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Projected change by the                        projections also suggest an increase in the number,
                                                         frequency and intensity of extreme warm air and water
          end of the century                             events across the region (see review by Di Carlo and
                                                         Otero, 2012).

          Most of the models’ outcomes for the different scenar-  Precipitation (rain and snow) is expected to decrease in
          ios include a rise in air temperature over the Mediter-  the Mediterranean area, particularly in summer, when
          ranean region by the end of the 21st century. Compari-  the risk of drought will be higher. In the A1B scenario,
          sons of the projected temperatures with the averages   precipitation will decrease by 25% in summer and 10%
          for the first half of the 20th century show an increase   in winter by 2100, with major variations between the
          of 2–5°C for the Mediterranean, with a mean of 3.2°C,   southern Mediterranean countries and regions such as
          which is higher than the global average (2.6°C). Climate   Iberia, Anatolia and the Balkans.

                        Table 1. Observed and expected marine climate changes in the Mediterranean
                                   as well as confidence levels (High, medium or low).

           Mediterranean    What is happening  What is likely to happen               References
           Sea                                by the end of the 21st century

                            Surface           Surface temperatures will rise by a further 2.5°C on
                            temperatures have   average by 2100, and intermediate and deep layer
           Temperature                                                                Lionello, 2012
                            risen by roughly 1°C  temperatures will rise as well
                                              (High confidence)

                                              Will tend to increase in surface, intermediate and
                            Increased by 0.05   deep layers; surface salinity could increase by 0.5
                            ppt in intermediate   ppt by 2100 depending on freshwater inputs, ocean   Vargas-Yáñez et
                            and deep layers in   circulation and other factors with a higher increase in   al., 2012
                            the 20th century  the Aegean and Adriatic seas
                                              (Medium confidence)

                                              Temperature and salinity increases would have
                                              opposite effects on sea-level (Low confidence).
                            Mediterranean sea
           Sea-level        levels have been   Ocean temperature-driven sea-level rise during the   EEA Report No
                                              21st century could be between 3 and 61 cm, while
                            rising by 1–3 mm/yr
                                              salinity-driven sea-level change estimates between
                                              -22 and +31 cm.
                            Ocean surface water   The Mediterranean Sea will continue to acidify
                            pH has fallen by 0.1   with increasing CO  emissions. At global level it is
           Sea acidification  pH unit, equivalent   projected to drop another 0.3 to 0.4 units by 2100   Denman et al.,
                            to a 30% increase in   (to a pH less than 7.8)            2011
                            acidity           (Low confidence)

                                              Possible weakening and disruption of the
           Mediterranean    No observed effects   thermohaline circulation            Li et al., 2012 in
           circulation      at the moment                                             Lionello, 2012
                                              (Medium confidence)

                            Impacts on        Expected to increase in the future due to the effects
                            estuarine, beach                                          Critto et al.,
           Coastal erosion  and deltaic coastal   of sea-level rise and storms, particularly in autumn   2012; Sano et
                                              and winter
                            areas, with reduced   (Low confidence)                    al., 2010.
                            sediment deposition

           Upwellings and   No observed effects   Lower intensity                     Lionello, 2012
           current intensity  at the moment   (Low confidence)

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