Time variability of the north-western Mediterranean Sea pH over 1995–2011

Yao, Koffi Marcellin; Marcou, Olivier; Goyet, Catherine; Guglielmi, Véronique; Touratier, Franck

doi:10.1016/j.marenvres.2016.02.016

Cited by 32 publications

(15 citation statements)

References 62 publications

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“…At the end of the century, the model from Caldeira & Wickett (2003) predicted an increased acidification with a pH decrease between 0.3 and 0.4 pH unit. Similarly, Géri et al (2014) and Yao et al (2016) predicted the same range of pH decrease (0.3-0.4 pH unit) in the northwestern part of the Mediterranean Sea. Table 3 shows the results of calcium carbonate ions (calcite and aragonite) saturations at the base of the mixed layer depth, for both the Western and Eastern basins.…”

Section: Acidification Estimates Of the Mediterranean Seamentioning

confidence: 60%

Thermodynamic Forecasts of the Mediterranean Sea Acidification

et al. 2016

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Anthropogenic CO2 is a major driver of the present ocean acidification. This latter is threatening the marine ecosystems and has been identified as a major environmental and economic menace. This study aims to forecast from the thermodynamic equations, the acidification variation (ΔpH) of the Mediterranean waters over the next few decades and beyond this century. In order to do so, we calculated and fitted the theoretical values based upon the initial conditions from data of the 2013 MedSeA cruise. These estimates have been performed both for the Western and for the Eastern basins based upon their respective physical (temperature and salinity) and chemical (total alkalinity and total inorganic carbon) properties. The results allow us to point out four tipping points, including one when the Mediterranean Sea waters would become acid (pH<7). In order to provide an associated time scale to the theoretical results, we used two of the IPCC (2007) atmospheric CO2 scenarios. Under the most optimistic scenario of the “Special Report: Emissions Scenarios” (SRES) of the IPCC (2007), the results indicate that in 2100, pH may decrease down to 0.245 in the Western basin and down to 0.242 in the Eastern basin (compared to the pre-industrial pH). Whereas for the most pessimistic SRES scenario of the IPCC (2007), the results for the year 2100, forecast a pH decrease down to 0.462 and 0.457, for the Western and for the Eastern basins, respectively. Acidification, which increased unprecedentedly in recent years, will rise almost similarly in both Mediterranean basins only well after the end of this century. These results further confirm that both basins may become undersaturated (< 1) with respect to calcite and aragonite (at the base of the mixed layer depth), only in the far future (in a few centuries).

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Section: Acidification Estimates Of the Mediterranean Seamentioning

confidence: 60%

Thermodynamic Forecasts of the Mediterranean Sea Acidification

et al. 2016

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“…1), was estimated at −0.003 ± 0.001 units pH SW yr −1 from 1995 to 2011 (Marcellin Yao et al, 2016). At DYFAMED, warming contributed approximately 30 % to the acidification rate and the remaining 70 % was attributed to anthropogenic CO 2 (Marcellin Yao et al, 2016).…”

Section: Discussionmentioning

confidence: 98%

“…For example, estimates of change in pH of bottom waters since the preindustrial era range between −0.005 and −0.06 (Palmiéri et al, 2015) and up to as much as −0.14 for full profile estimates (Touratier and Goyet, 2011). Techniques for estimating ocean acidification in the Mediterranean Sea thus far include the following: (1) hind-casting, using highresolution regional circulation models (Palmiéri et al, 2015), the TrOCA approach as applied to cruise-based profile data (Krasakopoulou et al, 2011;Touratier and Goyet, 2011;Touratier et al, 2016), and others (Howes et al, 2015); (2) partially reconstructed time series (Marcellin Yao et al, 2016); (3) comparative study periods (Luchetta et al, 2010;Meier et al, 2014); and (4) sensor-based observations over a short study period (Flecha et al, 2015). Ocean acidification time series of consistent sampling over many years are lacking for the Mediterranean Sea (The MerMex Group, 2011), particularly along the coast where river discharge influences the carbonate system (Ingrosso et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

et al. 2017

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Abstract. Coastal time series of ocean carbonate chemistry are critical for understanding how global anthropogenic change manifests in near-shore ecosystems. Yet, they are few and have low temporal resolution. At the time series station Point B in the northwestern Mediterranean Sea, seawater was sampled weekly from 2007 through 2015, at 1 and 50 m, and analyzed for total dissolved inorganic carbon (C T ) and total alkalinity (A T ). Parameters of the carbonate system such as pH (pH T , total hydrogen ion scale) were calculated and a deconvolution analysis was performed to identify drivers of change. The rate of surface ocean acidification was −0.0028 ± 0.0003 units pH T yr −1 . This rate is larger than previously identified open-ocean trends due to rapid warming that occurred over the study period (0.072 ± 0.022 • C yr −1 ). The total pH T change over the study period was of similar magnitude as the diel pH T variability at this site. The acidification trend can be attributed to atmospheric carbon dioxide (CO 2 ) forcing (59 %, 2.08 ± 0.01 ppm CO 2 yr −1 ) and warming (41 %). Similar trends were observed at 50 m but rates were generally slower. At 1 m depth, the increase in atmospheric CO 2 accounted for approximately 40 % of the observed increase in C T (2.97 ± 0.20 µmol kg −1 yr −1 ). The remaining increase in C T may have been driven by the same unidentified process that caused an increase in A T (2.08 ± 0.19 µmol kg −1 yr −1 ). Based on the analysis of monthly trends, synchronous increases in C T and A T were fastest in the spring-summer transition. The driving process of the interannual increase in A T has a seasonal and shallow component, which may indicate riverine or groundwater influence. This study exemplifies the importance of understanding changes in coastal carbonate chemistry through the lens of biogeochemical cycling at the land-sea interface. This is the first coastal acidification time series providing multiyear data at high temporal resolution. The data confirm rapid warming in the Mediterranean Sea and demonstrate coastal acidification with a synchronous increase in total alkalinity.

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“…All of these values are, however, almost twice as high as the peak-to-peak amplitude of DIC determined in this study. This may be attributed to either the longer timespan of the current data set compared to Copin-Montégut and , thereby including interannual variability, or to the different methodology this study uses to determine the seasonal mean compared to Gemayel et al [2015] and Marcellin Yao et al [2016].…”

Section: Seasonal Variability At the Dyfamed Stationmentioning

confidence: 99%

Attributing seasonal pH variability in surface ocean waters to governing factors

Hagens

Middelburg

2016

Geophysical Research Letters

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On‐going ocean acidification and increasing availability of high‐frequency pH data have stimulated interest to understand seasonal pH dynamics in surface waters. Here we show that it is possible to accurately reproduce observed pH values by combining seasonal changes in temperature (T), dissolved inorganic carbon (DIC), and total alkalinity (TA) from three time series stations with novel pH sensitivity factors. Moreover, we quantify the separate contributions of T, DIC, and TA changes to winter‐to‐summertime differences in pH, which are in the ranges of −0.0334 to −0.1237, 0.0178 to 0.1169, and −0.0063 to 0.0234, respectively. The effects of DIC and temperature are therefore largely compensatory, and are slightly tempered by changes in TA. Whereas temperature principally drives pH seasonality in low‐latitude to midlatitude systems, winter‐to‐summer DIC changes are most important at high latitudes. This work highlights the potential of pH sensitivity factors as a tool for quantifying the driving mechanisms behind pH changes.

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Time variability of the north-western Mediterranean Sea pH over 1995–2011

Cited by 32 publications

References 62 publications

Thermodynamic Forecasts of the Mediterranean Sea Acidification

Thermodynamic Forecasts of the Mediterranean Sea Acidification

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Attributing seasonal pH variability in surface ocean waters to governing factors

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