Transient climate change scenario simulation of the Mediterranean Sea for the twenty-first century using a high-resolution ocean circulation model

A scenario of the Mediterranean Sea is performed for the twenty-first century based on an ocean modelling approach. A climate change IPCC-A2 scenario run with an atmosphere regional climate model is used to force a Mediterranean Sea high-resolution ocean model over the 1960–2099 period. For comparison, a control simulation as long as the scenario has also been carried out under present climate fluxes. This control run shows air–sea fluxes in agreement with observations, stable temperature and salinity characteristics and a realistic thermohaline circulation simulating the different intermediate and deep water masses described in the literature. During the scenario, warming and saltening are simulated for the surface (+3.1°C and + 0.48 psu for the Mediterranean Sea at the end of the twenty-first century) and for the deeper layers (+1.5°C and + 0.23 psu on average). These simulated trends are in agreement with observed trends for the Mediterranean Sea over the last decades. In addition, the Mediterranean thermohaline circulation (MTHC) is strongly weakened at the end of the twenty-first century. This behaviour is mainly due to the decrease in surface density and so the decrease in winter deep-water formation. At the end of the twenty-first century, the MTHC weakening can be evaluated as −40% for the intermediate waters and −80% for the deep circulation with respect to present-climate conditions. The characteristics of the Mediterranean Outflow Waters flowing into the Atlantic Ocean are also strongly influenced during the scenario.

[1]  R. Huang,et al.  Real Freshwater Flux as a Natural Boundary Condition for the Salinity Balance and Thermohaline Circulation Forced by Evaporation and Precipitation , 1993 .

[2]  Wolfgang Roether,et al.  Recent changes in deep water formation and spreading in the eastern Mediterranean Sea: a review , 1999 .

[3]  Thomas F. Stocker,et al.  Influence of CO2 emission rates on the stability of the thermohaline circulation , 1997, Nature.

[4]  P. Jones,et al.  REPRESENTING TWENTIETH CENTURY SPACE-TIME CLIMATE VARIABILITY. , 1998 .

[5]  U. Cubasch,et al.  Regional climate changes as simulated in time-slice experiments , 1995 .

[6]  S. Castellari,et al.  Simulation of water mass formation processes in the Mediterranean Sea: Influence of the time frequency of the atmospheric forcing , 2000 .

[7]  George L. Pickard,et al.  Descriptive Physical Oceanography: An Introduction , 1963 .

[8]  Elizabeth C. Kent,et al.  New Insights into the Ocean Heat Budget Closure Problem from Analysis of the SOC Air–Sea Flux Climatology , 1999 .

[9]  M. Déqué,et al.  Anthropogenic climate change over the Mediterranean region simulated by a global variable resolution model , 2003 .

[10]  Gurvan Madec,et al.  Salt conservation, free surface, and varying levels: A new formulation for ocean general circulation models , 2000 .

[11]  M. Déqué,et al.  Simulation des changements climatiques au cours du XXIe siècle incluant l'ozone stratosphérique , 2002 .

[12]  E. Tziperman,et al.  A Study of Water Mass Transformation in the Mediterranean Sea: Analysis of Climatological Data and a Simple Three-Box Model , 1994 .

[13]  Jean-Michel Brankart,et al.  Abrupt Cooling of the Mediterranean Levantine Intermediate Water at the Beginning of the 1980s: Observational Evidence and Model Simulation , 2001 .

[14]  G. Wüst.  On the vertical circulation of the Mediterranean Sea , 1961 .

[15]  K. Haines,et al.  Frictional sinking of the dense water overflow in a z‐Coordinate OGCM of the Mediterranean Sea , 2000 .

[16]  Bruno Blanke,et al.  Variability of the Tropical Atlantic Ocean Simulated by a General Circulation Model with Two Different Mixed-Layer Physics , 1993 .

[17]  Thomas M. Smith,et al.  Reconstruction of Historical Sea Surface Temperatures Using Empirical Orthogonal Functions , 1996 .

[18]  Eli Tziperman,et al.  On the Role of Interior Mixing and Air-Sea Fluxes in Determining the Stratification and Circulation of the Oceans , 1986 .

[19]  John Marshall,et al.  Open‐ocean convection: Observations, theory, and models , 1999 .

[20]  F. Chauvin,et al.  Sensitivity of the hydrological cycle to increasing amounts of greenhouse gases and aerosols , 2002 .

[21]  Richard G. Jones,et al.  Validation and analysis of regional present-day climate and climate change simulations over Europe , 1998 .

[22]  Dimitrios Georgopoulos,et al.  Recent Changes in Eastern Mediterranean Deep Waters , 1996, Science.

[23]  V. Canuto,et al.  Modeling ocean deep convection , 2004 .

[24]  K. Haines,et al.  Seasonal and Interannual Variability in a Model of the Mediterranean under Derived Flux Forcing , 2000 .

[25]  J. Bethoux.  Mediterranean sapropel formation, dynamic and climatic viewpoints , 1993 .

[26]  M. Déqué,et al.  High resolution climate simulation over Europe , 1995 .

[27]  G. Müller,et al.  The Scientific Basis , 1995 .

[28]  K. Haines,et al.  The general circulation of the Mediterranean Sea from a 100‐year simulation , 1998 .

[29]  Uwe Send,et al.  Observations of Deep Convection in the Gulf of Lions, Northern Mediterranean, during the Winter of 1991/92 , 1996 .

[30]  R. Thorpe,et al.  Modelling the sensitivity of Mediterranean Outflow to anthropogenically forced climate change , 2000 .

[31]  David A. Robinson,et al.  Improved simulations of snow extent in the second phase of the Atmospheric Model Intercomparison Project (AMIP-2) , 2003 .

[32]  A. Arakawa.  Design of the UCLA general circulation model , 1972 .

[33]  P. Delecluse,et al.  A Three-Dimensional Numerical Study of Deep-Water Formation in the Northwestern Mediterranean Sea , 1991 .

[34]  S. Matthiesen,et al.  A hydraulic box model study of the Mediterranean response to postglacial sea-level rise , 2003 .

[35]  Richard A. Wood,et al.  Global Climatic Impacts of a Collapse of the Atlantic Thermohaline Circulation , 2002 .

[36]  Gösta Walin,et al.  On the relation between sea‐surface heat flow and thermal circulation in the ocean , 1982 .

[37]  K. Haines,et al.  Stability of the Mediterranean's thermohaline circulation under modified surface evaporative fluxes , 2002 .

[38]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[39]  K. Haines,et al.  Modeling the dispersal of Levantine Intermediate Water and its role in Mediterranean deep water formation , 1996 .

[40]  D. Kamykowski,et al.  Spatio-temporal and process-oriented views of nitrite in the world ocean as recorded in the historical data set , 1991 .

[41]  H. Douville,et al.  Importance of vegetation feedbacks in doubled‐CO2 climate experiments , 2000 .

[42]  C. Garrett.  The role of the Strait of Gibraltar in the evolution of Mediterranean water, properties and circulation , 1996 .

[43]  G. Etiope,et al.  Warming, salting and origin of the Tyrrhenian Deep Water , 2002 .

[44]  C. Mertens,et al.  Interannual Variability of Deep-Water Formation in the Northwestern Mediterranean , 1998 .

[45]  A. Lascaratos,et al.  Dense water formation in the Aegean Sea: Numerical simulations during the Eastern Mediterranean Transient : Physical and Biochemical Evolution of the Eastern Mediterranean in the '90s (PBE) , 2003 .

[46]  R. Döscher,et al.  The Baltic haline conveyor belt or the overturning circulation and mixing in the Baltic. , 2004, Ambio.

[47]  Chris Garrett,et al.  Heat flux parameterizations for the Mediterranean sea : the role of atmospheric aerosols and constraints from the water budget , 1994 .

[48]  Jesper Heile Christensen,et al.  Daily precipitation statistics in regional climate models: Evaluation and intercomparison for the European Alps , 2003 .

[49]  Romain Bourdallé-Badie,et al.  Meddies in the Mercator North Atlantic and Mediterranean Sea eddy‐resolving model , 2005 .

[50]  Patrick Marchesiello,et al.  Thermal forcing for a global ocean circulation model using a three-year climatology of ECMWF analyses , 1995 .

[51]  S. Josey.  Changes in the heat and freshwater forcing of the eastern Mediterranean and their influence on deep water formation , 2003 .

[52]  E. Rohling,et al.  Modeling the paleocirculation of the Mediterranean: The Last Glacial Maximum and the Holocene with emphasis on the formation of sapropel S 1 , 1998 .

[53]  E. Özsoy,et al.  A synthesis of the Levantine Basin circulation and hydrography, 1985–1990 , 1993 .

[54]  Walter H. F. Smith,et al.  Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings , 1997 .

[55]  P. Jones,et al.  Representing Twentieth-Century Space–Time Climate Variability. Part I: Development of a 1961–90 Mean Monthly Terrestrial Climatology , 1999 .

[56]  J. Bethoux,et al.  Budgets of th~ Medit_erranean Sea. Their depenqance on the local climate and on the characteristics of the Atlantic waters· , 1979 .

[57]  Harry L. Bryden,et al.  Steady two-layer exchange through the Strait of Gibraltar , 1991 .

[58]  G. Budillon,et al.  Evolution of dynamics in the eastern Mediterranean affecting water mass structures and properties in the Ionian and Adriatic Seas , 2003 .

[59]  D. Iudicone,et al.  Eastern Mediterranean Transient studied with Lagrangian diagnostics applied to a Mediterranean OGCM forced by satellite SST and ECMWF wind stress for the years 1988–1993 , 2003 .

[60]  F. Giorgi,et al.  Introduction to special section : Regional climate modeling revisited , 1999 .

[61]  Uwe Send,et al.  Representation of convective plumes by vertical adjustment , 1996 .

[62]  B. Barnier,et al.  A new analysis of hydrographic data in the Atlantic and its application to an inverse modeling study , 1998 .

[63]  John G. Adair,et al.  An introduction to the Special Issue , 2005 .

[64]  J. Reid.  On the contribution of the Mediterranean Sea outflow to the Norwegian-Greenland Sea , 1979 .

[65]  M. Déqué,et al.  The ARPEGE/IFS atmosphere model: a contribution to the French community climate modelling , 1994 .

[66]  Aniello Russo,et al.  The Adriatic Sea general circulation. Part I: Air-sea interactions and water mass structure , 1997 .

[67]  S. Somot.  Modélisation climatique du Bassin méditerranéen : variabilité et scénarios de changement climatique , 2005 .

[68]  E. Tragou,et al.  A mixed-layer study of the formation of Levantine Intermediate Water , 1993 .

[69]  D. Dokken,et al.  Climate change 2001 , 2001 .

[70]  G. Korres,et al.  The Ocean Response to Low-Frequency Interannual Atmospheric Variability in the Mediterranean Sea. Part I: Sensitivity Experiments and Energy Analysis , 2000 .

[71]  B. Gentili,et al.  Warming and freshwater budget change in the Mediterranean since the 1940s, their possible relation to the greenhouse effect , 1998 .

[72]  W. Collins,et al.  The NCEP–NCAR 50-Year Reanalysis: Monthly Means CD-ROM and Documentation , 2001 .

[73]  P. Delecluse,et al.  Large-Scale Preconditioning of Deep-Water Formation in the Northwestern Mediterranean Sea , 1996 .

[74]  Eli Tziperman,et al.  Rates of Water Mass Formation in the North Atlantic Ocean , 1992 .

[75]  B. Klein,et al.  Accelerated oxygen consumption in eastern Mediterranean deep waters following the recent changes in thermohaline circulation , 2003 .

[76]  T. McDougall,et al.  Minimal Adjustment of Hydrographic Profiles to Achieve Static Stability , 1995 .

[77]  Michel Crépon,et al.  The dynamics of the Sicily Strait: a comprehensive study from observations and models , 2004 .

[78]  B. Gentili,et al.  Warming trend in the western Mediterranean deep water , 1990, Nature.

[79]  T. Wigley,et al.  Statistical downscaling of general circulation model output: A comparison of methods , 1998 .

[80]  F. Giorgi,et al.  PRUDENCE employs new methods to assess European climate change , 2002 .

[81]  Pier Luigi Vidale,et al.  Evaluation of water and energy budgets in regional climate models applied over Europe , 2004 .

[82]  Medoc Group.  Observation of Formation of Deep Water in the Mediterranean Sea, 1969 , 1970, Nature.

[83]  H. Bryden,et al.  Man-induced salinity and temperature increases in western Mediterranean deep water. (Reannouncement with new availability information) , 1992 .

[84]  A. Lascaratos.  Estimation of deep and intermediate water mass formation rates in the Mediterranean Sea , 1993 .

[85]  Pierre-Yves Le Traon,et al.  Sea level variations and their dependency on meteorological and hydrological forcing: Analysis of altimeter and surface data for the Black Sea , 2000 .

[86]  B. Klein,et al.  The large deep water transient in the Eastern Mediterranean , 1999 .

[87]  J. Chanut.  Paramétrisation de la restratification après convection profonde en mer du Labrador , 2003 .

[88]  B. Dickson,et al.  A change in the freshwater balance of the Atlantic Ocean over the past four decades , 2003, Nature.

[89]  S. Manabe,et al.  The rôle of thermohaline circulation in climate , 1999 .

[90]  Gurvan Madec.  La formation d'eau profonde et son impact sur la circulation regionale en mediterranee occidentale : une approche numerique , 1990 .

[91]  M. Crépon,et al.  The effect of thermohaline forcing variability on deep water formation in the western Mediterranean Sea: a high-resolution three-dimensional numerical study , 1991 .

[92]  M. Lozier,et al.  On the warming and salinification of the Mediterranean outflow waters in the North Atlantic , 2004 .

[93]  P. Delecluse,et al.  OPA 8.1 Ocean General Circulation Model reference manual , 1998 .