About This Report iii
Summary vii
Figures and Tables xv

CHAPTER 1 Introduction 1
Scope of the Study 1
Methods 2
Organization of the Report 2

CHAPTER 2 What Are Catastrophic Risk and Existential Risk? 5
Accounts of Existential Risks 5
Global Catastrophic Risk 7
Related Risk Concepts 9
Perceptions of Global Catastrophic Risks and Their Importance 11
A Way Ahead 16

CHAPTER 3 Risk Frameworks and Approach 17
The Global Catastrophic Risk Management Act Risk Assessment Framework 17
Global Catastrophic Risks and Uncertainty 20
Why We Do Not Focus on Probabilities 21
Risk Management Frameworks 22

CHAPTER 4 Supervolcanoes: Summary of Risk 27
What Is Known About the Causes of Risk from Supervolcanoes? 28
What Are the Risks from Supervolcanoes? 35
What Has Been and Could Be Done to Manage Risk from Supervolcanoes? 41
Summary 43

CHAPTER 5 Asteroid or Comet Impact: Summary of Risk 45
What Is Known About the Causes of Risk from Asteroid and Comet Impacts? 46
What Are the Risks from Asteroid and Comet Impacts? 47
What Has Been and Could Be Done to Manage Risk from Asteroid and Comet Impacts? 55
Summary 60

CHAPTER 6 Severe Pandemics: Summary of Risk 63
What Is the Risk from Pandemics? 64
What Is Known About the Causes of Risk from Pandemics? 66
What Has Been and Could Be Done to Manage Risk from Pandemics? 77
Summary 78

CHAPTER 7 Rapid and Severe Climate Change: Summary of Risk 81
What Is Known About the Causes of Risk from Rapid and Severe Climate Change? 82
What Is the Risk from Rapid and Severe Climate Change? 89
What Has Been and Could Be Done to Manage Risk from Extreme Climate Change? 98
Summary 99

CHAPTER 8 Nuclear War: Summary of Risk 101
What Is Known About the Causes of Risk from Nuclear War? 102
What Is the Risk from Nuclear War? 105
What Has and Could Be Done to Manage Risk from Nuclear War? 111
Summary 112

CHAPTER 9 Artificial Intelligence : Summary of Risk 113
What Do We Mean by “Artificial Intelligence”? 114
How Can Artificial Intelligence Amplify Catastrophic Risks? 115
How Quickly Will Artificial Intelligence Improve? 120
What Is the Risk from Artificial Intelligence? 120
What Has Been and Could Be Done to Manage Risk from Artificial Intelligence? 126
Summary 128

CHAPTER 10 From Assessment to Management of Global Catastrophic or Extinction-Level Risk 129
Trends in Global Catastrophic and Existential Risk 131
Common Factors Affecting All Six Sources of Global Catastrophic Risk 132
The Geographic Extent of Consequences and Quality of Evidence About Risks Offer Guidance for
Appropriate Risk Management Strategies 135
Risk Management and Global Catastrophic and Existential Risks 138
Recommendations 142

APPENDIXES
A. Literature Search Strategy 145
B. Glossary 157
C. Works Cited, by Chapter 159

Abbreviations 189

References 191