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

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.

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Biogeochemical response of the Mediterranean Sea to the transient SRES-A2 climate change scenario

Biogeosciences ◽

10.5194/bg-16-135-2019 ◽

2019 ◽

Vol 16 (1) ◽

pp. 135-165 ◽

Cited By ~ 8

Author(s):

Camille Richon ◽

Jean-Claude Dutay ◽

Laurent Bopp ◽

Briac Le Vu ◽

James C. Orr ◽

...

Keyword(s):

Climate Change ◽

Mediterranean Sea ◽

21St Century ◽

Primary Productivity ◽

Net Primary Productivity ◽

Nutrient Concentrations ◽

Change Scenario ◽

Nutrient Inputs ◽

Strait Of Gibraltar ◽

The Mediterranean

Abstract. The Mediterranean region is a climate change hotspot. Increasing greenhouse gas emissions are projected to lead to a substantial warming of the Mediterranean Sea as well as major changes in its circulation, but the subsequent effects of such changes on marine biogeochemistry are poorly understood. Here, our aim is to investigate how climate change will affect nutrient concentrations and biological productivity in the Mediterranean Sea. To do so, we perform transient simulations with the coupled high-resolution model NEMOMED8-PISCES using the high-emission IPCC Special Report on Emissions Scenarios (SRES) A2 socioeconomic scenario and corresponding Atlantic, Black Sea, and riverine nutrient inputs. Our results indicate that nitrate is accumulating in the Mediterranean Sea over the 21st century, while phosphorus shows no tendency. These contrasting changes result from an unbalanced nitrogen-to-phosphorus input from riverine discharge and fluxes via the Strait of Gibraltar, which lead to an expansion of phosphorus-limited regions across the Mediterranean. 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 to separately study the effects of climate and biogeochemical input changes on the future state of the Mediterranean Sea. Our results show that changes in nutrient supply from the Strait of Gibraltar and from rivers and circulation changes linked to climate change may have antagonistic or synergistic effects on nutrient concentrations and surface primary productivity. In some regions such as the Adriatic Sea, half of the biogeochemical changes simulated during the 21st century are linked with external changes in nutrient input, while the other half are linked to climate change. This study is the first to simulate future transient climate change effects on Mediterranean Sea biogeochemistry but calls for further work to characterize effects from atmospheric deposition and to assess the various sources of uncertainty.

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Spring distribution of shelled pteropods across the Mediterranean Sea

10.5194/bg-2020-53 ◽

2020 ◽

Cited By ~ 1

Author(s):

Roberta Johnson ◽

Clara Manno ◽

Patrizia Ziveri

Keyword(s):

Climate Change ◽

Mediterranean Sea ◽

Eastern Mediterranean ◽

Hot Spot ◽

Environmental Parameters ◽

Saturation State ◽

Eastern Mediterranean Sea ◽

The Mediterranean ◽

First Time ◽

Natural Laboratory

Abstract. Shelled pteropods represent an excellent sentinel for indicating exposure to ocean acidification (OA). Here, for the first time, we characterise spring pteropod distribution throughout the Mediterranean Sea, a region that has been identified as a climate change hot-spot. The presence of a west–east natural biogeochemical gradient makes this region a natural laboratory to investigate how the variability in environmental parameters may affect pteropod distribution. Results show that pteropod abundance is significantly higher in the eastern Mediterranean Sea where there is a higher aragonite saturation state (Ωar), showing that distribution is positively correlated with Ωar. We also observed a resilience of pteropods to higher temperatures and low nutrient conditions, including phosphorous limitation. The higher abundance of pteropods in ultra-oligotrophic conditions (eastern Mediterranean Sea) suggests that this organism can play an important role as the prime calcifying zooplankton within specific oligotrophic regions.

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Is coccolithophore distribution in the Mediterranean Sea related to seawater carbonate chemistry?

Ocean Science ◽

10.5194/os-11-13-2015 ◽

2015 ◽

Vol 11 (1) ◽

pp. 13-32 ◽

Cited By ~ 27

Author(s):

A. Oviedo ◽

P. Ziveri ◽

M. Álvarez ◽

T. Tanhua

Keyword(s):

Mediterranean Sea ◽

Hot Spot ◽

Nutrient Concentrations ◽

Carbonate Chemistry ◽

Spatially Distributed ◽

Seasurface Temperature ◽

Seawater Carbonate Chemistry ◽

The Mediterranean ◽

Phytoplankton Group

Abstract. The Mediterranean Sea is considered a "hot spot" for climate change, being characterized by oligotrophic to ultra-oligotrophic waters and rapidly increasing seasurface temperature and changing carbonate chemistry. Coccolithophores are considered a dominant phytoplankton group in these waters. As marine calcifying organisms they are expected to respond to the ongoing changes in seawater carbonate chemistry. We provide here a description of the springtime coccolithophore distribution in the Mediterranean Sea and relate this to a broad set of in situ-measured environmental variables. Samples were taken during the R/V Meteor (M84/3) oceanographic cruise in April 2011, between 0 and 100 m water depth from 28 stations. Total diatom and silicoflagellate cell concentrations are also presented. Our results highlight the importance of seawater carbonate chemistry, especially [CO32−] but also [PO43−] in unraveling the distribution of heterococcolithophores, the most abundant coccolithophore life phase. Holo- and heterococcolithophores respond differently to environmental factors. For instance, changes in heterococcolithophore assemblages were best linked to the combination of [CO32−], pH, and salinity (ρ = 0.57), although salinity might be not functionally related to coccolithophore assemblage distribution. Holococcolithophores, on the other hand, showed higher abundances and species diversity in oligotrophic areas (best fit, ρ = 0.32 for nutrients), thriving in nutrient-depleted waters. Clustering of heterococcolithophores revealed three groups of species sharing more than 65% similarities. These clusters could be assigned to the eastern and western basins and deeper layers (below 50 m), respectively. In addition, the species Gephyrocapsa oceanica, G. muellerae, and Emiliania huxleyi morphotype B/C are spatially distributed together and trace the influx of Atlantic waters into the Mediterranean Sea. The results of the present work emphasize the importance of considering holo- and heterococcolithophores separately when analyzing changes in species assemblages and diversity. Our findings suggest that coccolithophores are a main phytoplankton group in the entire Mediterranean Sea and can dominate over siliceous phytoplankton. They have life stages that are expected to respond differently to the variability in seawater carbonate chemistry and nutrient concentrations.

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Review for Biogeosciences entitled "Biogeochemical response of the Mediterranean Sea to Transient SRES-A2 climate change scenario' by Richon et al.

10.5194/bg-2018-208-rc3 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Climate Change ◽

Mediterranean Sea ◽

Climate Change Scenario ◽

Change Scenario ◽

The Mediterranean

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

10.5194/egusphere-egu2020-18508 ◽

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

Oceans contribute to the removal of 25%-30% of the atmospheric anthropogenic CO2, which increase sea water CO2 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 &#160;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.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 CO2 changes will modify the acidification and its annual cycle from the 1850 period to the end of the 21st century according to the future IPCC SRES-A2. &#160;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 (&#8486;A) and their evolution following a changing climate scenario SRES-A2.

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Is coccolithophore distribution in the Mediterranean Sea related to seawater carbonate chemistry?

Ocean Science Discussions ◽

10.5194/osd-11-613-2014 ◽

2014 ◽

Vol 11 (1) ◽

pp. 613-653 ◽

Cited By ~ 6

Author(s):

A. M. Oviedo ◽

P. Ziveri ◽

M. Álvarez ◽

T. Tanhua

Keyword(s):

Mediterranean Sea ◽

Eastern Mediterranean ◽

Hot Spot ◽

Nutrient Concentrations ◽

Carbonate Chemistry ◽

Levantine Basin ◽

Spatially Distributed ◽

Seawater Carbonate Chemistry ◽

The Mediterranean ◽

Phytoplankton Group

Abstract. The Mediterranean Sea is considered a "hot-spot" for climate change, being characterized by oligotrophic to ultra-oligotrophic waters and rapidly changing carbonate chemistry. Coccolithophores are considered a dominant phytoplankton group in these waters. As a marine calcifying organism they are expected to respond to the ongoing changes in seawater CO2 systems parameters. However, very few studies have covered the entire Mediterranean physiochemical gradients from the Strait of Gibraltar to the Eastern Mediterranean Levantine Basin. We provide here an updated state of knowledge of the coccolithophore distribution in the Mediterranean Sea and relate this to a broad set of in situ measured environmental variables. Samples were taken during the Meteor (M84/3) oceanographic cruise in April 2011, between 0–100 m water depth from 28 stations. Total diatom, dinoflagellate and silicoflagellate cell concentrations are also presented. Our results highlight the importance of seawater carbonate chemistry, especially CO32−, in unraveling the distribution of heterococcolithophores, the most abundant coccolithophore life phase. Holo- and hetero-coccolithophores respond differently to environmental factors. For instance, changes in heterococcolithophore assemblages were best linked to the combination of [CO32−], pH, and salinity (ρ = 0.57) although salinity might be not functionally related to coccolithophore assemblage distribution. Holococcolithophores, on the other hand, were preferentially distributed and showed higher species diversity in oligotrophic areas (Best fit, ρ = 0.32 for nutrients), thriving in nutrient depleted waters. Clustering of heterococcolithophores revealed three groups of species sharing more than 65% similarities. These clusters could be assigned to the eastern and western basins, and deeper layers (below 50 m), respectively. In addition, the species Gephyrocapsa oceanica, G. muellerae and Emiliania huxleyi morphotype B/C are spatially distributed together and trace the influx of Atlantic waters into the Mediterranean Sea. The results of the present work emphasize the importance of considering holo- and hetero-coccolithophores separately when analyzing changes in species assemblages and diversity. Our findings clearly show that coccolithophores are a dominant phytoplankton group in the entire Mediterranean Sea; they have life stages that are expected to respond differently to the variability in seawater carbonate chemistry and nutrient concentrations.

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Geo-Hydrological Events and Temporal Trends in CAPE and TCWV over the Main Cities Facing the Mediterranean Sea in the Period 1979–2018

Atmosphere ◽

10.3390/atmos13010089 ◽

2022 ◽

Vol 13 (1) ◽

pp. 89

Author(s):

Guido Paliaga ◽

Antonio Parodi

Keyword(s):

Mediterranean Sea ◽

Mediterranean Region ◽

Hot Spot ◽

Convective Available Potential Energy ◽

Temporal Trends ◽

Meteorological Variables ◽

Trend Test ◽

Increasing Trend ◽

The Mediterranean ◽

Precipitation Events

The Mediterranean region is regarded as the meeting point between Europe, Africa and the Middle East. Due to favourable climatic conditions, many civilizations have flourished here. Approximately, about half a billion people live in the Mediterranean region, which provides a key passage for trading between Europe and Asia. Belonging to the middle latitude zone, this region experiences high meteorological variability that is mostly induced by contrasting hot and cold air masses that generally come from the west. Due to such phenomenon, this region is subject to frequent intensive precipitation events. Besides, in this complex physiographic and orographic region, human activities have contributed to enhance the geo-hydrologic risk. Further, in terms of climate change, the Mediterranean is a hot spot, probably exposing it to future damaging events. In this framework, this research focuses on the analysis of precipitation related events recorded in the EM–DAT disasters database for the period 1979–2018. An increasing trend emerges in both event records and related deaths. Then a possible linkage with two meteorological variables was investigated. Significant trends were studied for CAPE (Convective Available Potential Energy) and TCWV (Total Column Water Vapor) data, as monthly means in 100 km2 cells for 18 major cities facing the Mediterranean Sea. The Mann–Kendall trend test, Sen’s slope estimation and the Hurst exponent estimation for the investigation of persistency in time series were applied. The research provides new evidence and quantification for the increasing trend of climate related disasters at the Mediterranean scale: recorded events in 1999–2018 are about four times the ones in 1979–1998. Besides, it relates this rise with the trend of two meteorological variables associated with high intensity precipitation events, which shows a statistically significative increasing trend in many of the analysed cities facing the Mediterranean Sea.

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Risk of Tropical Cyclones over the Mediterranean Sea in a Climate Change Scenario

Hurricanes and Climate Change ◽

10.1007/978-0-387-09410-6_13 ◽

2008 ◽

pp. 235-250 ◽

Cited By ~ 1

Author(s):

Miguel Angel Gaertner ◽

Enrique Sánchez ◽

Marta Domínguez ◽

Victoria Gil ◽

Miguel Angel Gaertner

Keyword(s):

Climate Change ◽

Mediterranean Sea ◽

Tropical Cyclones ◽

Climate Change Scenario ◽

Change Scenario ◽

The Mediterranean

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Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

Climate Dynamics ◽

10.1007/s00382-021-05812-x ◽

2021 ◽

Author(s):

Alba de la Vara ◽

William Cabos ◽

Dmitry V. Sein ◽

Claas Teichmann ◽

Daniela Jacob

Keyword(s):

Climate Change ◽

Iberian Peninsula ◽

Mediterranean Sea ◽

Large Scale ◽

Regional Distribution ◽

Coupled Model ◽

Climate Change Signal ◽

The North ◽

The Mediterranean ◽

The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

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Mediterranean climate change projections: an update from CMIP5 and CMIP6.

10.5194/egusphere-egu21-12803 ◽

2021 ◽

Author(s):

Josep Cos ◽

Francisco J Doblas-Reyes ◽

Martin Jury

Keyword(s):

Climate Change ◽

21St Century ◽

Hot Spot ◽

Weighting Scheme ◽

Temperature And Precipitation ◽

High Emission ◽

The Mediterranean ◽

Model Ensembles ◽

Projected Changes ◽

Model Weighting

The Mediterranean has been identified as a climate change hot-spot due to increased warming trends and precipitation decline. Recently, CMIP6 was found to show a higher climate sensitivity than its predecessor CMIP5, potentially further exacerbating related impacts on the Mediterranean region.To estimate the impacts of the ongoing climate change on the region, we compare projections of various CMIP5 and CMIP6 experiments and scenarios. In particular, we focus on summer and winter changes in temperature and precipitation for the 21st century under RCP2.6/SSP1-2.6, RCP4.5/SSP2-4.5 and RCP8.5/SSP5-8.5 as well as the high resolution HighResMIP experiments. Additionally, to give robust estimates of projected changes we apply a novel model weighting scheme, accounting for historical performance and inter-independence of the multi-member multi-model ensembles, using ERA5, JRA55 and WFDE5 as observational reference.&#160;Our results indicate a significant and robust warming over the Mediterranean during the 21st century irrespective of the used ensemble and experiments. Nevertheless, the often attested amplified Mediterranean warming is only found for summer. The projected changes vary between the CMIP5 and CMIP6, with the latter projecting a stronger warming. For the high emission scenarios and without weighting, CMIP5 indicates a warming between 4 and 7.7&#186;C in summer and 2.7 and 5&#186;C in winter, while CMIP6 projects temperature increases between 5.6 and 9.2&#186;C in summer and 3.2 to 6.8&#186;C in winter until 2081-2100 in respect to 1985-2005. In contrast to temperature, precipitation changes show a higher level of uncertainty and spatial heterogeneity. However, for the high emission scenario, a robust decline in precipitation is projected for large parts of the Mediterranean during summer. First results applying the model weighting scheme indicate reductions in CMIP6 and increases in CMIP5 warming trends, thereby reducing differences between the two ensembles.

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