1. 1.Greenhouse Effect 2.The CO 2 Cycle, Long-Term Climate Change 3.Ice Ages and Short-Term Climate Change 4.Human-Induced Climate Change

2. Global Climate History Geologic evidence clearly indicates relative long-term climate stability that has allowed liquid H 2 O to exist for most of geologic history.

3. The Earth’s Climate System - very complex!!

4. Earth’s Atmosphere 77% N 2, 21% O 2, 1% Ar, + trace gases (CO 2, CH 4, H 2 O) Absorbs incoming solar radiation and warms the planet. Important component of global climate.

5. Without atmosphere, average Earth temperatures would be a cool –17°C!!

6. The Greenhouse Effect

7. Greenhouse effect gives +32°C warming and allows for liquid H 2 O to exist on the planet

8. The Greenhouse Effect CO 2, CH 4, N 2 O, CFC’s, O 3, H 2 O vapor

9. 1.Greenhouse Effect 2.The CO 2 Cycle, Long-Term Climate Change 3.Ice Ages and Short-Term Climate Change 4.Human-Induced Climate Change

10. What regulates the amount of CO 2 ?? The concentration of greenhouse gases, particularly CO 2, is important global climate regulation

11. The CO 2 Cycle Sources: volcanism, metamorphism, respiration, fossil fuel burning, deforestation Sinks: photosynthesis, rock weathering, carbonate depsoition, ocean adsorption

12. Increased volcanism inputs huge quantities of CO 2 into the atmosphere = T° increases The CO 2 Cycle as Earth’s Thermostat T° increase causes increased chemical weathering and marine carbonate deposition which lowers atmospheric CO 2

13. Feedback is not instantaneous! Perturbations in CO 2 cycle take on the order of 500,000 years to restore. The CO 2 Cycle as Earth’s Thermostat

14. Long-Term Climate Change Tectonics plays an important role in regulating atmospheric CO 2 and therefore climate

15. Mechanisms for Long-Term Climate Change 1.Geographic Arrangement of Continents 2.Amount of Volcanic Activity 3.Uplift of Large Mountain Ranges Mid Cretaceous Warm Period

16. Increased Mid-Cretaceous Volcanic Activity

17. Mechanisms for Long-Term Climate Change 1.Geographic Arrangement of Continents 2.Amount of Volcanic Activity 3.Uplift of Large Mountain Ranges (Himalayas, Tibetan Plateau) Cenozoic cooling

18. Uplift of Himalaya Mtns and Tibetan Plateau Indian Plate (continental) Eurasian Plate (continental) Exposure of large volume of crust increases chemical weathering and lowers atmospheric CO 2

19. 1.Greenhouse Effect 2.The CO 2 Cycle, Long-Term Climate Change 3.Ice Ages and Short-Term Climate Change 4.Human-Induced Climate Change

20. Major Ice Ages in Earth History 2,000,000 million years to present The classic “Ice Age”

21. COLD WARM Short-Term Climate Change Climate change over short time scales (<1,000,000 years) Related to complex, poorly understand interactions between atmosphere, hydrosphere, and lithosphere

22. Last Ice Age was ~6  C colder than present temperatures Last glacial

23. The Last Ice Age Northern NJ was covered by ~1 km thick ice sheet 30% of the land surface was covered by ice (only 10% is covered today)

24. COLD WARM Possible Causes 1.Orbital Parameters of the Earth 2.Changes in Atmospheric Composition 3.Changes in Ocean Circulation 4.Sunspot Activity 5.Changes in Reflectivity (albedo) Short-Term Climate Change Climate change over short time scales (<1,000,000 years) Related to complex, poorly understand interactions between atmosphere, hydrosphere, and lithosphere

25. Orbital Parameters Cause variations in solar radiation with times scales <100,000 years

26. Radiation variation from summed orbital parameters matches the timing of warm and cold periods on Earth

27. 1.Greenhouse Effect 2.The CO 2 Cycle, Long-Term Climate Change 3.Ice Ages and Short-Term Climate Change 4.Human-Induced Climate Change

28. Atmospheric CO 2 Data Ice Core Data Direct Measurements, Hawaii

29. Recent Global Warming

30. GCM Models of Continued Global Warming between 1995 and 2050

31. GCM Models of Continued Global Warming

32. Is plate tectonics required for life? not likely for the origin of life HOWEVER…. crucial for maintaining long-term climate stability which is important for evolution of complex life.