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| Titel |
Impact of atmospheric and terrestrial CO2 feedbacks on fertilization-induced marine carbon uptake |
| VerfasserIn |
A. Oschlies |
| 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 ; 6, no. 8 ; Nr. 6, no. 8 (2009-08-11), S.1603-1613 |
| Datensatznummer |
250003950
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| Publikation (Nr.) |
 copernicus.org/bg-6-1603-2009.pdf |
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| Zusammenfassung |
| The sensitivity of oceanic CO2 uptake to alterations in the marine
biological carbon pump, such as brought about by natural or purposeful ocean
fertilization, has repeatedly been investigated by studies employing
numerical biogeochemical ocean models. It is shown here that the results of
such ocean-centered studies are very sensitive to the assumption made about
the response of the carbon reservoirs on the atmospheric side of the sea
surface. Assumptions made include prescribed atmospheric pCO2, an
interactive atmospheric CO2 pool exchanging carbon with the ocean but not
with the terrestrial biosphere, and an interactive atmosphere that exchanges
carbon with both oceanic and terrestrial carbon pools. The impact of these
assumptions on simulated annual to millennial oceanic carbon uptake is
investigated for a hypothetical increase in the C:N ratio of the biological
pump and for an idealized enhancement of phytoplankton growth. Compared to
simulations with interactive atmosphere, using prescribed atmospheric
pCO2 overestimates the sensitivity of the oceanic CO2 uptake to
changes in the biological pump, by about 2%, 25%, 100%, and >500% on
annual, decadal, centennial, and millennial timescales, respectively. The
smaller efficiency of the oceanic carbon uptake under an interactive
atmosphere is due to the back flux of CO2 that occurs when atmospheric
CO2 is reduced. Adding an interactive terrestrial carbon pool to the
atmosphere-ocean model system has a small effect on annual timescales, but
increases the simulated fertilization-induced oceanic carbon uptake by about
4%, 50%, and 100% on decadal, centennial, and millennial timescales,
respectively, for pCO2 sensitivities of the terrestrial carbon storage
in the middle range of the C4MIP models (Friedlingstein et al., 2006). For
such sensitivities, a substantial fraction of oceanic carbon uptake induced
by natural or purposeful ocean fertilization originates, on timescales longer
than decades, not from the atmosphere but from the terrestrial biosphere. |
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