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| Titel |
Spatiotemporal variability and long-term trends of ocean acidification in the California Current System |
| VerfasserIn |
C. Hauri, N. Gruber, M. Vogt, S. C. Doney, R. A. Feely, Z. Lachkar, A. Leinweber, A. M. P. McDonnell, M. Munnich, G.-K. Plattner |
| 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 ; 10, no. 1 ; Nr. 10, no. 1 (2013-01-14), S.193-216 |
| Datensatznummer |
250017467
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| Publikation (Nr.) |
 copernicus.org/bg-10-193-2013.pdf |
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| Zusammenfassung |
| Due to seasonal upwelling, the upper ocean waters of the California Current
System (CCS) have a naturally low pH and aragonite saturation state
(Ωarag), making this region particularly prone to the effects
of ocean acidification. Here, we use the Regional Oceanic Modeling System
(ROMS) to conduct preindustrial and transient (1995–2050) simulations of
ocean biogeochemistry in the CCS. The transient simulations were forced with
increasing atmospheric pCO2 and increasing oceanic dissolved inorganic
carbon concentrations at the lateral boundaries, as projected by the NCAR CSM
1.4 model for the IPCC SRES A2 scenario. Our results show a large seasonal
variability in pH (range of ~ 0.14) and Ωarag
(~ 0.2) for the nearshore areas (50 km from shore). This variability is created by the
interplay of physical and biogeochemical processes. Despite this large
variability, we find that present-day pH and Ωarag have
already moved outside of their simulated preindustrial variability envelopes
(defined by ±1 temporal standard deviation) due to the rapidly increasing
concentrations of atmospheric CO2. The nearshore surface pH of the
northern and central CCS are simulated to move outside of their present-day
variability envelopes by the mid-2040s and late 2030s, respectively. This
transition may occur even earlier for nearshore surface Ωarag,
which is projected to depart from its present-day variability envelope by
the early- to mid-2030s. The aragonite saturation horizon of the
central CCS is projected to shoal into the upper 75 m within the next 25
yr, causing near-permanent undersaturation in subsurface waters. Due to the
model's overestimation of Ωarag, this transition may occur
even earlier than simulated by the model. Overall, our study shows that the
CCS joins the Arctic and Southern oceans as one of only a few known ocean
regions presently approaching the dual threshold of widespread and
near-permanent undersaturation with respect to aragonite and a departure from its
variability envelope. In these regions, organisms may be forced to rapidly
adjust to conditions that are both inherently chemically challenging and also
substantially different from past conditions. |
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