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| Titel |
Calcium carbonate production response to future ocean warming and acidification |
| VerfasserIn |
A. J. Pinsonneault, H. D. Matthews, E. D. Galbraith, A. Schmittner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 6 ; Nr. 9, no. 6 (2012-06-29), S.2351-2364 |
| Datensatznummer |
250007136
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| Publikation (Nr.) |
 copernicus.org/bg-9-2351-2012.pdf |
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| Zusammenfassung |
| Anthropogenic carbon dioxide (CO2) emissions are acidifying the ocean,
affecting calcification rates in pelagic organisms, and thereby modifying
the oceanic carbon and alkalinity cycles. However, the responses of pelagic
calcifying organisms to acidification vary widely between species,
contributing uncertainty to predictions of atmospheric CO2 and the
resulting climate change. At the same time, ocean warming caused by rising
CO2 is expected to drive increased growth rates of all pelagic
organisms, including calcifiers. It thus remains unclear whether
anthropogenic CO2 emissions will ultimately increase or decrease
pelagic calcification rates. Here, we assess the importance of this
uncertainty by introducing a dependence of calcium carbonate (CaCO3)
production on calcite saturation state (ΩCaCO3) in an
intermediate complexity coupled carbon-climate model. In a series of model
simulations, we examine the impact of several variants of this dependence on
global ocean carbon cycling between 1800 and 3500 under two different
CO2 emissions scenarios. Introducing a calcification-saturation state
dependence has a significant effect on the vertical and surface horizontal
alkalinity gradients, as well as on the removal of alkalinity from the ocean
through CaCO3 burial. These changes result in an additional oceanic
uptake of carbon when calcification depends on ΩCaCO3 (of up to
270 Pg C), compared to the case where calcification does not depend on
acidification. In turn, this response causes a reduction of global surface
air temperature of up to 0.4 °C in year 3500. Different versions of the
model produced varying results, and narrowing this range of uncertainty will
require better understanding of both temperature and acidification effects
on pelagic calcifiers. Nevertheless, our results suggest that alkalinity
observations can be used to constrain model results, and may not be
consistent with the model versions that simulated stronger responses of
CaCO3 production to changing saturation state. |
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