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Global Warming

Global Warming

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Global Warming

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  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 20thC is very likely due to anthropogenic greenhouse gases • April 2 2007: US Supreme Court: anthropogenic CO2 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

  4. CO2 CH4 T Now 400,000 yr

  5. At equilibrium:High CO2 --> warm; Low CO2 --> cold J. Hansen

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

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

  8. Drought is increasing most places Mainly decrease in rain over land in tropics and subtropics, but enhanced by increased atmospheric demand with warming 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. IPCC AR4

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

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

  11. 9oF 7oF 3oF Projections of Climate Change IPCC AR4

  12. Projections of Climate Change 2020-2029 2090-2099 greatest over land & at most high N latitudes and least over the South. Ocean & parts of the N Atlantic Ocean IPCC AR4

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

  14. Stern Review 2006

  15. 2000 2020 Stern Review 2006

  16. Strong action is needed urgently Stern Review 2006