Fundamentals

1. Fundamentals • Atmosphere • Climate Variation • Greenhouse Effect • Climate Drivers • Carbon Cycle • Energy Balance • System Inertia • Geologic time • Causes of Climate Change

2. Earth’s Atmospheric Composition, Temperatures and Pressure

3. Atmospheric Abundance of CO2 and Global Temperatures

4. Climate Shift and Temperature

5. Natural Variations of Climate during Warming

6. One Way of Causing Short-term Climate Variations

7. The Greenhouse Effect

8. Small changes in the global averagetemperatureresult in large climate changes • A 5° C drop in the global average temperature places us in the depths of an Ice Age. • An 8° C rise in the global average temperature places us near the top of a Hot House.

9. Greenhouse Gases and Percent Warming • Carbon Dioxide - CO2 (56%) • Methane - CH4 (16%) • Tropospheric Ozone - O3(12%) • Halocarbons (11%) • Nitrous Oxide - N2O (5%)

10. Climate Drivers

11. Change in Temperature with Height for 2 Amounts of CO2

13. Continental Absorption of CO2

14. Energy Balance of the Earth

16. INERTIA • General Physics…the resistance to change in some physical property of a body or system. • Global Warming…the resistance to change in direction of various elements of the climate system, such as rising atmospheric CO2, rising temperatures and melting ice.

17. Inertia in Action • CFCs have decreased dramatically during the past 20 years. • The ozone hole in 2006 was as large as ever because of the long lifetime of CFCs in the stratosphere and continuing emissions. • It will take about 70 years for the ozone hole to disappear.

18. Other Climate Basics • Feedbacks can cause the climate to move in one direction or the other independent of the original cause. • Abrupt climate changes can drive the climate very rapidly; up to 8° C in 10 years or less. • Uncertainties

19. Geologic Time Natural Causes of Climate Change and

20. Geologic Timescale Red and blue areas indicate hot (Hot House) and cold (Ice House) periods

21. The Geologic Time Scale Relative to One Year

22. Major Human Events Relative to One Year *Starting time to the present.

23. The Anthopocene Epoch • The Anthopocene is a new Epoch characterized by human-caused major global changes that have altered the Earth in fundamental ways. • It starts near the beginning of the Industrial Revolution in 1751. • We are no longer in the Holocene.

24. Some Major Changes to Earth by Humans • Changed Carbon Cycle • Climate Change • Ocean Acidification • Urbanization and Habitat Encroachment • Deforestation • Major Depletion of Marine Food Fish • Major Disruption of Land Surfaces

25. Beginning of the Anthropocene • The diagram shows some of the criteria that defines the Anthropocene. • The effects of these changes will leave a distinct stratigraphic marker.

26. Mass Extinctions • The K/T extinction was probably due to a large impact that radically changed the climate. • The other extinctions appear to be due to natural climate changes. • The greatest mass extinction (P/T) was due to a climate change from an Ice House to a Hot House.

27. Causes of Climate Change • Abundance of Greenhouse Gases • Major Volcanic Eruptions • Large Asteroid or Comet Impact • Change in Sun’s Irradiance • Change in Ocean Circulation • Continental Drift • Change in Earth’s Motions Red = main cause of current global warming

28. Past Oxygen and CO2 Abundances

29. Major Volcanic Eruptions • Large volcanic eruptions can cool the climate for a few years by injecting ash into the stratosphere to reflect the Sun’s radiation back to space. • Enormous eruptions over long periods can emit large amounts of CO2 to warm the climate.

30. Mt. Pinatubo eruption lowered the global average temperature between 0.2 and 0.6° C from mid-June 1991 and about 1995

31. Large Asteroid or Comet Impacts • Large impacts cool the climate by injecting dust into the stratosphere to reflect sunlight back to space. • If the impact is in limestone a large impact will first cool the climate and then heat it up by releasing large amount of CO2 from the limestone.

32. Changes in the Ocean’s Thermohaline Circulation Can Change the Climate

33. Continental Drift due to Plate Tectonics can Change Climate over Millions of Years

34. Changes in Earth’s Motions can Change the Climate

35. Variations in the Earth’s Insolation with Time

36. Changes in the Sun’s Irradiance

37. Soar irradiance through September 2008.Reference: Fröhlich, C. and J. Lean, Astron. Astrophys. Rev., 12, pp. 273--320, 2004. http://www.pmodwrc.ch/pmod.php?topic=tsi/composite/SolarConstant

38. Solar Irradiance Does Not Correlate with Human-caused Temperature Increase

39. Measurements of Surface Temperature and Sun’s Energy

40. Solar Irradiance, Temperature, and Atmospheric CO2

41. Solar Irradiance, Temperature, and Human-Caused CO2 Emissions

42. Conclusions • Only two causes can operate on time scales short enough to account for today’s rapid warming: 1) increase in solar irradiance, or 2) increase in greenhouse gases. • The increase in solar irradiance is not enough to account for the present warming, and does not correlate with its rapid rise. • The increase in greenhouse gases must be the primary cause of global warming. • This is consistent with the observed rapid rise in both greenhouse gases and their emission by human activities.