Stabilization of Atmospheric Greenhouse Gases: Physical,

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Biological and Socio-economic Implications

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4408

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Intergovernmental Panel on Climate Change

1999

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Contents

Preface v

Summary . 3

1. Introduction 7

1.1 Aims . 7

1.2 Key Points . 8

1.2.1 Some Fundamentals Regarding Greenhouse Gases and Tropospheric Aerosols (see SAR WGI

for more details) 8

1.2.2 Stabilization of CO2 Concentrations (see SAR WGI for more details) . 8

1.2.3 Taking the Climatic Effects of Other Greenhouse Gases and Aerosols into Account: the

Concept of Equivalent CO2 8

1.2.4 The Global Temperature and Sea Level Implications of Stabilizing Greenhouse Gases . 8

1.2.5 Impacts . 9

1.2.6 Mitigation Costs of Stabilizing CO2 Concentrations . 9

1.2.7 Integrating Information on Impacts and Mitigation Costs . 10

1.3 A “Road map” to this Report . 10

1.3.1 Report Strategy 10

1.3.2 Decision-making Frameworks . 11

2. Geophysical Implications Associated with Greenhouse Gas Stabilization 13

2.1 General Principles of Stabilization: Stabilization of Carbon Dioxide and Other Gases 13

2.2 Description of Concentration Profiles, Other Trace Gas Scenarios and Computation of

Equivalent CO2 . 13

2.2.1 Emission Consequences of Stabilization 13

2.2.1.1 Concentration Profiles Leading to Stabilization . 13

2.2.1.2 Emissions Implications of Stabilization of CO2 Concentrations . 13

2.2.1.3 Critical Carbon Cycle Uncertainties 16

2.2.2 Stabilization of CH4, N2O and Other Gases . 16

2.2.3 Reference Stabilization Scenarios . 18

2.2.4 Stabilizing Equivalent CO2 Concentration 19

2.2.5 Equivalent CO2 Sensitivities . 21

2.3 Temperature and Sea Level Consequences of Stabilizing CO2 Concentrations 23

2.3.1 Temperature and Sea Level Analyses: Methodology . 23

2.3.2 Implications of Stabilization of Greenhouse Gases for Temperature and Sea Level 24

3. Impacts and Mitigation Costs Associated with Stabilizing Greenhouse Gases 29

3.1 Impacts Associated with Different Emissions Trajectories . 29

3.1.1 The Importance of Impacts in Decision Making on Stabilization . 29

3.1.2 Assessment of Potential Biophysical Impacts in SAR WGII . 29

3.1.3 Economic Assessment of Impacts . 30

3.1.4 Uncertainties in Projecting Impacts of Different Trajectories 31

3.2 Mitigation Costs of Stabilizing CO2 Concentrations 32

3.2.1 Economic Considerations Associated with Stabilizing CO2 Concentrations . 33

3.2.1.1 The Amount of Carbon to be Removed . 33

3.2.1.2 The Stabilization Target . 33

3.2.1.3 Cost Differential Between Fossil Fuels and Carbon-free Alternatives . 33

3.2.1.4 The Emissions Pathway . 34

3.2.2 Modelling the Costs of Stabilizing CO2 Concentrations 36

3.2.2.1 Studies Available at the Time of the SAR WGIII 36

3.2.2.2 Limitations of Existing Studies . 37

3.2.3 Other Key Considerations . 37

3.3 Integrating Information on Impacts and Mitigation Costs 37

3.3.1 Introduction . 37

3.3.2 The Need for Consistency and a Broad Perspective . 37

3.3.3 Portfolio Analysis . 38

3.3.4 Sequential Decision Making . 39

References . 41

Appendices . 43

1 Temperature and Sea Level Consequences of Stablilization of CO2 Concentrations from 1990 to

2300 43

2 Glossary of Terms 45

3 Acronyms and Abbreviations 49

4 Units 50

5 Lead Authors’ Affiliations 51

6 List of IPCC Outputs 52