1. Global Climate Change

2. 150 Authors 1,000 Contributing Authors 5 Years Work 130 Countries 1,000 Expert Reviewers The IPCC WGI Report

3. Key Messages The climate has warmed, will continue to warm, and humans are the cause Mitigation will not substantially affect the climate over the next few decades But, choices made now will have a big impact on the late 21 st century climate

4. Vostok Ice Core Looking Back in Time

5. Looking Back 650,000 Years N20N20 CH 4 CO 2 T Thousands years before 1950

6. Looking Back 130,000 Years

7. Looking Back 1,300 Years Year Little Ice Age Medieval Warm Period Temperature Change (°C)

8. Looking Back 150 Years Year ~1°C Temperature Change (°C)

9. SurfaceAbove Where is This Happening? Global temperature trends from 1979 to 2005

10. An “Explosion” of New Data Oceans are warming Glaciers are retreating Ice sheets are melting Sea level is rising Sea-ice is melting

11. Oceans are Warming Year Heat Content Change

12. Photos: US Geological Service, via National Snow and Ice Data Centre 1909 Toboggan Glacier, Alaska 2000 Glaciers are Retreating Year Length Change (m)

13. Ice Sheets are Melting Elevation Change (cm/year)

14. Reconstructed sea level fields Tide gauges Satellites Sea Level is Rising ~20 cm Year Sea Level Change (mm)

15. Sea-ice is Melting Year Millions of square km 2007 2008

16. Why is This Happening? Climate models are used to understand and predict climate change Based on sound physical principles, and subject to extensive validation

18. Observations Climate Models

19. Observations Climate Models

20. What About the Next 20 Years? 0.5°C

21. What About the Next 90 Years? 1-4°C

22. Expect Large Warming Over Land Surface temperature change (ºC) out to 2050

23. Expect Regional Precipitation Change Precipitation change (mm/day) out to 2090

24. Expect Sea Level Rise ~ 0.5 m Local sea level change (m) out to 2090

25. droughts hurricanes floods What about extreme events?

26. Trend towards more extreme temperatures Very warm nights Very warm days Trends (days per decade) in the frequency of extreme temperatures

27. Trend towards more very wet days Trend 1951 – 2003 contribution from very wet days

28. “Likely trend since 1970 towards more intense tropical storms in some regions” Wind energy index for named tropical storms

29. Expect heavier precipitation Expect more heat waves Expect more drought Expect more frost days

30. Key Messages Once Again The climate has warmed, will continue to warm, and humans are the cause Mitigation will not substantially affect the climate over the next few decades But, choices made now will have a big impact on the late 21 st century climate

31. Global Climate Change