1. Potential Causes of Climate Change ENVS 110

2. orbital parameters

3. planetary temperatures

4. eccentricity: the influence of elliptical orbits http://astroprofspage.com/archives/1024 Note: for the Earth this difference is quite small – about 3%

5. the seasons http://avc.comm.nsdlib.org/cgi-bin/wiki.pl?Seasons_In_The_Sun

7. changes in the shape of the earth’s orbit affects how solar radiation is distributed throughout the year http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

8. axial tilt or obliquity determines how much sunlight reaches the northern and southern hemispheres during summer / winter influences the severity of the seasons

10. Milankovitch (over) simplified changes in orbital parameters change the way solar radiation is distributed across the earth it changes the absolute amount of solar radiation a little (due to Kepler’s second law) so why don’t the effects just average out?

11. equator http://www.planetaryvisions.com/release2007-1/satmap.jpg

12. Important Greenhouse Gasses Water vapor H 2 O0.1 ppm – 40,000 ppm Carbon Dioxide CO 2 370 ppm Methane CH 4 1.7 ppm Nitrous Oxide N 2 O0.3 ppm Ozone O 3 0.01 ppm (at surface) Freon – 11 CCl 3 F0.00026 ppm Freon – 12 CCCl 2 F 2 0.0054 ppm Data from Kump et al., 2004

13. The Greenhouse Effect Atmosphere transparent to visible light Atmosphere opaque to long wavelength radiation (infrared)

14. Change in CO 2 Concentrations

17. Long Term CO 2, CH 4 Variability Source: Vostok ice core record Petit et al., 2001

22. http://upload.wikimedia.org/wikipedia/commons/2/28/Sunspot_Numbers.png

23. total solar irradiance 1610 - 2000 The Reverend Robert Walker Skating on Duddingston Loch attributed to Henry Raeburn, 1790's Pieter Brueghel the Younger. Winter Landscape, 1621 little ice age London Bridge Frost Fair Luke Clenell, 1814

26. Mount Pinatubo erupts

27. feedback mechanisms initial signal quite small need amplifiers –ice albedo feedback –plant cover feedback –cloud feedback –radiation feedback –greenhouse gasses ?