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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2025-5840</article-id>
<title-group>
<article-title>The Marine Isotopic Stage 7: a relic of the &quot;41-ka world&quot;? Perspectives from a global-scale sea-surface temperature synthesis</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Legrain</surname>
<given-names>Etienne</given-names>
<ext-link>https://orcid.org/0000-0002-7446-0718</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Stevenard</surname>
<given-names>Nathan</given-names>
<ext-link>https://orcid.org/0000-0002-1838-9291</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Capron</surname>
<given-names>Emilie</given-names>
<ext-link>https://orcid.org/0000-0003-0784-1884</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Parrenin</surname>
<given-names>Frédéric</given-names>
<ext-link>https://orcid.org/0000-0002-9489-3991</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Vazquez Riveiros</surname>
<given-names>Natalia</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Université Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, Grenoble, France</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Water and Climate, Vrije Universiteit Brussel, Brussels, Belgium</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Laboratoire de Glaciologie, Université libre de Bruxelles, Brussels, Belgium</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Geo-Ocean, UMR 6538, CNRS/Université de Bretagne Occidentale/Ifremer, Plouzané, France</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>These two authors contributed equally to this work.</addr-line>
</aff>
<pub-date pub-type="epub">
<day>28</day>
<month>11</month>
<year>2025</year>
</pub-date>
<volume>2025</volume>
<fpage>1</fpage>
<lpage>29</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2025 Etienne Legrain et al.</copyright-statement>
<copyright-year>2025</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5840/">This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5840/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5840/egusphere-2025-5840.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5840/egusphere-2025-5840.pdf</self-uri>
<abstract>
<p>The Marine Isotope Stage 7 (MIS 7, ~ 245&amp;ndash;190 ka) displays an unusual morphology compared to the other interglacials of the late Pleistocene. It comprises two major warm periods (MIS 7e and MIS 7c) each preceded by multi-millennial-scale warming intervals (Termination III (TIII) and TIIIa, respectively) and separated by a brief return to glacial conditions (MIS 7d). When considered as two distinct warm phases, MIS 7 has been compared to the 41-ka obliquity-driven climate cycles of the pre-mid-Pleistocene transition (MPT) world. However, a coherent spatio-temporal picture of MIS 7 surface temperature remains lacking to enable a comprehensive comparison with other interglacials. Here we compiled 132 high-resolution (better than 4 ka) sea surface temperature (SST) records derived from 85 marine sites over the time interval 260&amp;ndash;190 ka. In order to provide a spatio-temporal comparison of these records, we (i) align them on a common temporal framework relying on the AICC2023 reference ice core chronology and (ii) recompute SSTs using a homogenized proxy-calibration, both steps applying Bayesian and Monte Carlo approaches to quantify the attached uncertainty. Finally, we produce global and regional stacks of SST anomalies relative to the pre-industrial covering TIII and the following MIS 7.&lt;/p&gt;
&lt;p&gt;Our results evidence that global mean surface temperature remains below pre-industrial (PI) values over both MIS 7e (-1.4 &amp;plusmn; 0.3 &amp;deg;C) and MIS 7c (-1.0 &amp;plusmn; 0.3 &amp;deg;C) periods. The warmest phase across MIS 7 occurs during the MIS 7c substage, a period when atmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentrations are 30 ppm lower than during MIS 7e, highlighting a decoupling between radiative forcing and the global surface temperature response. In addition, TIII exhibits a greater warming amplitude than TIIIa, both globally and regionally. The spatial and temporal dynamics of the two terminations differ markedly. TIII follows a &quot;classic&quot; sequential deglaciation pattern, with an early warming initiated in the Southern Hemisphere, which then gradually propagates toward the Northern Hemisphere. In contrast, TIIIa displays near-synchronous warming across all latitudes, lacking the interhemispheric pattern typical of classical terminations. This suggests that TIIIa is not a standard glacial termination, but rather a distinct climatic transition. Supporting this, correlation analyses between orbital parameters and regional SST stacks evidence the role of obliquity in shaping MIS 7 temperature records, likely due to the most extreme obliquity values of the Pleistocene occurring over this period. We therefore propose that TIIIa is the result of a self-sustained climatic oscillation that temporarily re-synchronised to the 41-ka cycles because of an exceptional orbital context. As a result, MIS 7 represents a hybrid interglacial, embedded within the post-MPT 100-ka framework, yet shaped by obliquity-driven forcing such as during the early Pleistocene.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>Agence Nationale de la Recherche</funding-source>
<award-id>ANR-19-MPGA-0001</award-id>
</award-group>
<award-group id="gs2">
<funding-source>Belgian Federal Science Policy Office</funding-source>
<award-id>FROID</award-id>
</award-group>
<award-group id="gs3">
<funding-source>Fonds Wetenschappelijk Onderzoek</funding-source>
<award-id>CAPSULE</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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