Confidential manuscript submitted to Paleoceanography
Supporting Information for “The climatic significance of Late Ordovician-early Silurian black shales” A. Pohl1 , Y. Donnadieu1,2 , G. Le Hir3 , and D. Ferreira4
1 Laboratoire
des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France 2 Aix
3 IPGP
Marseille Univ, CNRS, IRD, Coll France, CEREGE, Aix-en-Provence, France
– Institut de Physique du Globe de Paris, Université Paris7-Denis Diderot, 1 rue Jussieu, 75005 Paris, France 4 Department
of Meteorology, University of Reading, Reading, United Kingdom
Contents 1. Figures S1 to S10
Corresponding author: A. Pohl,
[email protected]
–1–
Confidential manuscript submitted to Paleoceanography
[O2] (μmol.L-1)
300
200
100
0 450
Z= 5 m Z= 45 m Z= 82 m Z= 185 m Z= 595 m
460
470
480
Z= 1156 m Z= 1579 m Z= 2186 m Z= 3138 m Z= 3752 m
490
500
Model year
Figure S1.
Evolution of the mean annual, globally-averaged ocean oxygen concentration during the last 50
years of the simulation run at 350 W.m−2 with present-day atmospheric pO2 , shown at various water depths from the ocean surface to the sea floor. The climatology file was built by restarting the model from year 500 for 50 additional years, and subsequently averaging monthly climatic fields over these last 50 years.
90°
x 10-4 9.0
30°
8.0 7.0
0°
6.0 5.0
30°
4.0 3.0
60° 90°
Figure S2.
Marine primary productivity simulated using the 440 Ma land-sea mask and a solar forcing
level of 350 W.m−2 . Numbered Katian data points are from the compilation of Melchin et al. [2013].
–2–
Primary productivity (mol.m-3.yr-1)
60°
Confidential manuscript submitted to Paleoceanography
Topography - bathymetry (km)
0°
A
3 2
30°
1 0 -1
60°
-2 -3
B
90°
-4
0°
30
30°
20 15
60°
10 5
C
90°
0
0°
4.5
Runoff to the ocean (mm.day-1)
25
4 30°
3 2.5 2
60°
1.5 1 0.5
90°
Figure S3.
Runoff (mm.day-1)
3.5
0
Results of a simulation conducted by Pohl et al. [2016] using the FOAM model, the same (440
Ma) land-sea mask as used in our study, a solar forcing level of 330 W.m−2 and an atmospheric CO2 concentration of 4480 ppm. The FOAM model is a mixed-resolution ocean-atmosphere general circulation model widely used for paleoclimate studies (e.g., Donnadieu et al., 2016; see Pohl et al., 2016 for a description of the model and additional references). This model run is typified by a warm climate (mean annual, global surface air temperature: 24.3 ◦ C) that is highly comparable with the climate state simulated in the present study at 350 W.m−2 (mean SAT: 23.8 ◦ C). (A): Topography-bathymetry provided in input to the FOAM model. (B): Runoff to the ocean. (C): Near-surface winds (vectors) and continental runoff (shading).
–3–
Confidential manuscript submitted to Paleoceanography
A
90°
30° 0° 30° 60° 90° 90°
1000 900 800 700 600 500 400 300 200 100 0
60°
30° 0° 30° 60° 90°
Figure S4.
Convective adjustments
B
Mixed-layer depth (m)
200 180 160 140 120 100 80 60 40 20 0
60°
Comparison of the intensity of the ocean surface convection simulated at 350 W.m−2 with the
MITgcm and at 4480 ppm with the FOAM model, using the same 440 Ma continental configuration (see caption of Fig. S3). (A): MITgcm model run; mean annual mixed-layer depth. (B): FOAM experiment [Pohl et al., 2016]; the shading represents the number of times the surface ocean has undergone convective mixing summed over a year.
9.0
60°
8.0
30°
7.0 0°
6.0 5.0
30°
4.0
60°
3.0
90°
Figure S5.
Primary productivity (mol.m-3.yr-1)
x 10-4
90°
Mean annual surface primary productivity simulated using the present-day land-sea mask and
topography-bathymetry [ETOPO2v2, 2006], and otherwise Ordovician boundary conditions (see Sect. 2.2). The land surface is a rocky desert. The solar forcing value is set to 350 W.m−2 .
–4–
Confidential manuscript submitted to Paleoceanography
0
Depth (km)
0.5
pO2 = 1.0 pO2 = 0.8 pO2 = 0.6 pO2 = 0.4 pO2 = 0.2
1 1.5 2 2.5 3 3.5 40
50
100
150
200
[O2] (μmol.L-1)
Figure S6.
Mean annual, globally-averaged oxygen concentration simulated throughout the water column
using the 440 Ma land-sea mask, a solar forcing level of 350 W.m−2 and various atmospheric O2 concentrations between 1.0 and 0.2 times the present-day value. The insert in the bottom-right corner displays the area over which simulated oxygen water content is averaged (global domain).
A
90°
250
60°
150
0°
100 30°
[O2] (μmol.L-1)
200
30°
50 60°
B
0
90° 90°
250
60°
150
0°
100
30°
[O2] (μmol.L-1)
200
30°
50 60° 90°
Figure S7.
Dissolved oxygen concentration simulated at the ocean bottom, using the 440 Ma land-sea
mask, a pO2 set to 0.4 times the present-day value and solar forcing levels of 350 W.m−2 (A) and 345 W.m−2 (B).
–5–
Over. stream. maximum (Sv)
Confidential manuscript submitted to Paleoceanography
Figure S8.
30 25 20 15 10 5 0
0
100
200
300
400
500
600
Model years
700
800
900
1000
Results of the freshwater hosing experiments conducted at 350 W.m−2 . Evolution of the in-
tensity of the meridional overturning streamfunction as a function of model integration time for 3 values of imposed freshwater flux: 0.1 Sv (light grey line), 0.5 Sv (dark grey line) and 1 Sv (black line). The intensity of the streamfunction is computed, for each model year, as the maximum of the absolute value of the mean
Over. stream. maximum (Sv)
annual meridional streamfunction between 500 m depth and the ocean bottom, and between 90 ◦ S and 30 ◦ S.
Figure S9.
25 20 15 10 5 0
0
100
200
300
400
500
600
Model years
700
800
900
1000
Results of the freshwater hosing experiment conducted under a warming climate. The sim-
ulation is restarted from the climatic steady-state simulated at 345 W.m−2 , and a solar forcing level of 350 W.m−2 is imposed during the model run. The black curve represents the evolution of the intensity of the meridional overturning streamfunction as a function of model integration time with a freshwater flux of 1 Sv. The intensity of the streamfunction is computed as the maximum of the absolute value of the mean annual meridional streamfunction between 500 m depth and the ocean bottom, and between 90 ◦ S and 30 ◦ S.
–6–
Confidential manuscript submitted to Paleoceanography
Annual wind stress (N m-2)
0.15 0.1 0.05 0 -0.05 -0.1
-80
-60
-40
-20
0
20
40
60
80
Latitude
Figure S10.
Mean annual zonal wind stress (expressed in N.m−2 ) simulated at 350 W.m−2 with the MIT-
gcm (blue line) and at 4480 ppm with the FOAM model (red line), using the same 440 Ma continental configuration (Pohl et al., 2016a, see caption of Fig. S3).
–7–
Confidential manuscript submitted to Paleoceanography
References Donnadieu, Y., E. Pucéat, M. Moiroud, F. Guillocheau, and J.-F. Deconinck (2016), A betterventilated ocean triggered by Late Cretaceous changes in continental configuration., Nature communications, 7, 10,316. ETOPO2v2 (2006), 2-minute gridded global relief data (ETOPO2v2), U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center. Melchin, M. J., C. E. Mitchell, C. Holmden, and P. Štorch (2013), Environmental changes in the Late Ordovician-early Silurian: Review and new insights from black shales and nitrogen isotopes, Geological Society of America Bulletin, 125(11-12), 1635–1670. Pohl, A., E. Nardin, T. Vandenbroucke, and Y. Donnadieu (2016), High dependence of Ordovician ocean surface circulation on atmospheric CO2 levels, Palaeogeography, palaeoclimatology, palaeoecology, 458, 39–51.
–8–
