Assessment of Climate Change for the Baltic Sea Basin

Transcription

1 The BACC Author Team Assessment of Climate Change for the Baltic Sea Basin 4u Springer

2 Contents Preface The BACC Author Team Acknowledgements V VII XIII 1 Introduction and Summary The BACC Approach General Background - The Global Context Climate Change Definition The BACC Initiative and the HELCOM link The Baltic Sea - Geological History and Specifics Geological History of the Baltic Sea Oceanographic Characteristics Climate Characteristics Terrestrial Ecological Characteristics Marine Ecological Characteristics Trends, Jumps and Oscillations - the Problem of Detecting Anthropogenic Climate Change and Attributing it to Causes The Concepts of Formal Detection and Attribution Homogeneity of Data Stationarity of Data - Trends, Oscillations and Jumps Scenarios of Future Climate Change Scenarios - Purpose and Construction Emission Scenarios Scenarios of Anthropogenic Global Climate Change Regional Anthropogenic Climate Change Ongoing Change and Projections for the Baltic Sea Basin - A Summary Recent Climate Change in the Baltic Sea Basin Perspectives for Future Climate Change in the Baltic Sea Basin Changing Terrestrial Ecosystems Changing Marine Ecosystems References 31 2 Past and Current Climate Change The Atmosphere Changes in Atmospheric Circulation Changes in Large-scale Atmospheric Flow Indices Description of Regional Circulation Variations Changes in Surface Air Temperature Annual and Seasonal Area Averaged Time Series Information Drawn from the Longest Instrumental Time Series Temperature Trends in Sub-regions and Relationships with Atmospheric Circulation Mean Daily Maximum and Minimum Temperature Ranges Changes in Seasonality Changes in Precipitation Observed Variability and Trends During the Recent 50 Years Long-term Changes in Precipitation 50 XV

3 XVI Contents Changes in Number of Precipitation Days Interpretation of the Observed Changes in Precipitation Changes in Cloudiness and Solar Radiation Cloudiness and Sunshine Duration Components of the Radiation Budget Changes in Extreme Events Definition of Extremes Temperature Extremes Precipitation Extremes - Droughts and Wet Spells Extreme Winds, Storm Indices, and Impacts of Strong Winds The Hydrological Regime The Water Regime Annual and Seasonal Variation of Total Runoff Regional Variations and Trends Floods Droughts Lakes Ice Regime Ice Events and Ice Thickness in Rivers Ice Events and Ice Thickness in Lakes Ice Conditions in Rivers and Lakes in Finland Snow Cover The Baltic Sea Hydrographic Characteristics Temperature Salinity and Saltwater Inflows Sea Level Main Factors Affecting the Mean Sea Level Changes in the Sea-level from the 1800s to Today Influence of Atmospheric Circulation Sea Ice Ice Extent Length of the Ice Season Ice Thickness Large-scale Atmospheric Forcing on the Ice Conditions Summary Coastal Erosion Western Part of the South Baltic Sea Coast Middle Part of the South Baltic Sea Coast South-eastern Part of the South Baltic Sea Coast Summary Wind Waves Summary of Observed Climate Changes References 112 Projections of Future Anthropogenic Climate Change Introduction to Future Anthropogenic Climate Change Projections Global Anthropogenic Climate Change Global Warming in the 21 st Century Geographical Distribution of Anthropogenic Climate Changes Global Sea Level Rise Global Warming and Sea Level Rise After the Year

4 Contents XVII 3.3 Anthropogenic Climate Change in the Baltic Sea Basin: Projections from Global Climate Models Global Climate Model Experiments Simulation of Present-day Climate from Global Climate Models Projections of Future Climate from Global Climate Models Temperature and Precipitation Atmospheric and Oceanic Circulation Large-scale Wind Probabilistic Projections of Future Climate Using Four Global SRES Scenarios Anthropogenic Climate Change in the Baltic Sea Basin: Projections from Statistical Downscaling Statistical Downscaling Models Projections of Future Climate from Statistical Downscaling Temperature Precipitation Anthropogenic Climate Change in the Baltic Sea Basin: Projections from Regional Climate Models Interpreting Regional Anthropogenic Climate Change Projections Simulation of Present-day Climate from Regional Climate Models Regional Climate Models and Anthropogenic Climate Change Experiments Projections of Future Climate from Regional Climate Models Temperature Precipitation Wind Snow Projections of Future Changes in Climate Variability and Extremes for the Baltic Sea Basin Interpreting Variability and Extremes from Regional Anthropogenic Climate Change Projections Projections of Future Climate Variability and Extremes Temperature Variability and Extremes Precipitation Extremes Wind Extremes Projections of Future Changes in Hydrology for the Baltic Sea Basin Hydrological Models and Anthropogenic Climate Change Interpreting Anthropogenic Climate Change Projections for Hydrology Country Specific Hydrological Assessment Studies Baltic Sea Basinwide Hydrological Assessment Projected Changes in Runoff Projected Changes in Evapotranspiration Synthesis of Projected Future Hydrological Changes Projections of Future Changes in the Baltic Sea Oceanographic Models and Anthropogenic Climate Change Projected Changes in Sea Ice Projected Changes in Sea Surface Temperature and Surface Heat Fluxes Projected Changes in Sea Level and Wind Waves Projected Changes in Salinity and Vertical Overturning Circulation Future Development in Projecting Anthropogenic Climate Changes Summary of Future Anthropogenic Climate Change Projections References 205

5 XVIII Contents Climate-related Change in Terrestrial and Freshwater Ecosystems Introduction Non-Climatic Drivers of Ecosystem Changes Atmospheric Pollutants Land Use Projected Future Changes in European Land Use Land Use Change in the Baltic Sea Basin Projected Combined Impacts of Land Use and Climate Change on Ecosystems Terrestrial Ecosystems Phenology Recent and Historical Impacts Potential Future Impacts Species and Biome Range Boundaries Methodological Remark Recent and Historical Impacts Potential Future Impact Physiological Tolerance and Stress Acclimatisation and Adaptability Plant Resource Allocation Recent and Historical Impacts Potential Future Impacts Ecosystem Productivity and Carbon Storage Recent and Historical Impacts Potential Future Impacts Forest Productivity Forest Resources in the Baltic Sea Basin Objective of the Assessment Sensitivity of Main Tree Species to Climate Change Impact of Climate Change on Forest Growth and Stocking Conclusion with the Management Implications Arctic Ecosystems Introduction Characteristics of Arctic Ecosystems Recent Ecosystem Changes Projected Ecosystem Changes Implications Synthesis - Climate Change Impacts on Terrestrial Ecosystems of the Baltic Sea Basin Freshwater Ecosystems Mechanisms of Response to Climate Change Water Temperature Ice Regime Stratification Hydrology Ecosystem Transformations Impacts of Non-Climatic Anthropogenic Drivers Recent and Historical Impacts Physical Responses Ice Hydrology Chemical Responses Biological Responses 261

6 Contents XIX Potential Future Impacts Physical Responses Hydrology Chemical Responses Biological Responses Synthesis - Climate Change Impacts on Freshwater Ecosystems of the Baltic Sea Basin Nutrient Fluxes from Land Ecosystems to the Baltic Sea Agriculture and Eutrophication Pollution Load to the Baltic Sea Change in Land Use and Agricultural Production Intensity Nutrient Losses from Agricultural Catchments Modelling Approaches Influence of Changes in Land Use and Agricultural Intensity on Nutrient Runoff Potential Future Impact of Climate Change on Nutrient Runoff Measures for Further Decrease of Nutrient Flows to the Baltic Sea Organic Carbon Export from Boreal and Subarctic Catchments Oligotrophic Character of Boreal Watersheds Potential Future Impacts Synthesis - Climate Change Impacts on Nutrient Fluxes from Land Ecosystems to the Baltic Sea Conclusions and Recommendations for Research Summary References 284 Climate-related Marine Ecosystem Change Introduction Sources and Distribution of Nutrients Current Situation Regional Nutrient Trends Contaminants (Chemical Pollution) Chemical Pollution in the Baltic Sea: Past and Present Status Contaminant Loads and their Effects in Baltic Sea Organisms Climate Change Related Implications Bacteria Phytoplankton Physical and Chemical Factors Phytoplankton Trends Diatom Spring Bloom Cyanobacteria Summer Bloom Other Phytoplankton Reactions to Future Anthropogenic Climate Change Zooplankton Benthos Large Scale Benthic Zonation of the Baltic Sea Long-term Trends in the Shallow Benthic Zones Long-term Trends in the Sub-halocline Areas Conceptual Model of Natural and Human-induced Changes in the Sub-halocline Areas of the Baltic Sea Climate Change Related Implications Fish 334

7 XX Contents Baltic Fisheries, their Management and their Effects on Exploited Populations and the Ecosystem Effects of Climate Variability and Anthropogenic Climate Change Marine Mammals Introduction History of Baltic Seals Climate Change Consequences for the Baltic Ice Breeding Seals Harbour Porpoise and Harbour Seal Future Projections Sea Birds Introduction Prehistorical and Historical Bird Communities of the Baltic Sea Impacts of Earlier Climate Variability Anthropogenic Climate Change Impacts on Birds - Predictions Available Studies Fluctuations in Population Levels Phenological Changes Breeding and Population Sizes What Might Happen in the Future? Summary Increase of Nutrients Increase of Temperature Decrease of Salinity References 358 Annexes 379 A.I Physical System Description 379 A. 1.1 Baltic Sea Oceanography 379 A General Features 379 A External Water Budget and Residence Time 382 A.I.1.3 Processes and Patterns of Internal Water Cycle 382 A.1.2 Atmosphere 386 A Atmospheric Circulation 386 A.I.2.2 Surface Air Temperature 388 A.l.2.3 Precipitation 388 A.l.2.4 Clouds 390 A.I.2.5 Surface Global Radiation 390 A.1.3 Hydrology and Land Surfaces 392 A General Characteristics of the Baltic Sea Basin 392 A.l.3.2 River Basins 393 A Lakes and Wetlands 395 A Ice Regimes on Lakes and Rivers 395 A Snow Cover 395 A.2 The Late Quaternary Development of the Baltic Sea 398 A.2.1 Introduction, 398 A.2.2 The Glacial to Late-Glacial Baltic Sea 399"' A.2.3 The Post Glacial Baltic Sea 402 A.3 Ecosystem Description 408 A.3.1 Marine Ecosystem 408 A The Seasonal Cycle of the Marine Ecosystems 408 A External Input 411 A Atmospheric Load 411 A Aquaculture and Eutrophication 420

8 Contents XXI A External Pressures 423 A Sea Traffic 423 A Tourism 425 A.3.2 Terrestrial and Freshwater Ecosystems 431 A Catchment Area of the Baltic Sea 431 A Climate and Terrestrial Ecosystems 432 A Outline of the BIOMASS Forest Growth Model 434 A Outline of the EFISCEN Forest Resource Model 435 A Climate Scenarios Used in SilviStrat Calculations 435 A.4 Observational Data Used 436 A.4.1 Atmosphere 436 A.4.2 Ocean 436 A Hydrographic Characteristics 436 A Sea Level Variability 437 A Optical Properties 437 A.4.3 Runoff 437 A.4.4 Marine Ecosystem Data 438 A HELCOM 438 A ICES. 439 A Other Observational Data used in Chap A.4.5 Observational and Model Data for Anthropogenic Input 440 A.5 Data Homogeneity Issues 441 A.5.1 Homogeneity of Temperature Records 442 A.5.2 Homogeneity of Precipitation Records 442 A.5.3 Homogeneity of Other Climatic Records 443 A.6 Climate Models and Scenarios 443 A.6.1 The SRES Emissions Scenarios 444 A A1FI, AIT and A1B Scenarios 444 A A2 Scenario 444 A Bl Scenario 445 A B2 Scenario 445 A.6.2 Climate Models 445 A Atmosphere-Ocean General Circulation Models (GCMs) 445 A Regional Climate Models (RCMs) 445 A.7 North Atlantic Oscillation and Arctic Oscillation 446 A.8 Statistical Background: Testing for Trends and Change Points (Jumps) 449 A.8.1 A Trend or a Change Point - a Property of a Random Process Generating Limited Time Series 449 A.8.2 Serial Dependency and its Effect on the Accuracy of Conventional Tests 451 A.8.3 Pre-whitening and Monte Carlo Approaches to Overcome the Serial Dependency Problem 453 A.9 References 454 Acronyms and Abbreviations 469