Note: Intro -- Preface -- Acknowledgements -- Contents -- List of Boxes -- 1 Introduction -- 2 The Basis: Past Climate Observations and Methods -- 2.1 Observations of Weather and Climate -- 2.2 Historical Climate Observations -- 2.2.1 Documentary and Early Instrumental Data -- 2.2.2 From National Weather Services to a Global Observing System -- 2.3 Upper-Air and Satellite Observations -- 2.4 Data Dissemination in the Course of Time -- 2.5 Uncertainties in Climatic Data -- 2.5.1 Uncertainties and Errors in Measurement Series -- 2.5.2 Inhomogeneities and Homogenisation -- 2.5.3 The Chain of Uncertainties -- 2.6 Data Products and Dynamical-Statistical Methods -- 2.6.1 Spatial Information and Geostatistical Methods -- 2.6.2 Data Assimilation and Reanalyses -- 2.7 Climate Models -- 2.7.1 Characteristics of Climate Models -- 2.7.2 Types of Climate Models and Experiments -- 2.7.3 Downscaling, Nudging, and Other Techniques -- 2.8 Palaeoclimate Information and Techniques -- 2.8.1 Climate Proxies -- 2.8.2 Problems Arising When Working with Proxies -- 2.8.3 Calibration and Modelling of Proxies -- 2.8.4 Climate Reconstructions -- 2.8.5 Data Assimilation in Palaeoclimatology -- 2.9 Datasets Used in This Book -- 2.9.1 Overview -- 2.9.2 Observations and Reanalyses -- 2.9.3 Model Simulations -- 2.9.4 Reconstructions and Offline Assimilation -- 2.9.5 Conclusions -- 3 The Machinery: Mechanisms Behind Climatic Changes -- 3.1 Basic Climate Physics: The Mean State -- 3.1.1 Energy Budget and Heat Transport -- 3.1.1.1 Global-Mean Fluxes -- 3.1.1.2 Spatial View of Heat Transport -- 3.1.2 The General Circulation of the Atmosphere -- 3.1.2.1 The Zonally Symmetric Circulation -- 3.1.2.2 The Zonally Asymmetric Circulation -- 3.1.2.3 The Weather Scale -- 3.1.2.4 Energy Transport -- 3.1.3 Stratospheric Circulation -- 3.1.3.1 Demarcation and Zonal-Mean Circulation. , 3.1.3.2 The Quasi-Biennial Oscillation (QBO) -- 3.1.3.3 Meridional Circulation and Wave-Mean Flow Interaction -- 3.1.3.4 Sudden Stratospheric Warmings and Downward Propagation -- 3.1.4 The Ocean, Air-Sea and Land-Sea Interactions -- 3.1.4.1 Ocean-Atmosphere Interaction -- 3.1.4.2 Ocean Currents -- 3.1.4.3 Land-Sea Interaction -- 3.1.4.4 Monsoon -- 3.1.4.5 Sea Ice and Snow Cover -- 3.2 Expressions and Mechanisms of Climate Variability -- 3.2.1 Statistical and Physical Perspectives of Climate Variability -- 3.2.2 Overview of Circulation Variability Modes -- 3.2.3 The North Atlantic Oscillation (NAO) -- 3.2.4 Variability Modes in the Pacific and the Southern Hemisphere -- 3.2.4.1 The Pacific-North American Pattern -- 3.2.4.2 The Pacific-South American Pattern and the Southern Annular Mode -- 3.2.5 Extratropical Circulation Variability Modes and the Stratosphere -- 3.2.6 Tropical Variability Modes: El Niño-Southern Oscillation (ENSO) -- 3.2.6.1 The ENSO Phenomenon -- 3.2.6.2 ENSO Mechanisms -- 3.2.6.3 ENSO Variability and ``Flavours'' of ENSO -- 3.2.6.4 ENSO Teleconnections -- 3.2.7 Variability Modes in the Atlantic and Indian Ocean -- 3.2.8 Decadal Climate Variability Modes -- 3.3 Forced Climatic Changes -- 3.3.1 Volcanic Effects -- 3.3.1.1 Direct (Radiative) Effects -- 3.3.1.2 Indirect Dynamical Effects -- 3.3.1.3 Aerosol Size -- 3.3.1.4 Quantification of Past Volcanic Forcing -- 3.3.2 Solar Influences -- 3.3.2.1 Changes in Solar Activity -- 3.3.2.2 Observed Solar Effects -- 3.3.2.3 Possible Mechanisms -- 3.3.2.4 Beyond the Sunspot Cycle -- 3.3.2.5 Time Series of Solar Forcing -- 3.3.3 Well-Mixed Greenhouse Gases -- 3.3.3.1 Mechanism -- 3.3.3.2 Impacts on Future Climate -- 3.3.3.3 Effects of Greenhouse Gases on Past Climate -- 3.3.3.4 Changes in Greenhouse Gas Concentrations Since 1600 -- 3.3.4 Tropospheric Aerosols and Reactive Trace Gases. , 3.3.4.1 Properties of Aerosols -- 3.3.4.2 Sources and Spatial Distribution of Aerosols -- 3.3.4.3 Impacts on Climate -- 3.3.4.4 Tropospheric Trace Gases -- 3.3.5 Land Surface -- 3.3.5.1 Mechanisms -- 3.3.5.2 Climate Impacts and Development of Land Cover Since 1600 -- 3.4 Coupling Between Systems and Feedback Mechanisms -- 3.4.1 Interaction Within the Machinery -- 3.4.2 Feedbacks Involving Water Vapour and Clouds -- 3.4.3 Feedbacks Involving Freezing Water: Arctic Amplification and the Cryosphere -- 3.4.4 Water as a Reactant: The Role of the Hydroxyl Radical -- 3.4.5 Feedbacks Involving Evaporating Water: Land Surface Feedbacks -- 4 Climatic Changes Since 1700 -- 4.1 Climatic Changes of the Past Centuries: An Overview -- 4.1.1 The Last Millennium -- 4.1.2 An Overview of Climatic Changes Since 1700: Brükner's View -- 4.1.3 Climatic Changes Since 1700 in Climate Reconstructions -- 4.1.3.1 Global and Northern Hemisphere Temperature Changes -- 4.1.3.2 Continental Temperature Reconstructions -- 4.1.3.3 Precipitation and Drought Reconstructions -- 4.1.3.4 Sea-Surface Temperature Reconstructions -- 4.1.3.5 Regional Climate: Central Europe and the European Alps -- 4.1.4 Climatic Changes in CCC400 and EKF400 -- 4.1.4.1 Global, Hemisphere and Continental Scales -- 4.1.4.2 Changes in the Zonal-Mean Circulation -- 4.1.4.3 Changes in Regional Circulation Indices -- 4.1.4.4 Changes in Extremes -- 4.1.5 Drivers of Global Climate Since 1600 -- 4.2 The Period from 1700 to 1890: The Little Ice Age -- 4.2.1 Climate of the 18th and 19th Centuries -- 4.2.1.1 Mean Climate of the 1700-1890 Period -- 4.2.1.2 Triggers of the Little Ice Age -- 4.2.2 The Maunder Minimum: A Compelling Case for Solar Forcing? -- 4.2.2.1 The Late Maunder Minimum: Rock Bottom of the Little Ice Age Climate -- 4.2.2.2 The Late Maunder Minimum in EKF400. , 4.2.3 The 1790s: Temporary Warmth and Strong Tropical Circulation -- 4.2.3.1 The Summers of 1800-1804 in Switzerland -- 4.2.3.2 Warming in Europe -- 4.2.3.3 Regional or Global? -- 4.2.3.4 Causes of the 1790s Warmth -- 4.2.4 Tambora Eruption, Dalton Minimum, and the Year Without a Summer of 1816 -- 4.2.4.1 Anatomy of the Year Without a Summer -- 4.2.4.2 Causes -- 4.2.4.3 The Year Without a Summer of 1816 in EKF400 and Early Instrumental Data -- 4.2.4.4 The Mistery Continues -- 4.2.5 The Maximum State of Alpine Glaciers in the 1850s -- 4.2.5.1 A 19th Century View of Glacier Changes -- 4.2.5.2 Causes of the 1850s Glacier Advance -- 4.2.5.3 Climate and Glacier Growth Assessed from HISTALP Data -- 4.2.5.4 Retreat -- 4.2.6 Global Droughts During 1876-1878 and El Niño -- 4.2.6.1 The 1877/1878 Drought in EKF400, CCC400, and 20CR -- 4.2.7 Frequent Flooding in the Central European Alps: 1830-1880s -- 4.2.7.1 The 1868 Flood in 20CR and Instrumental Data -- 4.2.8 The Broad Lines: The Little Ice Age -- 4.3 The Period from 1890 to 1945: Out of the Cold -- 4.3.1 Global Drivers and Global Changes -- 4.3.1.1 Changes in Circulation Indices -- 4.3.2 The Warming of the European Arctic from the 1910s to the 1940s -- 4.3.2.1 Mechanisms of the Early 20th Century Arctic Warming -- 4.3.2.2 The Early 20th Century Arctic Warming in CCC400, 20CR, and REC1 -- 4.3.3 The ``Dust Bowl'' Droughts of the 1930s -- 4.3.3.1 Development and Causes of the Dust Bowl -- 4.3.3.2 The Dust Bowl in CCC400, 20CR, Reconstruction and Upper-Level Data -- 4.3.3.3 Puzzle Solved? -- 4.3.4 Global Climate Anomalies During the 1939-1942 El Niño -- 4.3.4.1 The 1940-1942 Climate Anomaly in REC1, CCC400, and HISTOZ -- 4.3.4.2 Wider Effects of El Niño -- 4.3.5 The Broad Lines: Out of the Cold -- 4.4 The Period from 1945 to 1985: Delusive Stability -- 4.4.1 Global Drivers and Global Changes. , 4.4.2 Changes in Atmospheric Constituents -- 4.4.2.1 Tropospheric Aerosols -- 4.4.2.2 Ozone, Methane and Earth's Changing Oxidation Capacity -- 4.4.2.3 A Thickening Ozone Layer? -- 4.4.3 European Summers of 1945-1949 -- 4.4.3.1 Causes and Mechanisms -- 4.4.3.2 The Droughts in CCC400, 20CR, and REC2 -- 4.4.3.3 The 1947 Heatwaves -- 4.4.4 Sahel Pluvial and Drought -- 4.4.4.1 Causes and Mechanisms of the Drought -- 4.4.4.2 The Sahel Pluvial and Droughts in CCC400, REC2, and ECHAM-HAM Nudged Simulations -- 4.4.5 The Climate Shift of 1976/1977 -- 4.4.6 The Broad Lines: Delusive Stability -- 4.5 The Period Since 1985: Accelerated and Slowed Warming -- 4.5.1 Global Drivers and Global Changes -- 4.5.1.1 Global Warming and More -- 4.5.1.2 Greenhouse Gases and Global Brightening -- 4.5.2 The Ozone Hole -- 4.5.2.1 Ozone Depletion and the Ozone Hole in the CASTRO Simulations -- 4.5.2.2 Effect of the Ozone Hole on Climate -- 4.5.2.3 The Southern Annular Mode -- 4.5.3 Eruption of Pinatubo -- 4.5.3.1 Stratospheric Ozone and Temperatures -- 4.5.3.2 Effects on the Energy Budget and the Water Cycle -- 4.5.3.3 Effects on the Biosphere -- 4.5.3.4 Small Eruptions -- 4.5.4 Warm European Winters, Increased Storminess and Positive NAO in the 1990s -- 4.5.4.1 Winter Storms -- 4.5.4.2 Forced NAO? -- 4.5.5 The El Niño of 1997/1998, Forest Fires and the Atmospheric Brown Cloud -- 4.5.5.1 Forest Fires -- 4.5.5.2 The Atmospheric Brown Cloud -- 4.5.6 Droughts in Australia and the Northern Subtropics -- 4.5.6.1 Subtropical Drought 1998-2004 -- 4.5.6.2 The Millenium Drought in Australia -- 4.5.7 Megaheatwaves -- 4.5.7.1 Record-Breaking Heatwaves in the NCEP/NCAR Reanalysis -- 4.5.7.2 Changes in Heatwaves -- 4.5.8 Recent Arctic Warming -- 4.5.8.1 Record Sea Ice Loss -- 4.5.8.2 Vertical Structure of Temperature and Moisture Changes. , 4.5.8.3 Links with the Extratropics and Atmospheric Circulation.