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| Titel |
Ocean acidification trends in the North Atlantic: strength and controlling mechanisms |
| VerfasserIn |
Maribel I. Garcia-Ibañez, Patricia Zunino, Friederike Fröb, Noelia M. Fajar, Aida F. Ríos, Herlé Mercier, Are Olsen, Fiz F. Perez |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133076
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| Publikation (Nr.) |
 EGU/EGU2016-13651.pdf |
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| Zusammenfassung |
| The global ocean has absorbed ∼30% of the CO2 emitted to the atmosphere by human
activities (anthropogenic CO2, Cant) between 1750 to the present day. The highest Cant
storage rates have been found in the subpolar North Atlantic. It is very likely that such
accumulation causes chemical changes in seawater CO2 chemistry in this region. Repeated
hydrographic sections provide critically needed data and understanding about changes in the
basin-wide seawater CO2 chemistry over multi-decadal timescales. Here, high-quality
measurements collected at thirteen cruises carried out along the same track between 1981 and
2015 have been used to determine long-term chemical changes in seawater CO2 chemistry
and ocean acidification (OA) in the Irminger and Iceland basins of the North Atlantic Ocean.
Trends were determined for each of the main water masses of the region and are
discussed in the context of the basin-wide circulation. The pH has decreased in all
water masses present in the Irminger and Iceland basins, with greatest changes in
surface and intermediate waters (up to -0.0015 ± 0.0002 pH units⋅yr−1 in surface
waters and up to -0.0013 ± 0.0002 pH units⋅yr−1 in intermediate waters). In order to
disentangle the drivers of the pH changes, we decomposed the trends into their
principal components: changes in temperature, salinity, total alkalinity (AT) and
total dissolved inorganic carbon (both its natural and anthropogenic components).
The Cant increase was identified as the main agent of the pH decline, partially
offset by AT increases. The acidification of intermediate waters caused by Cant
uptake has been reinforced by the aging of these water masses over the period of our
analysis. The pH decrease of the deep overflow waters of the Irminger basin was
similar to that observed in the upper ocean, and was mainly linked to the Cant
increase, thus reflecting the recent contact of these deep waters with the atmosphere. |
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