The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes
<p>The essential micronutrient iron (Fe) limits phytoplankton growth when dissolved Fe (dFe) concentrations are too low to meet biological demands. However, many of the processes that remove, supply, or transform Fe are poorly constrained, which limits our ability to predict how ocean producti...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-10-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/4197/2023/bg-20-4197-2023.pdf |
| _version_ | 1797661229058097152 |
|---|---|
| author | D. König D. König A. Tagliabue |
| author_facet | D. König D. König A. Tagliabue |
| author_sort | D. König |
| collection | DOAJ |
| description | <p>The essential micronutrient iron (Fe) limits
phytoplankton growth when dissolved Fe (dFe) concentrations are too low to
meet biological demands. However, many of the processes that remove, supply,
or transform Fe are poorly constrained, which limits our ability to predict
how ocean productivity responds to ongoing and future changes in climate. In
recent years, isotopic signatures (<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe) of Fe have increasingly been
used to gain insight into the ocean Fe cycle, as distinct <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe
endmembers of external Fe sources and <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe fractionation during
processes such as Fe uptake by phytoplankton can leave a characteristic
imprint on dFe signatures (<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span>). However, given the relative
novelty of these measurements, the temporal scale of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> observations is limited. Thus, it is unclear how the changes in ocean
physics and biogeochemistry associated with ongoing or future climate change
will affect <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> on interannual to decadal timescales. To
explore the response of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> to such climate variability,
we conducted a suite of experiments with a global ocean model with active
<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe cycling under two climate scenarios. The first scenario is based
on an atmospheric reanalysis and includes recent climate variability
(1958–2021), whereas the second comes from a historical and high-emissions
climate change simulation to 2100. We find that under recent climatic
conditions (1975–2021), interannual <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> variability is
highest in the tropical Pacific due to circulation and productivity changes
related to the El Niño–Southern Oscillation (ENSO), which alter both
endmember and uptake fractionation effects on <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> by
redistributing dFe from different external sources and shifting nutrient
limitation patterns. While the tropical Pacific will remain a hotspot of
<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> variability in the future, the most substantial end-of-century <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> changes will occur in the Southern Hemisphere at
middle to high latitudes. These arise from uptake fractionation effects due to
shifts in nutrient limitation. Based on these strong responses to climate
variability, ongoing measurements of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> may help diagnose
changes in external Fe supply and ocean nutrient limitation.</p> |
| first_indexed | 2024-03-11T18:42:21Z |
| format | Article |
| id | doaj.art-140ea594ca3b47da81c77255f0e54cf4 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-03-11T18:42:21Z |
| publishDate | 2023-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-140ea594ca3b47da81c77255f0e54cf42023-10-12T09:05:04ZengCopernicus PublicationsBiogeosciences1726-41701726-41892023-10-01204197421210.5194/bg-20-4197-2023The fingerprint of climate variability on the surface ocean cycling of iron and its isotopesD. König0D. König1A. Tagliabue2School of Environmental Sciences, University of Liverpool, Liverpool, L69 3GP, UKpresent address: Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai`i at Mānoa, Honolulu, HI, USASchool of Environmental Sciences, University of Liverpool, Liverpool, L69 3GP, UK<p>The essential micronutrient iron (Fe) limits phytoplankton growth when dissolved Fe (dFe) concentrations are too low to meet biological demands. However, many of the processes that remove, supply, or transform Fe are poorly constrained, which limits our ability to predict how ocean productivity responds to ongoing and future changes in climate. In recent years, isotopic signatures (<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe) of Fe have increasingly been used to gain insight into the ocean Fe cycle, as distinct <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe endmembers of external Fe sources and <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe fractionation during processes such as Fe uptake by phytoplankton can leave a characteristic imprint on dFe signatures (<span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span>). However, given the relative novelty of these measurements, the temporal scale of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> observations is limited. Thus, it is unclear how the changes in ocean physics and biogeochemistry associated with ongoing or future climate change will affect <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> on interannual to decadal timescales. To explore the response of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> to such climate variability, we conducted a suite of experiments with a global ocean model with active <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe cycling under two climate scenarios. The first scenario is based on an atmospheric reanalysis and includes recent climate variability (1958–2021), whereas the second comes from a historical and high-emissions climate change simulation to 2100. We find that under recent climatic conditions (1975–2021), interannual <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> variability is highest in the tropical Pacific due to circulation and productivity changes related to the El Niño–Southern Oscillation (ENSO), which alter both endmember and uptake fractionation effects on <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> by redistributing dFe from different external sources and shifting nutrient limitation patterns. While the tropical Pacific will remain a hotspot of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> variability in the future, the most substantial end-of-century <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> changes will occur in the Southern Hemisphere at middle to high latitudes. These arise from uptake fractionation effects due to shifts in nutrient limitation. Based on these strong responses to climate variability, ongoing measurements of <span class="inline-formula"><i>δ</i><sup>56</sup></span>Fe<span class="inline-formula"><sub>diss</sub></span> may help diagnose changes in external Fe supply and ocean nutrient limitation.</p>https://bg.copernicus.org/articles/20/4197/2023/bg-20-4197-2023.pdf |
| spellingShingle | D. König D. König A. Tagliabue The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes Biogeosciences |
| title | The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| title_full | The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| title_fullStr | The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| title_full_unstemmed | The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| title_short | The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| title_sort | fingerprint of climate variability on the surface ocean cycling of iron and its isotopes |
| url | https://bg.copernicus.org/articles/20/4197/2023/bg-20-4197-2023.pdf |
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