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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>
<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-2026-6172</article-id>
<title-group>
<article-title>Subtropical gyres dominate global calcium carbonate production by coccolithophores</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wiseman</surname>
<given-names>Nicola A.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>de Vries</surname>
<given-names>Joost</given-names>
<ext-link>https://orcid.org/0000-0003-3427-6921</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Poulton</surname>
<given-names>Alex J.</given-names>
<ext-link>https://orcid.org/0000-0002-5149-6961</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Marsh</surname>
<given-names>Nichole J.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wolf</surname>
<given-names>Levi J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Monteiro</surname>
<given-names>Fanny M.</given-names>
<ext-link>https://orcid.org/0000-0002-8790-0188</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Earth, Ocean, and Ecological Sciences, University of Liverpool, Liverpool L69 3GP, UK</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>The Lyell Centre for Earth and Marine Science, Heriot-Watt University, Edinburgh EH14 4AS, UK</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Centre for ice, Cryosphere, Carbon and Climate (iC3), Department of Geosciences, UiT The Arctic University of Norway, 9019, Tromsø, Norway</addr-line>
</aff>
<pub-date pub-type="epub">
<day>12</day>
<month>10</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>22</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Nicola A. Wiseman et al.</copyright-statement>
<copyright-year>2026</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/2026/egusphere-2026-6172/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6172/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6172/egusphere-2026-6172.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6172/egusphere-2026-6172.pdf</self-uri>
<abstract>
<p>Marine calcifying phytoplankton known as coccolithophores are a key part of the ocean carbon cycling, contributing to both the export of organic matter via the biological pump and the establishment of the vertical seawater alkalinity gradient known as a the carbonate counter pump. As dominate producers of calcium carbonate production, the rate at which coccolithophores produce calcium carbonate, determines the magnitude of the carbonate counter pump, and is sensitive to future changes in temperature, pH, and nutrient and light availability. Our understanding of spatiotemporal distributions of calcium carbonate production is limited, as measuring calcium carbonate production at sea is labour-intensive, and currently biased both seasonally and spatially. Here we leverage novel machine learning techniques to predict calcium carbonate production on a global scale to a depth of 200m, providing resolution with depth that has not been possible for previous remote sensing based approaches. We find a global integrated annual production of 1.23 PgC/yr [0.78&amp;ndash;1.71], with the majority (59%) occurring in the subtropical gyres, challenging the dominance of more-often studied high latitude bloom regions. Our model also shows 18% of global annual CP occurring below the euphotic zone. Our results highlight the need for additional sampling and process studies in the subtropical gyres and at low lights levels/deep in the water column in particular to further constrain our understanding of the ocean carbonate cycle.</p>
</abstract>
<counts><page-count count="22"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Natural Environment Research Council</funding-source>
<award-id>NE/X001261/1</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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