How to Build a Habitable Planet

Preface xv
Chapter 1. Introduction: Earth and Life as Natural Systems 1
Introduction 2
The Power and Limitations of Scientific Reductionism 4
Chaos 7
"Systems" 13
Characteristics of "Natural Systems" 15
Natural Systems Are Out of Equilibrium 15
Natural Systems Are Maintained by External Energy Sources 17
"Steady-State Disequilibrium" Is Maintained by Feedbacks and Cycles 17
Summary 24
Supplementary Readings 25
Chapter 2. The Setting: The Big Bang and Galaxy Formation 27
Introduction 28
The Big Bang 28
The Red Shift: Measuring Velocity 31
Measuring Distance 34
The Velocity-Distance Relationship: Dating the Beginning 41
Added Support for the Big Bang Hypothesis 43
An Expanding Universe and Dark Energy 47
Aftermath of the Big Bang 48
Summary 49
Supplementary Readings 49
Chapter 3. The Raw Material: Synthesis of Elements in Stars 51
Introduction 52
The Chemical Composition of the Sun 52
Hydrogen, Helium, Galaxies, Stars 54
Descriptive Atomic Physics 55
Element Production during the Big Bang 61
Element Formation in Stars 62
Element Synthesis by Neutron Capture 66
Evidence Supporting the Stellar Hypothesis 71
Summary 77
Supplementary Readings 81
Chapter 4. Preliminary Fabrication: Formation of Organic and Inorganic Molecules 83
Introduction 84
Molecules 88
States of Matter 90
Volatility 92
Density 94
The Two Great Classes of Molecules: Inorganic and Organic 95
Minerals 96
Organic Molecules 104
Environments of Molecular Construction 107
Summary 110
Chapter 5. The Heavy Construction: The Formation of Planets and Moons from a Solar Nebula 113
Introduction 114
Planetary Vital Statistics 117
Planetary Mass 117
Planetary Densities 119
Planetary Composition 120
Evidence from Meteorites 122
Scenario for Solar System Creation 128
Understanding the Chemical Compositions of the Terrestrial Planets 132
Summary 139
Supplementary Readings 139
Chapter 6. The Schedule: Quantifying the Timescale with Radionuclides 141
Introduction 142
Measuring Time with Radioactive Decay 145
The Isochron Technique of Radioactive Dating 150
Age of the Chondrites and Earth 154
Age of the Elements 157
Unlocking the Secrets of Ancient Short-lived Processes with
Extinct Radionuclides 164
²⁶Al and the Presence of Supernovas in the Vicinity of the Solar Nebula 165
Summary 168
Supplementary Reading 169
Chapter 7. Interior Modifications: Segregation into Core, Mantle, Crust, Ocean, and Atmosphere 171
Introduction 172
Earth Structure 173
Chemical Composition of Earth's Layers 180
Chemical Affinities of the Elements 183
Origin of Earth's Layers 188
Separation of Core from Mantle 189
Timing of Core Formation 191
Origin of the Crust 194
Origin of the Atmosphere and Ocean 204
Summary 206
Chapter 8. Contending with the Neighbors: Moons, Asteroids, Comets, and Impacts 209
Introduction 210
The Diversity of Objects in the Solar System 212
Origin of the Moon 218
Using Impacts to Date Planetary Surfaces 223
Lunar Interior Modifications 230
History of Impacts in the Solar System 236
Implications for the Earth 239
Future Impacts 245
Summary 246
Supplementary Readings 247
Chapter 9. Making It Comfortable: Running Water, Temperature Control, and Sun Protection 249
Introduction 250
The Planetary Volatile Budget 251
Evidence for Liquid Water before 4.0 Ga 253
Stable Isotope Fractionation 255
Controls on Volatiles at the Surface 257
Atmospheric Loss to Space 258
Cycling of Volatiles between the Surface and Earth's Interior 264
Surface Temperature 265
Earth's Long-Term Thermostat 271
A Lesson from Venus 276
Snowball Earth 278
Sun Protection 280
Summary 282
Supplementary Readings 282
Chapter 10. Establishing the Circulation: Plate Tectonics 285
Introduction 286
The Static Earth Viewpoint 287
Continental Drift Theory 289
New Data from the Ocean Floor 291
Evidence from Paleomagnetism 293
Global Distribution of Seismicity 298
The Theory of Plate Tectonics 301
The Plate Tectonic Revolution 306
Movements through Time 309
Summary 311
Supplementary Readings 312
Chapter 11. Internal Circulation: Mantle Convection and Its Relationship to the Surface 315
Introduction 316
Movement of Earth's Interior 317
Earth's Topography and Mantle Flow 319
Mantle Convection 322
Must the Mantle Convect? 325
Does Plate Geometry Correspond to Mantle Convection Cells? 328
Active Mantle Upwelling: Plume Heads and Tails 335
Formation of the Ocean Crust at Spreading Centers 342
Summary 347
Supplementary Readings 347
Chapter 12. Linking the Layers: Solid Earth, Liquid Ocean, and Gaseous Atmosphere 349
Introduction 350
The Global System of Ocean Ridges 351
Hydrothermal Circulation at Spreading Centers 354
Ocean Ridges and Habitability 362
The Puzzle of Seawater Composition 362
Element Transport to the Subduction Zone 366
Geochemical Processing at Convergent Margins 369
Cause of Melting and Volcanism at Convergent Margins 369
Element Transport to the Continental Crust 375
Final Consequences of Plate Recirculation 377
Summary 379
Supplementary Readings 381
Chapter 13. Colonizing the Surface: The Origin of Life as a Planetary Process 383
Introduction 384
Life and the Universe 385
The Unity of Life 390
Life Is Cellular 390
All Life Uses the Same Groups of Molecules 391
All Life Uses the Same Chemical Machinery 396
Earliest Life 398
When Did Life Begin? 401
Life's Origin 406
Steps in the Path to Life 408
Elemental and Simple Molecular Building Blocks 409
Making the Essential Biochemical Ingredients 410
Building Complex Molecules 412
A Cellular Container 415
The Missing Links 417
Some General Considerations on the Origin of Life 420
Summary 424
Supplementary Readings 424
Chapter 14. Dealing with the Competition: The Roles of Evolution and Extinction in Creating the Diversity of Life 427
Introduction 428
History of Life and Earth Revealed through the Rock Record 432
Relating Fossils to Present-Day Life: The Theory of Evolution 438
The DNA Revolution 441
The Extinction Half of Evolution 447
Summary 450
Supplementary Readings 451
Chapter 15. Energizing the Surface: Coevolution of Life and Planet to Create a Planetary Fuel Cell 453
Introduction 454
Life as an Electrical Current 455
A Reduced Early Earth 457
The First Three Energy Revolutions 463
The Planetary Fuel Cell 469
Summary 472
Chapter 16. Exterior Modifications: The Record of Oxidation of the Planetary Surface 475
Introduction 476
Earth and Oxygen 477
Carbon: The Record of Oxygen Production 480
Carbon: Evidence from the Rock Record 483
Iron and Sulfur: The Record of Oxygen Consumption 486
Iron: Evidence from the Rock Record 488
Sulfur: Evidence from the Rock Record 493
Evidence for High O2 in the Phanerozoic 497
Oxygen from 2.0 Ga to 0.6 Ga 498
Global Oxygen Mass Balance 502
Summary 506
Supplementary Readings 507
Chapter 17. Planetary Evolution: The Importance of Catastrophes and the Question of Directionality 509
Introduction 510
Planetary Evolution during the Phanerozoic 511
Causes of Extinction Events 516
The Cretaceous/Tertiary Extinction 517
The Permo-Triassic Extinction 521
Plate Tectonics and Evolution 526
Principles of Planetary Evolution? 527
Increased Relationship and Complexity 527
Change in Energy Utilization with Time 529
Speculations on the Possibility of Directionality to Evolution 531
Evolution of Habitability 534
Summary 536
Supplementary Readings 537
Chapter 18. Coping with the Weather: Causes and Consequences of Naturally Induced Climate Change 539
Introduction 540
Intermediate Term Climate Variations: Ice Ages 541
Orbital Cycles 544
Abrupt Climate Change 555
The Great Ocean Conveyor 560
Human Impacts 564
Summary 565
Supplementary Readings 565
Chapter 19. The Rise of Homo Sapiens: Access to Earth's Treasure Chest Permits a Planetary Takeover 567
Introduction 568
Dawn of the Human Era 569
The Human Energy Revolution 573
Earth's Treasure Chest 575
Classes of Resources 580
Resources with Short Recycling Times: Air and Water 580
Vast Resources with Recycling Potential: Metals 586
Finite Resources with No Recycling 589
Fossil Fuels 589
Soils 593
Biodiversity 593
Summary 594
Chapter 20. Mankind at the Helm: Human Civilization in a Planetary Context 597
Introduction 599
Human Impacts on the Earth 600
Climate 600
Ocean Acidification 611
Biodiversity 614
Future Prospects 620
Historical Perspectives on the Future 628
Possible Solutions 632
Solving Greenhouse Gas Accumulation 635
Energy from the Sun, Wind, and Atom 635
Carbon Capture and Sequestration 637
The Broader Problem 643
An Anthropozoic Era? 644
Summary 646
Supplementary Readings 646
Chapter 21. Are We Alone? The Question of Habitability in the Universe 649
Introduction 650
Comparative Planetology--Lessons from Venus and Mars 652
Planet Finding 654
New Results from Kepler 659
The Number of Other Inhabited Planets in the Galaxy: A Probabilistic Approach 661
Human Civilization in the Context of Planetary Evolution and Life in the Universe 665
Summary 667
Supplementary Readings 668
Glossary 669
Index 687