Past Climate Variability in South America and Surrounding Regions (eBook)

Acknowledgments 6
Preface 7
Contents 9
Contributors 12
Part I Can We Draw a Robust Picture of Last Glacial Maximum Climate Conditions in South America? 17
1 Moisture Pattern During the Last Glacial Maximum in South America 18
1.1 Introduction 19
1.2 Modern Climate 21
1.3 Evidence of Regional Paleoclimatic Changes 25
1.3.1 Northern South America 26
1.3.2 Amazon Basin 26
1.3.3 Southern Brazil 27
1.3.4 Central Andes: Peru, Bolivia and North Chile 27
1.3.5 Central Plains of Argentina 29
1.3.6 Southern South America 30
1.4 Discussion 31
1.5 Conclusion 34
References 35
2 Orbital and Millennial-Scale Precipitation Changes in Brazil from Speleothem Records 43
2.1 Introduction 43
2.2 Climate Signals Recorded in Brazilian Speleothems 45
2.2.1 Climate Variability in South America Based on 0 18 O in Precipitation 45
2.2.2 Factors Affecting the Isotopic Composition of Dripwaters and Modern Speleothems 49
2.2.3 The Influence of Rainfall Amount on Mg/Ca and Sr/Ca Ratios in Speleothems 52
2.3 Paleoclimatic Changes from Speleothem Records 53
2.3.1 U/Th Chronology of Speleothems 53
2.3.2 Stable Isotope Records 56
2.3.3 Speleothem Growth Intervals 57
2.3.4 Mg/Ca and Sr/Ca Ratios 58
2.4 Discussion 61
2.4.1 Long-Term Paleoclimatic Changes 61
2.4.2 Millennial-Scale Abrupt Changes in Climate 64
2.4.3 Broader Significance of Precipitation Changes Based on Speleothem Records 68
2.5 Conclusions 68
References 69
3 Chronologies of the Last Glacial Maximum and its Termination in the Andes (1055S) Based on Surface Exposure Dating 75
3.1 Introduction 75
3.2 Geography and Current Climate in the Andes 76
3.3 Surface Exposure Dating 79
3.3.1 Principle 80
3.3.2 Scaling and Systematic Uncertainties 80
3.3.3 Scatter in Exposure Ages and Geomorphological Uncertainties 81
3.4 Chronologies of the LGM 82
3.4.1 Exposure Ages from the Tropical Andes of Peru and Bolivia 82
3.4.1.1 Comparison with Radiocarbon Chronologies 85
3.4.1.2 The Role of Temperature and Precipitation for Glaciation in the Southern Tropical Andes 86
3.4.2 Exposure Ages from the Subtropical Andes 88
3.4.3 Exposure Ages from the Patagonian Andes and Tierra del Fuego 90
3.5 Conclusions 93
References 95
4 Vegetation and Fire at the Last Glacial Maximum in Tropical South America 102
4.1 Introduction 102
4.2 Methods and Approach 103
4.3 Last Glacial Maximum Pollen-Based Vegetation Reconstructions 107
4.3.1 Andean Records 109
4.3.1.1 Bolivian Altiplano 109
4.3.1.2 Bolivian/Peruvian Cloud Forests 109
4.3.1.3 Colombian Montane Forests 110
4.3.2 Lowland Records 111
4.3.2.1 Amazon Rainforests 111
4.3.2.2 Savanna/Woodland/Thorn-Scrub 113
4.3.2.3 Atlantic Forests and Campos Grasslands of SE Brazil 113
4.4 Model Simulations of Last Glacial Maximum Vegetation 114
4.4.1 Colombia 114
4.4.2 Amazon Basin 115
4.5 Last Glacial Maximum Fires 118
4.6 Implications and Conclusions 119
4.6.1 Last Glacial Maximum Climate 119
4.6.2 Biogeography, Biodiversity, and Carbon Cycling 120
References 122
5 Re-evaluation of Climate Change in Lowland Central America During the Last Glacial Maximum Using New Sediment Cores from Lake Petn Itz, Guatemala 126
5.1 Introduction 126
5.1.1 The Lake Petán Itzá Scientific Drilling Project (PISDP) 127
5.2 Did Montane and Lowland Regions Experience the Same Degree of Last Glacial Maximum Cooling ? 131
5.2.1 Glaciological Evidence 131
5.2.2 Palynological Evidence 132
5.3 Was the LGM Characterized by Aridity? 133
5.4 Precession as a Long-Term Driver of Precipitation Change in Central America 134
5.5 Short-Term Drivers of Precipitation and Temperature 136
5.6 Conclusions 137
References 139
6 Glacial to Holocene Paleoceanographic and Continental Paleoclimate Reconstructions Based on ODP Site 1233/GeoB 3313 Off Southern Chile 142
6.1 Introduction 142
6.2 Regional Setting 144
6.3 Material and Methods 147
6.4 Results and Discussion 148
6.4.1 Glacial 149
6.4.1.1 Regional Aspects 149
6.4.1.2 Link to the High Latitudes 152
6.4.1.3 Link to the Tropics 152
6.4.2 Termination 1 154
6.4.2.1 Regional Aspects 154
6.4.2.2 Link to the High Latitudes 156
6.4.2.3 Link to the Tropics 158
6.4.3 Holocene 159
6.4.3.1 Regional Aspects 159
6.4.3.2 Link to the High Latitudes 162
6.4.3.3 Link to the Tropics 162
References 164
Part II The High Latitudes-Tropics and Tropics-Tropics Teleconnections over the Last Deglaciation and Last Glacial Maximum 170
7 Teleconnections into South America from the Tropics and Extratropics on Interannual and Intraseasonal Timescales 171
7.1 Introduction 171
7.2 Mechanisms of Tropics-Tropics and Tropics-High Latitudes Teleconnections 173
7.2.1 Walker and Hadley Circulation Cells 173
7.2.2 Rossby Wave Propagation 177
7.3 Teleconnections with South America on Interannual Time Scales 181
7.3.1 Southern Hemisphere Observed Interannual Variability 181
7.3.2 El Niño/Southern Oscillation Teleconnections with South America 183
7.3.2.1 Northern South America and the Tropics-Tropics Teleconnection 184
7.3.2.2 Southeastern South America and the Tropics-Extratropics Teleconnection 187
7.3.2.3 Central-East Brazil and the Influence of Regional Processes During the Summer Monsoon 190
7.4 Teleconnections with South America on Intraseasonal Time Scales 190
7.4.1 Southern Hemisphere Observed Intraseasonal Variability 191
7.4.2 Madden-Julian Oscillation (MJO) 193
7.5 Final Remarks 198
References 198
8 South American Climate Variability and Change: Remote and Regional Forcing Processes 204
8.1 Introduction 204
8.2 Decomposition of the South American Precipitation Climatology 206
8.3 Regional Forcing of South American Climate Variability 212
8.4 Remote Forcing of South American Climate Variability 216
8.4.1 Sea Surface Temperature Forcing 216
8.4.2 High Latitude Forcing 219
8.4.3 Africa and South America: An Intercontinental Teleconnection 219
8.5 Concluding Remarks 220
References 220
9 Sensitivity of South American Tropical Climate to Last Glacial Maximum Boundary Conditions: Focus on Teleconnections with Tropics and Extratropics 224
9.1 Introduction 224
9.2 Model Description and Simulated Thermo-Dynamical Structure of the Atmosphere 228
9.2.1 The Model and Experimental Set Up 228
9.2.2 Simulated Pre-industrial (PI) Climate 230
9.3 Response of Tropical South American Climate to Last Glacial Maximum Forcings 235
9.3.1 The Last Glacial Maximum 235
9.3.2 Sensitivity to Last Glacial Maximum Reduced Greenhouse Gases 240
9.3.3 Sensitivity to Last Glacial Maximum Land Ice 242
9.4 Summary and Conclusion 245
References 246
10 Similarities and Discrepancies Between Andean Ice Cores Over the Last Deglaciation: Climate Implications 250
10.1 Introduction and Motivations 250
10.2 Isotopic Composition of Andean Ice Cores: A Common LGM to Holocene Signal, Some Discrepancies Along the Deglaciation 254
10.2.1 An Important Caveat About Andean Ice Cores Dating 254
10.2.2 The Glacial-Interglacial Transition as Recorded in the Isotopic Composition of Andean Ice Cores 256
10.2.3 Deglaciation as Recorded in Andean Ice Cores: Deciphering the Greenland and Antarctic Aspects? 258
10.3 Discussion in Terms of Global Climate Mechanisms and Local Climate Influences 259
10.3.1 Influence of Insolation on LGM Precipitation 260
10.3.2 A Mechanism for Wet Southern Tropics and Cold Northern High Latitudes During LGM 260
10.3.3 Is a Climate Reversal Expected in the Isotopic Composition of Andean Ice Cores? 261
10.3.4 The Specificity of Sajama: Local Conditions and/or Pacific Influence? 261
10.4 Conclusions 262
References 263
Part III Characteristics of the Holocene Climate. Focus on Global Events: Are They Widespread, Comparable and Synchroneous in South America? 267
11 Mid-Holocene Climate of Tropical South America: A Model-Data Approach 268
11.1 Introduction 268
11.2 Methodology 271
11.3 Results 271
11.3.1 Present Tropical South America Climate as Simulated by IPSL Model (CTL) 271
11.3.2 ITCZ and ZCAS at the Mid-Holocene 274
11.3.3 Atmospheric Mean and Transient Circulation 278
11.4 Comparison with Paleoclimate Data 282
11.4.1 Precipitation 283
11.4.2 Temperature and Cold Outbreaks 285
11.5 Conclusions 286
References 287
12 Millennial-Scale Ecological Changes in Tropical South America Since the Last Glacial Maximum 291
12.1 Introduction 291
12.2 Rate-of-Change Analysis 292
12.3 Paleoecological Records 294
12.3.1 Andean vs Western Amazonian Changes 296
12.3.2 Drivers of Change 299
12.3.2.1 Temperature 300
12.3.2.2 Precipitation 301
12.3.2.3 Fire 302
12.3.2.4 Human Disturbance 302
12.4 Overview 303
References 305
13 The Nature and Origin of Decadal to Millennial Scale Climate Variability in the Southern Tropics of South America: The Holocene Record of Lago Umayo, Peru 309
13.1 Introduction 310
13.2 Precipitation in Tropical South America During the Late Quaternary and its Relationship to Tropical Atlantic Variability 313
13.3 Reconstruction of Holocene Precipitation in the Northern Altiplano, Lago Umayo, Peru 316
13.3.1 Regional Setting of Lago Umayo 316
13.3.2 Methods 320
13.3.3 The Oxygen Isotopic Model 321
13.3.4 Model Results and Validation 323
13.4 Discussion 324
13.5 Conclusions 326
References 327
14 Hydrological Variability in South America Below the Tropic of Capricorn (Pampas and Patagonia, Argentina) During the Last 13.0 Ka 331
14.1 Introduction 331
14.2 Modern Climate of Southern South America 332
14.3 Paleoclimate Archives 334
14.3.1 Subtropical Latitudes: Pampean Plains 336
14.3.2 Argentinean Patagonia and Extra-Andean Patagonia 341
14.3.3 Archeological and Historical Sources of Climate Variability in Central Argentina 346
14.4 Discussion 350
14.4.1 Climatic Driven Hydrological Changes in Southern South America (South of 30S). From the Late Glacial Times Until the Little Ice Age and the 20th Century 350
14.4.2 The 20th Century Climate Variability 353
14.5 Final remarks 353
References 354
15 Climate Change in Southern South America During the Last Two Millennia 360
15.1 Introduction 360
15.2 Climatology 364
15.2.1 Co-Variability of Wind and Precipitation 364
15.2.2 Seasonal Variations in Wind and Precipitation 365
15.2.3 Correlation Between Zonal Wind and Precipitation 366
15.2.4 El Niño-Southern Oscillation (ENSO) Variability 366
15.2.5 Southern Annular Mode (SAM)/Antarctic Oscillation (AAO) Variability 368
15.3 Lake Sediment Records 370
15.3.1 Lago Guanaco 371
15.3.2 Laguna Potrok Aike 374
15.3.3 Lago Cardiel 375
15.4 Pollen and Charcoal Records 376
15.5 Glacier Records 377
15.6 Tree-Ring Records 380
15.7 Marine Records 387
15.8 Summary and Directions for Future Research 390
References 395
16 The Little Ice Age in Southern South America: Proxy and Model Based Evidence 401
16.1 The Little Ice Age 401
16.2 The Climate of Southern South America 403
16.3 Proxy Data in Southern South America 404
16.3.1 Dendroclimatological Evidence 404
16.3.2 Lacustrine Investigations 406
16.3.3 Pollen Analysis 407
16.3.4 Ice Cores and Glacio-Geomorphological Evidence 408
16.4 Climate Modelling Studies for Southern South America 409
16.4.1 Reconstructing Local Climatic Changes by Means of Statistical Analysis 409
16.4.2 Changes of Precipitation and Southern Westerlies During the LIA 411
16.5 Conclusions and Outlook 414
References 415
Index 419