1. Feedbacks and Abrupt Climate Change

2. Review of last lecture Global climate models: Earth system models (5 components) Global climate models can reproduce the observed warming in the 20th century. The warming is largely caused by human activities. Projected change: mean temperature (largest warming over Arctic, larger over land), mean precipitation, sea level, extreme temperature, extreme precipitation, fresh water, ecosystems Future climate scenarios show that reducing greenhouse gas emissions can substantially mitigate warming in the latter half of this century.

3. Observed Change in Global Temperature: Significant warming

4. Global map of temperature change: Largest warming in Arctic (“Arctic amplification”) Larger warming over land than ocean

5. Projected Change in Global Temperature: Significant warming The spread comes from uncertainties in climate feedbacks

6. Main climate feedbacks for global warming Ice albedo Temperature (Lapse rate) Water vapor Cloud Aerosol Carbon cycle

7. Ice albedo feedback – Arctic amplification

8. Water vapor feedback

9. Video: The climate wild card https://www.youtube.com/watch?v=Py1dEFKuJJU

10. Cloud feedback Stronger warming effect Stronger cooling effect

11. Global carbon cycle

12. Carbon cycle feedback Example 1: Permafrost thaw

13. Carbon cycle feedback Example 2: Biosphere

14. Carbon cycle feedback sources

15. Video: A global warning? https://www.youtube.com/watch?v=_plr6b Ho5j8https://www.youtube.com/watch?v=_plr6b Ho5j8

16. Projected Change in Global Temperature: Didn’t consider the abrupt change

17. Abrupt climate change and tipping point – Lesson from Earth’s climate history

18. Bifurcation and tipping point

19. Examples of tipping points

20. Summary Large spread in projected temperature change comes from uncertainties in climate feedbacks Main climate feedbacks for global warming: ice-albedo, temperature, water vapor, cloud, aerosol, carbon cycle Abrupt climate change and tipping points

21. Works cited http://www.jpl.nasa.gov/images/earth/20100325/atlantic20100325- full.jpghttp://www.jpl.nasa.gov/images/earth/20100325/atlantic20100325- full.jpg http://www.nasa.gov/centers/goddard/news/topstory/2004/0315humid ity.htmlhttp://www.nasa.gov/centers/goddard/news/topstory/2004/0315humid ity.html http://sitemaker.umich.edu/section2_group1/arctic_issues__permafros thttp://sitemaker.umich.edu/section2_group1/arctic_issues__permafros t http://www.all-creatures.org/hope/gw/02_Arctic-Antarctic.htm http://www.fedre.org/en/content/global-permafrost-zones-high- resolution-images-google-earthhttp://www.fedre.org/en/content/global-permafrost-zones-high- resolution-images-google-earth http://www.onlyzerocarbon.org/arctic_feedback.html https://www.marietta.edu/~biol/biomes/tropdry.htm http://www.nwf.org/Wildlife/Threats-to-Wildlife/Global- Warming/Global-Warming-is-Causing-Extreme- Weather/Wildfires.aspxhttp://www.nwf.org/Wildlife/Threats-to-Wildlife/Global- Warming/Global-Warming-is-Causing-Extreme- Weather/Wildfires.aspx http://www.opb.org/news/blog/ecotrope/qa-how-to-reduce-wildfire- severity-even-in-a-warmer-climate/http://www.opb.org/news/blog/ecotrope/qa-how-to-reduce-wildfire- severity-even-in-a-warmer-climate/