3. Milankovitch Theory of Climate Change The Earth changes its: a)orbit (eccentricity), from ellipse to circle at 100,000 year cycles, b)wobble (precession), from the north pole pointing toward or away from the sun in June at 23,000 year cycles, and c) tilt (obliquity), from 22° to 24.5° at 41,000 year cycles.

4. Climate Since the Most Recent Ice Age

5. Does a large, composite volcano affect climate on a global scale?

6. Effect of Mount Pinatubo Eruption Note: Volcanoes also release CO2, and warming occurs in the long term during tectonically active periods (eg. Triassic/Jurassic boundary) TEMPORARY COOLING

7. Ice core data Temperature, CO 2 and CH 4 are all in phase Are the gas concentrations an effect or a cause of warming or both?

8. The Jurassic A much warmer Earth with more CO 2

14. Source: IPCC

17. The Global Carbon Cycle - 1990s Units Gt C and Gt C y -1 The KP seeks to reduce net carbon emissions by about 0.3 Gt C below 1990 levels from industrial countries Atmosphere Fossil Deposits 6.3 63 91.7 60 90 3.2 Plants Soil Oceans 750 500 2000 39,000 About 16,000 1.6 …are leading to a build up of CO 2 in the atmosphere. Fossil emissions …and land clearing in the tropics...

21. 2xCO 2 ENVIRONMENT

22. Source: IPCC Enhanced photosynthesis

23. 19502006 Climate Modelling

28. Temporary, regional cooling effect

29. Source: IPCC

31. 1.Reduced Biodiversity Rapid change may exceed capacity of plants and animals to adapt to changing climate and new interspecies dynamics 2.Sea level rise and coastal flooding Thermal expansion + melting ice 3.Expansion of tropical disease range

32. 4.Soil Moisture Decreases and Desertification Evapotranspiration increases may exceed increases in precipitation 5.Increased frequency of heat illness 6.Increased frequency of severe events? More energy for tropical cyclones (supports this hypothesis), but reduced latitudinal temperature gradients could reduce middle-latitude storm intensity

33. 7. Engineering problem of thermokarst (transportation and housing) 8.Affect on outdoor winter recreation and winter tourism

34. Alberta’s Fragile Fresh Water Supply Partially supported by glacial meltwater Glaciers are retreating Future ET >> P?

38. 1.Increasing ecosystem productivity Higher photosynthesis rates due to carbon fertilization 2.Increased food production Higher photosynthesis rates, wider range where soils adequate, longer growing season (depends on soil moisture/depth/nutrients)

39. 3.Increased water-use efficiency Plants can reduce stomatal aperture, yet maintain sufficient internal CO 2 May mitigate desertification and soil moisture deficit somewhat 4.Increased nutrient-use efficiency? Is less Rubisco required at higher temperatures? (Contains N) 5.High latitude warming Both a negative effect (loss of key Arctic species, ways of life) and positive effect (crop growth &  NPP, soil permitting)

40. Free Air Carbon Dioxide Enrichment (FACE)

41. FACE Results: NPP increases (eg. 40% in cotton; 25% for Sweetgum for 550 ppm vs. 370 ppm) Carbon sink increase limited for forests: Increase in wood production is short-lived; C goes mainly to fine roots and leaves; affected by soil fertility No effect on LAI Stomatal conductance decreases (increased water- use efficiency) Lower leaf nitrogen concentration: Do they need less? Have less? Due to C:N ratio?

43. Source: IPCC

44. Meanwhile, we are detecting stratospheric cooling ! Why ? Ozone depletion Tropospheric [CO 2 ] increases

46. Further Reading: Fundamentals of Physical Geography Online 7h. The Greenhouse Effect http://www.physicalgeography.net/fundamentals/7h.html Climate Change 2001: The Scientific Basis International Panel on Climate Change http://www.grida.no/climate/ipcc_tar/wg1/index.htm