Ocean in the Earth System

Complexity is an intrinsic property of natural systems. In the oceanic system, it is linked to many interactions with the atmosphere, geosphere and biosphere with which it exchanges energy and matter. Complexity of the ocean system has, at different spatial and temporal scales, hydrodynamic mechanisms of these exchanges and dynamics of elements and compounds, they are involved in biogeochemical cycles or used as tracers. By its pedagogical approach, it defines the terms, methods, techniques and analytical tools used. Then, it analyzes the consequences of climate change, future projections, human impact and the concept introduced with planktonic pelagic ecosystem component.

Auteur

André Monaco is Emeritus Director of Research for the French national research center (CNRS). His research interests concern marine sedimentology and geochemistry. He was responsible for part of the organizing committee for several French and European programs and has been guest editor for four special issues in international journals.

Patrick Prouzet is Director of Research focusing on the ecosystemic approach at Ifremer in France. He specializes in the biology and dynamics of anadromous fish such as Atlantic salmon and eels. He is the author or co-author of several works on these species or on estuary fishing.

Contenu

FOREWORD xi

CHAPTER 1. THE OCEAN IN THE EARTH SYSTEM: EVOLUTION AND REGULATION 1
Philippe BERTRAND

1.1. The Earth system and its components 1

1.1.1. A system is a set of objects whose limit is arbitrary, but pertinent 1

1.1.2. One system is necessarily built into another 3

1.1.3. The Earth is a closed system 4

1.1.4. The major components of the Earth system 7

1.1.5. What is the biosphere? 8

1.2. The ocean, from its origins 9

1.2.1. Was there an ocean 4.4 billion years ago? 9

1.2.2. The origin of water on Earth (4.5 4 billion years ago) 9

1.2.3. The ocean and the end of the Venus phase of the Earth's history (between 4.5 and 4 billion years ago) 10

1.2.4. Why are there oceans on Earth and a Venus inferno on Venus? 13

1.2.5. The ocean, cradle of the first living creatures (between 4.4 and 3.5 billion years ago) 16

1.3. The ocean, oxygen and the evolution of life forms 18

1.3.1. The essential characteristics had been selected in the ocean before the Cambrian period, over 540 million years ago 18

1.3.2. How did oxygen accumulate? 21

1.3.3. The first important accumulation of oxygen (around 2.5 billion years ago) 25

1.3.4. A moderate increase in oxygenation (between 2.5 and 0.5 billion years ago) 26

1.3.5. The second important accumulation of oxygen (between 500 and 350 million years ago) 27

1.4. The regulation of the greenhouse effect by the ocean 29

1.4.1. There is no life without a minimum greenhouse effect 29

1.4.2. The regulation of the greenhouse effect by the ocean 30

1.5. Oceanic photosynthesis regulates itself on a short timescale 36

1.5.1. When the ocean is deficient in nitrate 38

1.5.2. When the ocean has an excess of nitrate 40

1.5.3. The regulation of the N/P ratio 41

1.6. Conclusion 43

1.6.1. The ocean in the Earth system 43

1.6.2. The anthropogenic disturbance of the Earth system 45

1.6.3. And life among all that? 47

1.7. Acknowledgments 49

1.8. Bibliography 49

CHAPTER 2. THE OCEAN AND THE CLIMATE SYSTEM 55
Pascale DELECLUSE

2.1. Introduction 55

2.2. Climate change 55

2.2.1. The report on the findings 56

2.2.2. Interpretation of the observed changes 58

2.2.3. The Earth's radiative equilibrium and greenhouse gases 59

2.2.4. The role of greenhouse gases GHG60

2.2.5. Scenarios and projections 63

2.3. Physics and dynamics 67

2.3.1. Rotation, Coriolis, geostropy 69

2.3.2. An ocean moved by the wind 71

2.3.3. Ekman, spiral, transport, pumping, upwelling and downwelling 71

2.3.4. Interior ocean and western boundary currents 77

2.3.5. An ocean moved by thermohaline fluxes 80

2.3.6. Stratification, mixed layer, thermocline 82

2.3.7. Formation of water masses, convection and subduction 83

2.3.8. Schematization of global circulation: the great conveyor belt 85

2.4. Some key elements for understanding the ocean's role in the climate 88

2.4.1. Typical times 88

2.4.2. Oceanatmosphere in the tropics 90

2.4.3. Other types of variability 95

2.4.4. Climatic surprises 97

2.5. Some questions for the future 100

2.6. Bibliography 102

CHAPTER 3. OCEANATMOSPHERE INTERACTIONS 105
Laurence EYMARD and Gilles REVERDIN

3.1. Introduction: what are oceanatmosphere interactions? 105

3.2. Interface processes and their role in the coupled system 106

3.2.1. Radiative fluxes 107

3.2.2. Turbulent fluxes 109

3.2.3. Water exchanges between the ocean and atmosphere 115

3.2.4. Other exchanges of matter 118

3.2.5. Flux measurement 125

3.3. Examples of energy exchanges 129

3.3.1. Tropical cyclones 129

3.3.2. Surface temperature fronts 132 3.3.3. The interacti...