Climate Change Impacts on Alpine Lakes Summary Introduction.................................................................................................................................... 7 1. Climate change and alpine lakes.......................................................................................... 8 . Global Climate Change ......................................................................................................... 9 . Definitions...................................................................................................................... 9 . Climate.change.in.the.past............................................................................................ 9 . Human.caused.climate.change....................................................................................10 . Consequences.of.present.climate.change...................................................................11 . Future.climate.change..................................................................................................11 Climate change and lakes .................................................................................................. 11 Impacts.on.physical,.chemical.and.biological.lake.parameters...................................12 . Conclusions..................................................................................................................13 . References................................................................................................................... 16 . List.of.figures................................................................................................................20 . List.of.tables.................................................................................................................20 2. Survey on climate change.................................................................................................... 22 . Introduction........................................................................................................................... 23 The past trend ...................................................................................................................... 24 Water.temperatures......................................................................................................24 .. Air.Temperature............................................................................................................29 . Precipitation................................................................................................................. 32 . Transparency................................................................................................................35 . Oxygen.........................................................................................................................36 . Phosphorus..................................................................................................................40 . Chlorophyll.a................................................................................................................ 42 . Phytoplankton.–.Chlorophyceae..................................................................................43 Climate Driven Scenarios ................................................................................................... 44 . Regional.Climatic.Scenarios.in.the.Alpine.Space........................................................44 . Multimodel.Super.Ensemble.Technique.......................................................................45 . Climate.Driven.Alpine.Scenarios..................................................................................45 References ........................................................................................................................... 48 List of figures ....................................................................................................................... 48 List of tables ........................................................................................................................ 49. 2 3. A model ecosystem for small mesotrophic and eutrophic sub-alpine lakes ......... 50 . Model formulation – single layer and spatially homogeneous conditions .....................51 Simulation results for Lake Viverone – homogeneous model .........................................54 Model formulation – two vertical layers ............................................................................59 Simulations for Lake Viverone – Two layer model ............................................................60 Effects of climate and environmental change ..................................................................62 A comment on the use of one- or two-layer models ....................................................... 63 Application of the lake ecosystem models to other lakes .............................................. 63 References ...........................................................................................................................74 List of tables ........................................................................................................................ 74 List of figures .......................................................................................................................74 4. Hydrodynamic model............................................................................................................ 79 . Preface ................................................................................................................................. 79 The hydrodynamic model ...................................................................................................79 ..Adaption.to.alpine.lakes...............................................................................................80 ..The.models.parameterization.and.meteorological.forcing...........................................80 ..Calibrating.the.model.with.an.evolutionary.algorithm..................................................81 . The three pilot sites .............................................................................................................82 ..Lake.Constance:.Data,.parameterization,.and.calibration.results............................... 82 ..Lago.di.Viverone:.Data,.parameterization,.and.calibration.results...............................84 ..Wörthersee:.Data,.parameterization,.and.calibration.results.......................................85 Scenario development ........................................................................................................86 ..Lake.Constance........................................................................................................... 86 ..Lago.di.Viverone...........................................................................................................89 ..Lake.Wörthersee..........................................................................................................90.......................................................................................................... 90 Tracer calculations ..............................................................................................................91.............................................................................................................. Results and Discussion ............................................................................................................................................................................................................ 92 . Results.for.Lake.Constance.........................................................................................92......................................................................................... ..Results.at.Lago.di.Viverone..........................................................................................93.......................................................................................... 93 ..Results.at.Lake.Wörthersee.........................................................................................94......................................................................................... 94 Conclusion ...........................................................................................................................96........................................................................................................................... 96 Appendix to the results of HCILS: Figures ........................................................................97........................................................................ References .........................................................................................................................109......................................................................................................................... List of figures ....................................................................................................................................................................................109...................................................... List of tables ............................................................................................................................................................................................................................................ 115 3 5. Hydrological water balance modelling, isotope investigations of lake circulation and residence time,