Acidification in the Mediterranean Sea following a transient climate change scenario simulated with a high-resolution regional model

2020 ◽  
Author(s):  
Jean-Claude Dutay ◽  
James orr ◽  
briac le-vu ◽  
julien palmieri ◽  
camille richon ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Regional Model ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Change Scenario ◽  
Saturation State ◽  
Aragonite Saturation ◽  
The Future ◽  
The Mediterranean ◽  
Ipcc Sres

<p>Oceans contribute to the removal of 25%-30% of the atmospheric anthropogenic CO<sub>2</sub>, which increase sea water CO<sub>2</sub> concentration and acidity, and decrease the Aragonite saturation state that may cause problems for calcium carbonate skeletons of marine species. The Mediterranean Sea is a specific environment with a higher alkalinity and a fast ventilation that is in favor of a more important uptake of  anthropogenic CO2 relatively to global ocean, and an acidification process impacting the whole water. The future acidification of the Mediterranean Sea has not been investigated by regional model yet.</p><p>In this study, we used an eddy-permitting regional model of the Mediterranean Sea (NEMO_MED8) coupled to an oceanic biogeochemical model (PISCES) to evaluate how climate and anthropogenic CO<sub>2</sub> changes will modify the acidification and its annual cycle from the 1850 period to the end of the 21<sup>st</sup> century according to the future IPCC SRES-A2.  Evolution of boundary conditions from Rivers and exchange at the Gibraltar strait are considered. We analyse the relative influence of temperature, salinity, DIC and alkalinity on the mean and the seasonal amplitude of acidity (H+) and aragonite saturation sate (Ω<sub>A</sub>) and their evolution following a changing climate scenario SRES-A2.</p>

scholarly journals Tracking cyclones in regional model data: the future of Mediterranean storms

2005 ◽  
Vol 2 ◽  
pp. 13-19 ◽  
Author(s):  
M. Muskulus ◽  
D. Jacob
Keyword(s):  
Regional Climate ◽  
Regional Model ◽  
Climate Modelling ◽  
High Resolution Data ◽  
International Panel ◽  
The Future ◽  
Precipitation Estimates ◽  
Emissions Scenarios ◽  
The Mediterranean ◽  
Ipcc Sres

Abstract. With the advent of regional climate modelling, there are high-resolution data available for regional climatological change studies. Automatic tracking of cyclones in these datasets encounters problems with high spatial resolution due to cyclone substructure. Watershed segmentation, a technique from image analysis, has been used to obtain estimates for the spatial extent of cyclones, enabling better tracking and precipitation analysis. In this study we have used data from a 0.5° Regional Model (REMO) climatological model run for the period from 1961-2099, following the International Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) B2 forcing. The resulting hourly mean sea level pressure (MSLP) fields have been analysed for cyclone numbers and tracks in the Mediterranean region. According to the results, the total number of cyclones in the Mediterranean seems to be increasing in the future, in spite of a general decrease of the numbers of stronger systems. In Summer, the increase in each gridbox seems to be proportional to the total number of cyclones in that box, whereas in Winter there is a slight proportional decrease. As concerns track properties and precipitation estimates along tracks, no significant change could be detected.

scholarly journals Biogeochemical response of the Mediterranean Sea to the transient SRES–A2 climate change scenario

2018 ◽  
Author(s):  
Camille Richon ◽  
Jean-Claude Dutay ◽  
Laurent Bopp ◽  
Briac Le Vu ◽  
James C. Orr ◽  
...  
Keyword(s):  
Climate Change ◽  
Mediterranean Sea ◽  
Nutrient Limitation ◽  
Mediterranean Region ◽  
Hot Spot ◽  
Nutrient Concentrations ◽  
Change Scenario ◽  
Nutrient Inputs ◽  
The Mediterranean ◽  
Ipcc Sres

Abstract. The Mediterranean region is a climate change hot-spot. Increasing greenhouse gas emissions are projected to lead to a significant warming of Mediterranean Sea waters, as well as major changes in its circulation, but the subsequent effects of such changes on marine biogeochemistry are still poorly understood. Our aim is to investigate the changes in nutrient concentrations and biological productivity in response to climate change in the Mediterranean region. To do so, we perform transient simulations with the coupled high resolution model NEMOMED8/PISCES using the pessimistic IPCC SRES-A2 socio-economic scenario and corresponding Atlantic, Black Sea, and coastal nutrient inputs. Our results indicate that nitrate is accumulating in the Mediterranean Sea over the 21st century, whereas no tendency is found for phosphorus. These contrasted variations result from an unbalanced nitrogen-to-phosphorus input from external sources and lead to changes in phytoplankton nutrient limitation factors. In addition, phytoplankton net primary productivity is reduced by 10 % in the 2090s in comparison to the present state, with reductions of up to 50 % in some regions such as the Aegean Sea as a result of nutrient limitation and vertical stratification. We also perform sensitivity tests in order to study separately the effects of climate and biogeochemical input changes on the Mediterranean future state. This article is a first step in the study of transient climate change effects on the Mediterranean biogeochemistry, but calls for coordinated multi-model efforts to explore the various uncertainty sources of such a future projection.

scholarly journals Quantifying the influence of CO<sub>2</sub> seasonality on future ocean acidification

2015 ◽  
Vol 12 (8) ◽  
pp. 5907-5940
Author(s):  
T. P. Sasse ◽  
B. I. McNeil ◽  
R. J. Matear ◽  
A. Lenton
Keyword(s):  
Ocean Acidification ◽  
North Pacific ◽  
Dissolved Inorganic Carbon ◽  
Marine Ecosystem ◽  
Global Ocean ◽  
Saturation State ◽  
The North ◽  
Data Limitations ◽  
The Future ◽  
The North Pacific

Abstract. Ocean acidification is a predictable consequence of rising atmospheric carbon dioxide (CO2), and is highly likely to impact the entire marine ecosystem – from plankton at the base to fish at the top. Factors which are expected to be impacted include reproductive health, organism growth and species composition and distribution. Predicting when critical threshold values will be reached is crucial for projecting the future health of marine ecosystems and for marine resources planning and management. The impacts of ocean acidification will be first felt at the seasonal scale, however our understanding how seasonal variability will influence rates of future ocean acidification remains poorly constrained due to current model and data limitations. To address this issue, we first quantified the seasonal cycle of aragonite saturation state utilizing new data-based estimates of global ocean surface dissolved inorganic carbon and alkalinity. This seasonality was then combined with earth system model projections under different emissions scenarios (RCPs 2.6, 4.5 and 8.5) to provide new insights into future aragonite under-saturation onset. Under a high emissions scenario (RCP 8.5), our results suggest accounting for seasonality will bring forward the initial onset of month-long under-saturation by 17 years compared to annual-mean estimates, with differences extending up to 35 ± 17 years in the North Pacific due to strong regional seasonality. Our results also show large-scale under-saturation once atmospheric CO2 reaches 486 ppm in the North Pacific and 511 ppm in the Southern Ocean independent of emission scenario. Our results suggest that accounting for seasonality is critical to projecting the future impacts of ocean acidification on the marine environment.

scholarly journals Impact of aragonite saturation state changes on migratory pteropods

2011 ◽  
Vol 279 (1729) ◽  
pp. 732-738 ◽  
Author(s):  
Steeve Comeau ◽  
Jean-Pierre Gattuso ◽  
Anne-Marin Nisumaa ◽  
James Orr
Keyword(s):  
Critical Role ◽  
The Arctic ◽  
Depth Range ◽  
High Latitudes ◽  
Empirical Relationships ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Ecological Changes ◽  
State Changes ◽  
Ipcc Sres

Thecosome pteropods play a key role in the food web of various marine ecosystems and they calcify, secreting the unstable CaCO 3 mineral aragonite to form their shell material. Here, we have estimated the effect of ocean acidification on pteropod calcification by exploiting empirical relationships between their gross calcification rates (CaCO 3 precipitation) and aragonite saturation state Ω a , combined with model projections of future Ω a . These were corrected for modern model-data bias and taken over the depth range where pteropods are observed to migrate vertically. Results indicate large reductions in gross calcification at temperate and high latitudes. Over much of the Arctic, the pteropod Limacina helicina will become unable to precipitate CaCO 3 by the end of the century under the IPCC SRES A2 scenario. These results emphasize concerns over the future of shelled pteropods, particularly L. helicina in high latitudes. Shell-less L. helicina are not known to have ever existed nor would we expect them to survive. Declines of pteropod populations could drive dramatic ecological changes in the various pelagic ecosystems in which they play a critical role.

Carbonate System and Acidification of the Adriatic Sea

2020 ◽  
Author(s):  
Valentina Turk ◽  
Nina Bednarsek ◽  
Jadran Faganeli ◽  
Blaženka Gasparovic ◽  
Michele Giani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Adriatic Sea ◽  
Microbial Community Composition ◽  
Aegean Sea ◽  
Total Alkalinity ◽  
The Black Sea ◽  
Po River ◽  
Saturation State ◽  
Northern Adriatic ◽  
The Mediterranean

&lt;p&gt;Although the marginal seas represent only 7% of the total ocean area, the CO&lt;sub&gt;2&lt;/sub&gt; fluxes are intensive and important for the carbon budget, exposing to an intense process of anthropogenic ocean acidification (OA). A decline in pH, especially in the estuarine waters, results also from the eutrophication-induced acidification. The Adriatic Sea is currently a CO&lt;sub&gt;2 &lt;/sub&gt;sink with an annual flux of approximately -1.2 to -3 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; which is twice as low compared to the net sink rates in the NW Mediterranean (-4 to -5 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;). Based on the comparison of two winter cruises carried out in in the 25-year interval between 1983 and 2008, acidification rate of 0.003 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of &amp;#8722;0.0028 &amp;#177; 0.0003 units pH&lt;sub&gt;T&lt;/sub&gt; yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;) and the surface coastal waters (-0.003 &amp;#177; 0.001 and -0.0044 &amp;#177; 0.00006 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;). The computed Revelle factor for the Adriatic Sea, with the value of about 10, indicates that the buffer capacity is rather high and that the waters should not be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6-2.7 mM) is in the upper range of TA measured in the Mediterranean Sea because riverine inputs transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol yr&lt;sup&gt;-1&lt;/sup&gt;), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60% of the TA inflow into the Adriatic Sea is attributed to the Po river discharge with TA of ~3 mM and TA decreases with increasing salinity. Saturation state indicates that the waters of the Adriatic are supersaturated with respect to calcite (&amp;#937;&lt;sub&gt;Ca&lt;/sub&gt;) and aragonite (&amp;#937;&lt;sub&gt;Ar&lt;/sub&gt;) throughout the year. However, saturation states are considerably lower in the bottom water layers, due to the prevalence of benthic remineralization processes in the stratification period. The seasonal changes of the chemical and environmental conditions and relatively small size of the Adriatic Sea area the microbial community composition, function (growth, enzymatic activity) and carbon and nitrogen biogeochemical cycles. Significant effects on calcifying organisms and phytoplankton are expected while the effects of possible OA on microbially-driven processes are not known yet.&lt;/p&gt;

Vanadium behaviour in the global ocean and in the Mediterranean sea

1987 ◽  
Vol 21 (1) ◽  
pp. 51-74 ◽  
Author(s):  
C Jeandel ◽  
M Caisso ◽  
J.F Minster
Keyword(s):  
Mediterranean Sea ◽  
Global Ocean ◽  
The Mediterranean

scholarly journals Characterisation of extreme events waves in marine ecosystems: the case of Mediterranean Sea

2020 ◽  
Author(s):  
Valeria Di Biagio ◽  
Gianpiero Cossarini ◽  
Stefano Salon ◽  
Cosimo Solidoro
Keyword(s):  
Cluster Analysis ◽  
Mediterranean Sea ◽  
Extreme Events ◽  
Marine Ecosystems ◽  
Horizontal Resolution ◽  
Ecosystem Functions ◽  
Biogeochemical Model ◽  
Open Sea ◽  
Basin Scale ◽  
The Mediterranean

Abstract. We propose a new method to identify and characterise the occurrence of prolonged extreme events in marine ecosystems on the basin scale. There is a growing interest about events that can affect ecosystem functions and services in a changing climate. Our method identifies extreme events as peak occurrences over 99th percentile thresholds computed from local time series and defines an Extreme Events Wave (EEW) as a connected region including these events. The EEWs are characterised by a set of novel indexes, referred to initiation, extent, duration and strength. The indexes, associated to the areas covered by each EEW, are then statistically analysed to highlight the main features of the EEWs on the considered domain. We applied the method to the winter-spring daily chlorophyll field of a validated multidecadal hindcast provided by a coupled hydrodynamic-biogeochemical model of the Mediterranean open-sea ecosystem, with 1/12° horizontal resolution. This allowed to identify the maxima of chlorophyll as exceptionally high and prolonged blooms and to characterise their phenomenology in the period 1994–2012. A fuzzy k-means cluster analysis on the EEWs indexes provided a bio-regionalisation of the Mediterranean Sea associated to the occurrence of chlorophyll EEWs with different regimes.

scholarly journals Oxygen budget of the north-western Mediterranean deep- convection region

2021 ◽  
Vol 18 (3) ◽  
pp. 937-960
Author(s):  
Caroline Ulses ◽  
Claude Estournel ◽  
Marine Fourrier ◽  
Laurent Coppola ◽  
Fayçal Kessouri ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Mediterranean Sea ◽  
Atmospheric Oxygen ◽  
Deep Convection ◽  
Western Mediterranean ◽  
Biogeochemical Model ◽  
The North ◽  
Oxygen Budget ◽  
The Mediterranean ◽  
North Western

Abstract. The north-western Mediterranean deep convection plays a crucial role in the general circulation and biogeochemical cycles of the Mediterranean Sea. The DEWEX (DEnse Water EXperiment) project aimed to better understand this role through an intensive observation platform combined with a modelling framework. We developed a three-dimensional coupled physical and biogeochemical model to estimate the cycling and budget of dissolved oxygen in the entire north-western Mediterranean deep-convection area over the period September 2012 to September 2013. After showing that the simulated dissolved oxygen concentrations are in a good agreement with the in situ data collected from research cruises and Argo floats, we analyse the seasonal cycle of the air–sea oxygen exchanges, as well as physical and biogeochemical oxygen fluxes, and we estimate an annual oxygen budget. Our study indicates that the annual air-to-sea fluxes in the deep-convection area amounted to 20 molm-2yr-1. A total of 88 % of the annual uptake of atmospheric oxygen, i.e. 18 mol m−2, occurred during the intense vertical mixing period. The model shows that an amount of 27 mol m−2 of oxygen, injected at the sea surface and produced through photosynthesis, was transferred under the euphotic layer, mainly during deep convection. An amount of 20 mol m−2 of oxygen was then gradually exported in the aphotic layers to the south and west of the western basin, notably, through the spreading of dense waters recently formed. The decline in the deep-convection intensity in this region predicted by the end of the century in recent projections may have important consequences on the overall uptake of atmospheric oxygen in the Mediterranean Sea and on the oxygen exchanges with the Atlantic Ocean, which appear necessary to better quantify in the context of the expansion of low-oxygen zones.

Sign in / Sign up

Export Citation Format

Share Document