1. Global Warming Inez Fung University of California, Berkeley April 2007

2. Climate Change: Recent News Feb 7 2007: United Nations Env Programme - Intergovt Panel on Climate Change - observed warming since the 20 th C is very likely due to anthropogenic greenhouse gases April 2 2007: US Supreme Court: anthropogenic CO 2 is a pollutant April 7 2007: UNEP IPCC WG 2 - warming has had discernible influence on physical and biological systems

3. Changing Composition of the Atmosphere Analysis of ancient air bubbles trapped in ice Direct measurements of atm composition in the past centuries Increases since 1800 due to human activities

5. At equilibrium: High CO 2 --> warm; Low CO 2 --> cold J. Hansen

6. The Last 500,000 years and the last 200 years J. Hansen

7. Global mean temperatures are rising faster with time 100 0.074  0.018 50 0.128  0.026 Warmest 12 years: 1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000 Period Rate Years  /decade IPCC AR4

8. The most important spatial pattern (top) of the monthly Palmer Drought Severity Index (PDSI) for 1900 to 2002. The time series (below) accounts for most of the trend in PDSI. Drought is increasing most places Mainly decrease in rain over land in tropics and subtropics, but enhanced by increased atmospheric demand with warming IPCC AR4

9. Climate Feedbacks Warming Evaporation from ocean, Increase water vapor in atm Enhance greenhouse effect Decrease snow cover; Decrease reflectivity of surface Increase absorption of solar energy Increase cloud cover; Decrease absorption of solar energy

10. Attribution are observed changes consistent with  expected responses to forcings  inconsistent with alternative explanations Observations Climate model: All forcing Climate model: Solar+volcanic only IPCC AR4

11. 9oF9oF 7oF7oF 3oF3oF Projections of Climate Change IPCC AR4

12. greatest over land & at most high N latitudes and least over the South. Ocean & parts of the N Atlantic Ocean Projections of Climate Change IPCC AR4

13. Jay Zwally Warming is faster than model projections: Recent rapid melting glaciers on Greenland

14. Stern Review 2006

16. Strong action is needed urgently Stern Review 2006