1. CLIMATE CHANGE: BEYOND SCIENCE AND TECHNOLOGY Menahem E. Yaari Academy Presidents’ Forum Academia Sinica December 6-8, 2008 1

2. WHAT IS CLIMATE CHANGE (CC) ? CC Is Here CC Is Affecting / Will Affect Everyone (Humans and Other Species) CC’s Impact Is Very Long (Centuries) Action MUST be taken (“Doing Nothing” Is Also an Action) SOME UNDISPUTED FACTS CC Ξ LONG-TERM, SYSTEM-WIDE DEPARTURE FROM ESTABLISHED GLOBAL CLIMATE PATTERNS 2

3. PLAYERS = AGENTS WHO CAN ACT DELIBERATELY COUNTRIES REGIONS INDIVIDUALS THE INTERNATIONAL COMMUNITY WHO ARE THE CC-RELEVANT PLAYERS? 3

4. The INTERNATIONAL COMMUNITY is a special type of player, because it can set RULES for the other players What are its instruments? INTERNATIONAL ORGANIZATIONS AGREEMENTS AND TREATIES PUBLIC OPINION 4

5. A STRATEGY is a CONTINGENT PLAN for action Each player seeks to adopt a STRATEGY The STRATEGY tells the player what to do in each future period, AS A FUNCTION of the INFORMATION that will be available in that period INFORMATION ≡ Accumulated Climate Data Science Technology What the OTHERS have done so far 5

6. (KNOWING X does not tell us how to DEAL/COPE with X) Weighing benefits against adversities Weighing one person’s benefit against another person’s hardship Weighing the present against the (distant) future Weighing social phenomena (e.g. INEQUALITY) Getting the OTHERS to cooperate The strategy takes Science and Technology as INPUTS, so the SELECTION of a strategy necessarily takes us BEYOND Science and Technology. SOME ESSENTIAL ELEMENTS IN THE FORMATION OF A STRATEGY: 6

7. WEIGHING A MULTITUDE OF GAINS/LOSSES Utility Theory Cost-Benefit Analysis Absence of Observational Record The Psychology of Human Judgments 7

8. COMPARING DIFFERENT PEOPLES’ GAINS/LOSSES Ethics Utilitarian vs. Rawlsian vs. … Capabilities, Needs, Preferences 8

9. Unprecedented Length of the Time Horizon What is the “Correct” Rate of Discount? Private vs. Social (International?) Rate of Discount Future Generations are Just/Not Like Us The Problem with Zero Discounting “Natural” Rates of Discount DISCOUNTING THE FUTURE 9

10. Migration Congestion Accelerated Urbanization Reduced Diversity Inequality Political Change SOCIAL CONSEQUENCES 10

11. A Prisoners’ Dilemma Mechanism Design Creating Incentives International Implementation SETTING THE RULES 11