).
Sheppard, P. R., Comrie, A. C., Packin, G. D., Angersbach, K. & Hughes, M. K. The
climate of the US Southwest. Clim. Res. 21, 219-238 (2002).
Brito-Castillo, L., Douglas, A. V., Leyva-Contreras, A. & Lluch-Belda, D. The effect of
large-scale circulation on precipitation and streamflow in the Gulf of California
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supplementary information
12
13
14
15
doi: 10.1038/ngeo707
continental watershed. International Journal of Climatology 23, 751-768, doi:Doi
10.1002/Joc.913 (2003).
Cayan, D. R. & Peterson, D. H. in Aspects of Climate Variability in the Pacific and the
Western Americas Geophysical Monograph (ed D.H. Peterson) 375-397 (American
Geophysical Union, 1989).
Anderson, R. S., Betancourt, J. L., Mead, J. I., Hevly, R. H. & Adam, D. P. Middle- and
late-Wisconsin paleobotanic and paleoclimatic records from the southern Colorado
Plateau, USA. Paleogeogr. Paleoclimatol. Paleoecol. 155, 31-57 (2000).
Holmgren, C. A., Norris, J. & Betancourt, J. L. Inferences about winter temperatures and
summer rains from the late Quaternary record of C-4 perennial grasses and C-3 desert
shrubs in the northern Chihuahuan Desert. Journal Of Quaternary Science 22, 141-161
(2007).
Friedman, I., Harris, J. M., Smith, G. I. & Johnson, C. A. Stable isotope composition of
waters in the Great Basin, United States - 1. Air-mass trajectories. J. Geophys. Res.Atmos. 107, doi:4400.10.1029/2001jd000565 (2002).
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supplementary information
doi: 10.1038/ngeo707
Supplementary Table 1. Uranium-thorium measurements on Cave of the Bells speleothem
COB-01-02. Ages were calculated using decay constants from Cheng et al. (2000) and corrected
for initial Th assuming an estimated value for 230Th/232Th activity of 0.8 ± 50%; such age
corrections were on the order of decades. Hiatuses at 3.5 and 27 mm are indicated by the H at
right.
#
$
$
$
&
#
$
&
&
#
&
*
*
$
$
#
$
$
$
#
$
$
#
*
*
*
*
*
*
#
#
$
*
*
*
*
*
Depth
Range
Center
Depth
mm
mm
Agea
yr before
1950
1-6
1-6R
3-5
5-7
7-10
7-12
7-12R
10-11.5
12.5-14
12.5-16.5
14-15.5
16-19
19-21.5
19.75-21.75
21.75-23.25
21-25
23.25-25
25-26.75
26.75-28.5
30-34
33-34.5
36-37.25
35-39
40.5-43
47.5-49.5
49.5-51.5
51.5-53.5
53.5-55.5
55.5-57.5
55-60
55-60R a
55-60R b
60-62
62-64
64-65.5
65.5-67
67-68.75
3.5
3.5
4
6
8.5
9.5
9.5
10.75
13.25
14.5
14.75
17.5
20.25
20.75
22.5
23
24.125
25.875
27.625
32
33.75
36.625
37
41.75
48.5
50.5
52.5
54.5
56.5
57.5
57.5
57.5
61
63
64.75
66.25
67.875
9487
10266
11009
11784
12469
12013
12211
13456
12997
12696
13137
14641
16746
16406
19781
18255
20868
23149
30441
31934
33809
34663
34566
36883
38607
38422
39776
40382
40424
39509
39974
40159
41025
40691
41491
41510
41260
Errorb
2σ
138
128
56
48
207
94
135
232
218
113
218
105
120
81
136
123
76
109
101
239
105
109
224
295
173
166
184
165
239
343
190
499
172
177
167
170
215
230
Th/238U
measured
0.20526
0.22216
0.23712
0.25696
0.27294
0.26213
0.26730
0.29358
0.28360
0.27814
0.28585
0.32176
0.37209
0.36518
0.43519
0.40303
0.45925
0.50565
0.60944
0.63977
0.67389
0.69262
0.68410
0.73118
0.77468
0.77813
0.79912
0.80541
0.80756
0.79094
0.79678
0.80201
0.82267
0.81926
0.82660
0.82687
0.82097
230
Th/238U
230
Th/232Th
corrected
0.20520
0.22198
0.23643
0.25666
0.27248
0.26208
0.26729
0.29351
0.28345
0.27799
0.28575
0.32047
0.37007
0.36400
0.43221
0.40198
0.45888
0.50421
0.60919
0.63974
0.67386
0.69259
0.68407
0.73111
0.77462
0.77761
0.79837
0.80530
0.80748
0.79089
0.79658
0.80184
0.82261
0.81920
0.82654
0.82675
0.82090
238
U
(234U/238U)int
ppm
2280
862
248
635
424
4011
17384
3032
1270
1371
1978
174
126
213
97
260
830
226
1491
11565
14191
13336
12067
5678
7543
847
586
3920
5538
8312
2235
2600
8012
7428
7043
3992
6371
0.160
0.158
0.153
0.191
0.187
0.188
0.183
0.168
0.218
0.200
0.206
0.247
0.234
0.226
0.227
0.225
0.245
0.217
0.197
0.186
0.183
0.208
0.188
0.188
0.206
0.213
0.205
0.188
0.187
0.188
0.188
0.187
0.208
0.232
0.205
0.198
0.200
2.47
2.48
2.48
2.52
2.54
2.53
2.54
2.55
2.54
2.55
2.54
2.58
2.63
2.64
2.65
2.65
2.68
2.69
2.57
2.59
2.61
2.62
2.60
2.63
2.69
2.71
2.71
2.70
2.71
2.70
2.69
2.70
2.73
2.73
2.71
2.71
2.71
H
H
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supplementary information
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* 68.75-71
69.875
42069
160
0.83658
0.83647
4331 0.228
2.72
* 73-75
74
43777
174
0.86890
0.86846
1054 0.236
2.74
* 75-76.5
75.75
44769
250
0.88994
0.88933
784 0.238
2.76
* 76.5-78.5
77.5
44494
207
0.89137
0.89118
2428 0.234
2.77
* 80.5-82
81.25
45465
253
0.90318
0.90313
9919 0.219
2.77
* 82-84
83
45627
254
0.90840
0.90831
5050 0.242
2.77
* 86-88
87
46244
170
0.90676
0.90667
5599 0.243
2.74
* 88-90
89
46194
207
0.90053
0.90046
6768 0.209
2.72
* 90-92
91
46638
193
0.90821
0.90813
5778 0.212
2.73
* 92-94.5
93.25
46654
242
0.90584
0.90576
6183 0.186
2.72
* 94.5-96.5
95.5
46770
170
0.90434
0.90427
6306 0.217
2.71
* 96.5-98.5
97.5
47767
233
0.92366
0.92356
4654 0.132
2.72
* 98.5-100
99.25
47034
211
0.90021
0.90012
5149 0.154
2.68
* 100-102
101
47512
226
0.90630
0.90622
5786 0.162
2.68
* 102-104.5
103.25
47585
220
0.89960
0.89952
5904 0.200
2.66
* 104.5-106
105.25
48202
285
0.90607
0.90598
5044 0.191
2.65
* 106-108
107
50075
343
0.94105
0.93655
106 0.195
2.67
* 108-109.5
108.75
50425
379
0.95594
0.95183
117 0.199
2.70
* 109.5-111
110.25
50256
308
0.96089
0.95966
392 0.181
2.73
# 110-114R
112
50657
734
0.96309
0.96047
185 0.176
2.71
* 114.5-115.5
115
52271
249
1.00886
1.00868
2834 0.157
2.78
# 115-121
118
50764
712
0.98177
0.98161
3112 0.156
2.77
$ 115-121R
118
51718
650
0.99514
0.99483
1582 0.152
2.77
# 121-126
123.5
52660
368
1.02352
1.02298
931 0.155
2.81
# 121-126R
123.5
52735
351
1.02130
1.02122
6803 0.166
2.80
a
Ages corrected assuming initial Th has a value similar to bulk upper continental crust, 230Th/232Th = 0.8
b
Error for all samples includes measurement error, decay constant uncertainty, and initial Th assuming an estimated
value for 230Th/232Th activity of 0.8 ± 50%
* UA-U on TIMS, Oxford-Th on MC-ICP-MS
# UA-U and Th on TIMS
$ UA- U and Th on MC-ICP-MS
& UA- U on MC-ICP-MS, Oxford- Th on MC-ICP-MS
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doi: 10.1038/ngeo707
7.40
7.50
7.60
7.70
7.80
7.90
8.00
8.10
8.20
8.30
8.40
8.50
8.60
8.70
8.80
8.90
9.00
9.10
9.20
9.30
9.40
9.50
9.60
9.70
9.80
9.90
10.00
10.10
10.20
10.30
10.40
10.50
10.60
10.70
11.00
11.10
11.20
11.30
11.40
11.50
11.60
11.70
11.80
11.90
12.00
12.10
12.20
12.30
Supplementary Table 2
Oxygen isotopic data, COB-01-02.
Depth
(mm)
3.50
3.60
3.70
3.80
3.90
4.00
4.10
4.20
4.30
4.40
4.50
4.60
4.70
4.80
4.90
5.00
5.10
5.20
5.30
5.40
5.50
5.60
5.70
5.80
5.90
6.00
6.10
6.20
6.30
6.40
6.50
6.60
6.70
6.80
6.90
7.00
7.10
7.20
7.30
Age
(years
before
1950)
11484
11507
11529
11552
11573
11594
11615
11636
11655
11675
11694
11713
11731
11749
11767
11784
11801
11817
11833
11849
11865
11880
11895
11910
11924
11938
11952
11966
11980
11993
12006
12019
12032
12044
12057
12069
12081
12093
12105
Measured
δ18O
(‰)
-8.510
-9.302
-9.406
-9.434
-9.517
-9.569
-9.514
-9.474
-9.349
-9.366
-9.531
-9.619
-9.491
-9.589
-9.553
-9.654
-9.808
-9.784
-9.836
-9.738
-9.455
-9.504
-9.778
-9.776
-9.802
-9.939
-9.872
-9.775
-9.790
-9.518
-9.663
-9.595
-9.298
-9.573
-9.603
-9.406
-9.448
-9.620
-9.787
Ice vol.
corrected
δ18O
(‰)
-8.852
-9.644
-9.748
-9.777
-9.861
-9.913
-9.858
-9.819
-9.695
-9.711
-9.877
-9.966
-9.837
-9.936
-9.901
-10.002
-10.156
-10.133
-10.184
-10.087
-9.804
-9.853
-10.127
-10.128
-10.154
-10.292
-10.226
-10.131
-10.147
-9.876
-10.022
-9.955
-9.660
-9.936
-9.967
-9.771
-9.815
-9.987
-10.155
12117
12128
12140
12151
12163
12174
12185
12196
12208
12219
12230
12241
12252
12264
12275
12286
12298
12309
12321
12332
12344
12356
12367
12379
12392
12404
12416
12429
12442
12455
12468
12481
12495
12509
12552
12567
12582
12597
12613
12629
12645
12662
12679
12696
12714
12732
12750
12769
-10.088
-10.145
-10.223
-10.063
-9.927
-9.673
-9.615
-9.470
-9.163
-9.049
-9.080
-9.035
-9.460
-9.698
-9.772
-9.833
-9.583
-9.587
-9.341
-9.056
-9.179
-9.085
-8.966
-9.277
-9.095
-9.321
-9.408
-9.331
-9.658
-9.648
-9.566
-9.561
-9.733
-9.812
-9.710
-9.124
-9.229
-9.271
-9.399
-9.217
-9.221
-9.423
-9.587
-9.621
-9.739
-9.755
-9.821
-9.837
-10.458
-10.516
-10.595
-10.436
-10.301
-10.048
-9.991
-9.848
-9.541
-9.428
-9.461
-9.416
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nature geoscience | www.nature.com/naturegeoscience
supplementary information
doi: 10.1038/ngeo707
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nature geoscience | www.nature.com/naturegeoscience
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supplementary information
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nature geoscience | www.nature.com/naturegeoscience
supplementary information
doi: 10.1038/ngeo707
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supplementary information
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supplementary information
doi: 10.1038/ngeo707
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nature geoscience | www.nature.com/naturegeoscience
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supplementary information
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doi: 10.1038/ngeo707
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supplementary information
doi: 10.1038/ngeo707
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nature geoscience | www.nature.com/naturegeoscience
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nature geoscience | www.nature.com/naturegeoscience
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doi: 10.1038/ngeo707
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doi: 10.1038/ngeo707
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nature geoscience | www.nature.com/naturegeoscience
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supplementary information
doi: 10.1038/ngeo707
Supplementary figure captions:
Supplementary figure 1. Climate-isotope relationships for Tucson precipitation, stratified
by half-season. Winter (October-March) data are shown in blue, and summer monsoon (JulySept.) data are shown in red. We selected these seasons to isolate particular climate dynamics
regimes (winter westerlies and summer monsoon, respectively); the remaining months contribute
less than 10% to the region’s precipitation. All isotope data are amount-weighted means for
seasons between 1984-2004. We omitted 1989 from this analysis because data are scarce and
noisy 8. A. Temperature-isotope correlations are weak, even inverse, in this region. B.
Correlations between precipitation amount and δ18O are significant at >98% (winter) and
>99.9% (summer). If the April-September half-year is substituted for the monsoon season (to
include the full annual cycle), the relationships do not change in sign, but the amount effect on
precipitation is weakened (r2 = 0.25) and the temperature effect slightly strengthened (r2 = 0.07).
Supplementary figure 2. Modern isotope and climate data from the Cave of the Bells
region. A. Average monthly rainfall δ18O (red, with standard deviation indicated by vertical
bars) from a 20-year dataset of episode-based rainfall isotope data 8,9. Average monthly rainfall
amount (blue) and monthly air temperature (yellow) are also shown. Grey shading indicates the
winter precipitation season; the monsoon season runs from late June-early September. Black
horizontal line indicates average dripwater δ18O from Cave of the Bells, which matches winter
precipitation. B. Oxygen isotopic data from the cave site; δ18O of rainwater from a gauge
established above the cave (green line) and of drip waters from three sites within the cave (red,
orange, and blue lines). The offset among the sites spans 0.35‰ and the standard deviation of
precipitation within each site is 0.12-0.26‰. In summer 2006 (arrow) and afterwards, following
an especially strong monsoon season, higher dripwater δ18O values are seen at two sites (red and
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supplementary information
orange lines), and one of these (red line) shows an immediate pulse of isotopically heavier water.
Winter months (Oct.-March) are shaded grey. The dripwater values generally match the average
winter-season (grey shaded) precipitation, although our precipitation dataset is noisy.
Supplementary figure 3. Photo of COB slab used for isotopic analysis and U/Th dating.
Thin red arrows (at sides) point to trench used for isotopic sampling. Thick black arrows indicate
the presence of faint growth bands that were used to determine the sampling transect. This core
displayed very faint growth features not obvious on this image that are consistent in orientation
down the 140-mm length of the sample. The core appears homogeneous and translucent.
Supplementary figure 4. Plot of U/Th date (age before 1950) versus depth for sample COB01-02. Colors indicate whether samples were run at the University of Arizona (UA) or Oxford,
and the method used, either muticollector inductively coupled mass spectrometer (MC-ICP-MS)
or thermal ionization mass spectrometry (TIMS). Red: UA TIMS; blue: UA MC-ICP-MS; green:
U on UA MC-ICP-MS and Th on Oxford MC-ICP-MS; black: U on UA TIMS and Th on
Oxford MC-ICP-MS. Thin lines indicate the models used to assign ages to oxygen isotopic
samples. Error bars represent 2σ analytical uncertainty (vertical) and depth range of sample
(horizontal).
Supplementary figure 5. Correlation plot between δ18O and δ13C, for all data (black points and
black linear fit) and for specific time intervals (MIS3 in pink with red linear fit; deglacial in light
blue with blue linear fit). Note that the colored points overlie most of the black dots. If isotopic
disequilibrium were significant in this sample, we would observe a strong correlation between
oxygen and carbon isotope values7, but this plot demonstrates that the correlation is weak and
thus that disequilibrium effects do not influence our record, according to published criteria7.
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Supplementary figure 1
Wagner et al.
a.
0
y = -0.0129x - 8.7252
R2= 0.0002
Precipitation δ18O (‰)
-2
-4
-6
-8
y = 0.3405x - 14.539
R2= 0.1116
-10
Winter (Oct-Mar)
Monsoon (July-Sept)
-12
-14
8
13
18
23
Mean Temperature
b.
0
30
Winter (Oct-Mar)
Monsoon (July-Sept)
-2
Precipitation δ18O (‰)
28
y = -0.0138x - 2.824
R 2 = 0.5039
-4
-6
-8
-10
y = -0.0083x - 7.5677
R2= 0.2712
-12
-14
0
100
200
300
Seasonal precipitation total (mm)
400
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doi: 10.1038/ngeo707
Supplementary figure 2
Wagner et al.
2
A.
0
δ18O (‰)
-2
-4
-6
-10
Rainfall (mm/month)
60
-8
40
-12
Temperature (°C)
20
0
30
20
10
Jan
B.
Mar
May
Jul
Sep
Nov
Month
0
Precipitation δ18O (‰)
-2
Local rainfall δ18O
-4
-6
-8
-10
Cave drip water δ18O
-12
-14
-16
Jan July Jan July Jan July Jan July Jan July
2003 2003 2004 2004 2005 2005 2006 2006 2007 2007
Month and year
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Supplementary figure 3
Wagner et al.
Top
Bottom
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Supplementary figure 4
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Supplementary figure 5
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