Climate and Climate Change

1. Climate and Climate Change

2. Essential Points • Climate and weather prediction are completely different • Detecting climate change is very complex • The main greenhouse gas on Earth is water vapor • A little greenhouse effect is a good thing • Many things have affected earth’s past climate • Gradual brightening of the sun will eventually make the earth too hot for life

3. Climate Versus Weather

4. Climate is what you expect and weather is what you get

5. Green Bay 1977-2002

6. Green Bay 1887-2002

7. Green Bay 1887-2002

8. Green Bay 1887-2002

9. Long-Term Trends

10. Long-Term Trends

11. Long-Term Trends

12. Long-Term Trends

13. Long-Term Trends

14. Some Conclusions • This is not as easy as the media make it seem • The fact that it’s not easy doesn’t excuse us from dealing with it • The fact that something can’t be proven conclusively doesn’t protect you if you make the wrong decision • Don’t confuse reasoning with reality. Just because you can justify believing something doesn’t make it true.

15. Greenhouse Effect

16. Negative Greenhouse Effect

17. Positive and Negative Greenhouse Effects Positive Greenhouse Effect • Light enters • IR trapped: Warming Negative Greenhouse Effect • Light Blocked • IR can leave: Cooling • Titan

18. Greenhouse Gases • Water Vapor • Carbon Dioxide • Methane • Nitrous and Nitric Oxides • Ozone • Transparent to visible light but absorb infrared

19. What Color is Water?

20. What Color is Ice?

21. Infrared Absorption

22. Carbon Dioxide • Has doubled to 380 ppm since start of Industrial Revolution • Coupled to Temperature Rise? • More Cloud Cover? • Taken up by biomass? • Taken up by oceans?

23. Paleoclimatology • The present is the key to the past – but • The past is also the key to the present • Study of ancient climates • Have to rely on proxy measurements • How to convert qualitative data to numbers?

24. Ancient Paleoclimatology • Oxygen 18 • Fossils • Evaporites • Glacial Indicators • Air bubbles in amber

25. Earth’s Climatic History • Faint Early Sun • Anoxic Early Atmosphere • Advent of Life – UV Protection? • 2.3 b.y. Glaciation • 2 b.y. Oxygen Threshold • End of Iron Formations • First Red Sandstones • 900-600 m.y. Snowball Earth

26. Earth’s Climatic History • 600-500 m.y. Cambrian “Explosion” • 450 m.y. Ordovician Ice Age • 350 m.y. Advent of Forests • 350-250 m.y. Permian Ice Age • 100 m.y. Cretaceous Warm Period • 50 m.y. Eocene Warm Period • Pleistocene Ice Age

27. Recent Paleoclimatology • Historic Records • Tree Rings • Pollen Studies • Oxygen 18 • Ice Cores

28. Holocene Climate • 11,000 Younger Dryas Cooling • 9,000-6,000 Mid-Holocene Warm Period (“Climatic Optimum”) • 900-1300 AD – Medieval Warm Period • 1300-1450 Little Ice Age I • 1450-1550 Partial Recovery • 1550-1800 Little Ice Age II

29. Possible Effects of Global Warming • More Heat Extremes • Drought • Rise in Sea Level • Temporary Severe Cold Spell? • Rapid Migration of Ecological Zones • More Biomass but Lower Nutritional Value

30. Not a Bad Thing? • Reduced Energy Demands • Longer Growing Seasons • More Biomass • More Habitable Land

31. What We Know and Don’t Know • Certain: Carbon Dioxide Increase • Nearly Certain: Climate is Warming • Debatable (Legitimately) • How much is of human origin? • Permanent or temporary warming? • Uncertain: • Can we do anything? • Will benefits exceed costs? • Risks of premature policy decisions?

32. The Spectrum of Skepticism

33. Ozone Stratosphere – Good • Absorbs solar ultraviolet Troposphere – Bad • Toxic • Contributes to air pollution

34. Ozone Depletion • Cl stripped off synthetic molecules by solar ultraviolet • Cl reacts with ozone, acts as catalyst • Cl – CF3 (Freon) 360 • Cl – CCl3 (Carbon tetrachloride) 294 • Cl – H (Hydrochloric Acid) 431

35. Smog

36. Particulate Matter

37. Long-Term Climatic Trends • Brightening of the Sun • Capturing of CO2 by carbonate rocks? • Extinction of plants • Moist greenhouse effect • Runaway CO2 Greenhouse Effect • Venus conditions

38. The Ultimate Long-Term Forecast • Slow warming trend for the next billion years • Increasing humidity • Boiling and evaporation of the oceans, accompanied by extinction of life

39. The Goldilocks Problem • Venus is too hot • Mars is too cold • Earth is J-u-st Right

40. Planetary Habitable Zones • Primarily in the Liquid Water Zone • Ice is OK but planet can’t be too warm • Water Vapor in upper atmosphere broken down by solar UV and charged particles (photodissociation) • Hydrogen escapes to space • Can lose oceans in 100 m.y.

41. Planetary Habitable Zones

42. Future of Life • Plants need > 10 ppm CO2 • Animals and plants die around 50 C • Micro-organisms can tolerate 130 C + • But biology seems to like heat and we have a billion years to experiment • Pressurized cells? • Anti-boiling fluids? • Problem is breakdown of organic molecules • 200 C (380 F) max?

43. The Oreo Model of Life History Micro-organism Earth (0-3 billion years) Multicellular Earth (3-5 billion years) Micro-organism Earth (5-6 billion years) “The white creamy middle”

44. Essential Points • Climate and weather prediction are completely different • Detecting climate change is very complex • The main greenhouse gas on Earth is water vapor • A little greenhouse effect is a good thing • Many things have affected earth’s past climate • Gradual brightening of the sun will eventually make the earth too hot for life