Supplemental Material
Journal of Climate
Future Changes in the Intensity and Duration of Marine Heat and Cold Waves: Insights from
Coupled Model Initial-Condition Large Ensembles
https://doi.org/10.1175/JCLI-D-23-0278.1© Copyright 2024 American Meteorological Society (AMS)
For permission to reuse any portion of this work, please contact
permissions@ametsoc.org. Any use of material in this work that is determined to be “fairuse” under Section 107 of the U.S. Copyright Act (17 USC §107) or that satisfies theconditions specified in Section 108 of the U.S. Copyright Act (17 USC §108) does not
require AMS’s permission. Republication, systematic reproduction, posting in electronicform, such as on a website or in a searchable database, or other uses of this material,
except as exempted by the above statement, requires written permission or a licensefrom AMS. All AMS journals and monograph publications are registered with the
Copyright Clearance Center (https://www.copyright.com). Additional details are provided
in the AMS Copyright Policy statement, available on the AMS website(https://www.ametsoc.org/PUBSCopyrightPolicy).

12

Supplemental Materials

34“Future changes in the Intensity and Duration of Marine Heat and Cold Waves:

5Insights from Coupled Model Initial-Condition Large Ensembles”

67Clara Deser1,*, Adam S. Phillips1, Michael. A. Alexander2, Dillon J. Amaya2, Antonietta

8Capotondi2,3, Michael G. Jacox2,4,5 and James D. Scott2,3

9
10

1 National Center for Atmospheric Research, Boulder CO

112 NOAA Physical Sciences Laboratory, Boulder CO

123 CIRES, University of Colorado, Boulder, CO

134 NOAA Southwest Fisheries Science Center, Monterey, CA

145 University of California Santa Cruz, Santa Cruz, CA

1516

Submitted to Journal of Climate17May 9, 2023

18

Revised October 8, 2023

1920212223

Contents: 43 Supplemental Figures (Figs. S1-43).

2425262728
2930

Figure S1. Number of discrete MHW and MCW events per 31 years (average of 1970-2000,2020-2050 and 2070-2100). (a,g) CESM2; (b,h) CanESM5; (c,i) GFDL-SPEAR; (d,j) MIROC6;(e,k) CESM1; (f,l) CanESM2; (g,o) MPI-ESM-LR. The number in the upper right of each panel
denotes the average value over the global ocean.

3132
33
34

Figure S2. As in Fig. S1 but for ENSO-neutral events.

3536373839404142

Figure S3. Composite MHW and MCW intensity (ºC) during 1950-2020 from the 50-member
CanESM5 Large Ensemble and Observations. (a,g) Ensemble average; (b,h) Observations; (c,i)
Ensemble average minus Observations; (d,j) Ensemble maximum; (e,k) Ensemble minimum; (f,l)
Ensemble maximum minus minimum. Gray shading in (c,i) indicates that observations lie within
the 5th-95th percentile range of the CanESM5 Large Ensemble.

43444546

Figure S4. As in Fig. S3 but for the 30-member GFDL-SPEAR Large Ensemble.

47
48
49
50

Figure S5. As in Fig. S3 but for the 50-member MIROC6 Large Ensemble.

51
52
53
54

Figure S6. As in Fig. S3 but for the 40-member CESM1 Large Ensemble.

55
56
57
58

Figure S7. As in Fig. S3 but for the 50-member CanESM2 Large Ensemble.

59
60
61
62

Figure S8. As in Fig. S3 but for the 100-member MPI-ESM-LR Large Ensemble.

63
64
65
66
67
68
69
70

Figure S9. Composite MHW and MCW duration (months) during 1950-2020 from the 50member CanESM5 Large Ensemble and Observations. (a,g) Ensemble average; (b,h)
Observations; (c,i) Ensemble average minus Observations; (d,j) Ensemble maximum; (e,k)
Ensemble minimum; (f,l) Ensemble maximum minus minimum. Gray shading in (c,i) indicatesthat observations lie within the 5th-95th percentile range of the CanESM5 Large Ensemble.

71
72
73
74

Figure S10. As in Fig. S9 but for the 30-member GFDL-SPEAR Large Ensemble.

75
76
7778

Figure S11. As in Fig. S9 but for the 50-member MIROC6 Large Ensemble.

79
80
81
82

Figure S12. As in Fig. S9 but for the 40-member CESM1 Large Ensemble.

83
84
85
86

Figure S13. As in Fig. S9 but for the 50-member CanESM2 Large Ensemble.

87
88
89
90

Figure S14. As in Fig. S9 but for the 100-member MPI-ESM-LR Large Ensemble.

91
92
93
94
95
96
97
98
99

Figure S15. Composite MHW and MCW intensity (ºC) from the 50-member CanESM5 Large
Ensemble during (a,f) 1970-2000, (b,g) 2020-2050, (c,h) 2070-2100, and differences (d,i) 20202050 minus 1970-2000, and (e,j) 2070-2100 minus 1970-2000. Note that the color bar range istwice as large in a-c, f-h compared to d-e, i-j. Gray shading in d-e, i-j indicates that the differences
are not statistically significant according to the False Discovery Rate applied to a 2-sided t-test at
the 95% confidence level.

100101102103

Figure S16. As in Fig. S15 but for the 30-member GFDL-SPEAR Large Ensemble.

104105
106
107

Figure S17. As in Fig. S15 but for the 50-member MIROC6 Large Ensemble.

108109110111

Figure S18. As in Fig. S15 but for the 40-member CESM1 Large Ensemble.

112
113
114
115

Figure S19. As in Fig. S15 but for the 50-member CanESM2 Large Ensemble.

116
117
118
119

Figure S20. As in Fig. S15 but for the 100-member MPI-ESM-LR Large Ensemble.

120
121
122
123
124
125
126
127
128

Figure S21. Composite MHW and MCW duration (months) from the 50-member CanESM5Large Ensemble during (a,f) 1970-2000, (b,g) 2020-2050, (c,h) 2070-2100, and differences (d,i)
2020-2050 minus 1970-2000, and (e,j) 2070-2100 minus 1970-2000. Note that the color bar range
is twice as large in a-c, f-h compared to d-e, i-j. Gray shading in d-e, i-j indicates that thedifferences are not statistically significant according to the False Discovery Rate applied to a 2sided t-test at the 95% confidence level.

129
130
131
132

Figure S22. As in Fig. S21 but for the 30-member GFDL-SPEAR Large Ensemble.

133
134
135
136

Figure S23. As in Fig. S21 but for the 50-member MIROC6 Large Ensemble.

137
138
139
140

Figure S24. As in Fig. S21 but for the 40-member CESM1 Large Ensemble.

141
142
143
144

Figure S25. As in Fig. S21 but for the 50-member CanESM2 Large Ensemble.

145
146
147
148

Figure S26. As in Fig. S21 but for the 100-member MPI-ESM-LR Large Ensemble.

149
150
151
152
153
154
155
156
157
158
159
160

Figure S27. Composite MHW and MCW intensity (ºC) differences between 2020-2050 and 19702000 for the ensemble-mean of each model Large Ensemble: (a,h) CESM2; (b,i) CanESM5; (c,j)
GFDL-SPEAR; (d,k) MIROC6; (e,l) CESM1; (f,m) CanESM2; (g,n) MPI-ESM-LR. Gray shadingindicates that the differences are not statistically significant according to the False Discovery Rateapplied to a 2-sided t-test at the 95% confidence level. The number in the upper right of each panel
denotes the fractional area (%) of significant differences (e.g., non-gray areas). Shading in panels(h,p) show locations where at least two-thirds of the models show statistically significant values(pink for positive and blue for negative); the number in the upper right denotes the fractional area(%) of the pink and blue shading.

161
162
163
164

Figure S28. As in Fig. S27 but for composite MHW and MCW duration (months).

165
166
167
168
169
170
171
172
173

Figure S29. Composite ENSO-neutral MHW and MCW intensity (ºC) from the 50-member
CanESM5 Large Ensemble during (a,f) 1970-2000, (b,g) 2020-2050, (c,h) 2070-2100, anddifferences (d,i) 2020-2050 minus 1970-2000, and (e,j) 2070-2100 minus 1970-2000. Note thatthe color bar range is twice as large in a-c, f-h compared to d-e, i-j. Gray shading in d-e, i-j indicatesthat the differences are not statistically significant according to the False Discovery Rate applied
to a 2-sided t-test at the 95% confidence level.

174
175
176
177

Figure S30. As in Fig. S29 but for the 30-member GFDL-SPEAR Large Ensemble.

178
179
180
181

Figure S31. As in Fig. S29 but for the 50-member MIROC6 Large Ensemble.

182
183
184
185

Figure S32. As in Fig. S29 but for the 40-member CESM1 Large Ensemble.

186
187
188
189

Figure S33. As in Fig. S29 but for the 50-member CanESM2 Large Ensemble.

190
191
192
193

Figure S34. As in Fig. S29 but for the 100-member MPI-ESM-LR Large Ensemble.

194
195
196197198
199200201
202

Figure S35. Composite ENSO-neutral MHW and MCW duration (months) from the 50-member
CanESM5 Large Ensemble during (a,f) 1970-2000, (b,g) 2020-2050, (c,h) 2070-2100, anddifferences (d,i) 2020-2050 minus 1970-2000, and (e,j) 2070-2100 minus 1970-2000. Note thatthe color bar range is twice as large in a-c, f-h compared to d-e, i-j. Gray shading in d-e, i-j indicatesthat the differences are not statistically significant according to the False Discovery Rate applied
to a 2-sided t-test at the 95% confidence level.

203
204
205
206

Figure S36. As in Fig. S35 but for the 30-member GFDL-SPEAR Large Ensemble.

207
208
209
210

Figure S37. As in Fig. S35 but for the 50-member MIROC6 Large Ensemble.

211
212
213
214

Figure S38. As in Fig. S35 but for the 40-member CESM1 Large Ensemble.

215
216
217
218

Figure S39. As in Fig. S35 but for the 50-member CanESM2 Large Ensemble.

219
220
221
222

Figure S40. As in Fig. S35 but for the 100-member MPI-ESM-LR Large Ensemble.

223
224225226227228229230231232233234

Figure S41. Composite ENSO-neutral MHW and MCW intensity (ºC) differences between
2020-2050 and 1970-2000 for the ensemble-mean of each model Large Ensemble: (a,h) CESM2;(b,i) CanESM5; (c,j) GFDL-SPEAR; (d,k) MIROC6; (e,l) CESM1; (f,m) CanESM2; (g,n) MPIESM-LR. Gray shading indicates that the differences are not statistically significant according to
the False Discovery Rate applied to a 2-sided t-test at the 95% confidence level. The number inthe upper right of each panel denotes the fractional area (%) of significant differences (e.g., nongray areas). Shading in panels (h,p) show locations where at least two-thirds of the models show
statistically significant values (pink for positive and blue for negative); the number in the upper
right denotes the fractional area (%) of the pink and blue shading.

235
236
237
238

Figure S42. As in Fig. S41 but for duration (months).

239
240
241
242
243
244
245
246
247

Figure S43. Ratio of mid-century changes (2020-2050 minus 1970-2000) in MHW and MCW
composite intensity due to changes in variability divided by that due to changes in variability-plusmean state for: (a,h) CESM2; (b,i) CanESM5; (c,j) GFDL-SPEAR; (d,k) MIROC6; (e,l) CESM1;(f,m) CanESM2; (g,n) MPI-ESM-LR. Panels h,p show the multi-model ensemble (MME) average.
The number in the upper right of each panel denotes the fractional area (%) of values within therange -0.1 to +0.1.