The Earth System

1. The Earth System

2. Earth: An overview • 4 main spheres • Hydrosphere (hydro=water) • Biosphere (bio=life) • Atmosphere (gas, air) • Geosphere (geo=Earth)

3. So far we have focused on the geosphere: • The Earth; • age • Pangea • Structure • Plate tectonics • Rock cycle

4. Now we will study the Atmosphere • Mixture of gases that surround Earth • There are 4 layers in the atmosphere that are divided based on their temperature gradient. • troposphere, • stratosphere • mesosphere, • thermosphere

7. 4 Layers 1) Troposphere – layer in which we live; Weather phenomena (clouds) occur here. • It’s elevation ranges from 0 to 10 km 2) Stratosphere – above troposphere; temperatures increase with altitude. • This layer contains the ozone layer, which protects us from harmful sunlight

8. What are the layers in the atmosphere? (cont…) • Mesosphere – coldest layer of atmosphere • Thermosphere – uppermost layer; temperatures also increases with altitude. • This is where most small meteorites burn up • the location in the atmosphere that the northern lights occur (aurora borealis)

9. Structure of the Atmosphere Thermosphere Mesosphere Ozone Maximum Stratosphere Troposphere Temperature

10. Energy in the Earth System

11. In the Earth system… Energy Flows Matter Cycles Life Webs

12. Energy flows in waves

13. Energy flows, and is lost

14. Energy flows in the Universe A hotter radiating body emits shorter wavelengths. A cooler body emits longer wavelengths.

15. diagram

16. Notice only about 50% of the solar energy directed at the Earth penetrates to the surface. • The rest was absorbed or reflected by the atmosphere.

17. The Earth emits heat

18. Electromagnetic Spectrum incoming outgoing

19. 1. Shorter, high energy wavelengths hit the earths surface • 2. Incoming energy is converted to heat

20. 3. Longer, infrared Wavelengths hit greenhouse gas molecules in the atmosphere • 4. Greenhouse gas molecules in the Atmosphere emit Infrared radiation back towards earth

22. 78% nitrogen 20.6% oxygen < 1% argon 0.4% water vapor 0.036% carbon dioxide traces gases: Ne, He, Kr, H, O3 Methane, Nitrous Oxide

23. The “Greenhouse Effect” • The Earth’s surface thus receives energy from two sources: the sun & the atmosphere • As a result the Earth’s surface is ~33C warmer than it would be without an atmosphere Greenhouse gases are transparent to shortwave but absorb long wave radiation • Thus the atmosphere stores energy

24. Greenhouse Effect • Warms Earth • Needed for life to thrive • Gases: • water vapor carbon dioxide methane, and nitrous oxide

25. Recent changes in greenhouse gas concentrations • What factors contribute to enhanced greenhouse effect? • What studies are being done? • Are human activities causing Earth to warm?

27. Antarctica from space

28. Antarctica

29. Antarctica is covered by ice

30. How snow is squeezed into ice

31. How an ice sheet is made

32. Antarctic ice

33. How thick is this ice sheet?

34. Layered ice

35. The ice core drill rig

36. The ice core

37. Layers in ice cores

38. Handling ice cores

39. Studying ice cores

40. Ice core sites in Antarctica Vostok

43. Selected Greenhouse Gases • Carbon Dioxide (CO2) • Source: Fossil fuel burning, deforestation • increase:30% • Methane (CH4) • Source: Rice cultivation, cattle & sheep ranching, decay from landfills, mining • increase:145% • Nitrous oxide (N2O) • Source: Industry and agriculture (fertilizers) • increase:15%

44. So, which human activities may be major causes of increasing global temperatures? • The burning of fossil fuels • Deforestation (taking out forests) • Why? • Increase of Carbon Dioxide in the atmosphere because it absorbs long wave radiation (heat), thus preventing the heat from escaping.

45. Summary Greenhouse gases absorb infrared radiation and prevent it from escaping to space. Carbon dioxide, methane, and nitrous oxide are very good at capturing energy at wavelengths that other compounds miss

46. Greenhouse Effect & Global Warming • The “greenhouse effect” & global warming are not the same thing. • Global warming refers to a rise in the temperature of the surface of the earth • An increase in the concentration of greenhouse gases leads to an increase in the themagnitude of the greenhouse effect. (Called enhanced greenhouse effect) • This results in global warming

47. Climate Change vs. Variability • Climate variability is natural. • Even in a stable climate regime, there will always be some variation (wet/dry years, warm/cold years) • A year with completely “average” or “normal” climate conditions is rare. • The challenge for scientists is to determine whether any increase/decrease in precipitation, temperature, frequency of storms, sea level, etc. is due to climate variability or climate change.

48. Effects of Ozone Depletion

49. TheDiscovery • In 1985, using satellites, balloons, and surface stations, a team of researchers had discovered a balding patch of ozone in the upper stratosphere, the size of the United States, over Antarctica. British Atlantic Survey Research station, Holly Bay, Antarctic coast Team who discovered the hole 1985. From left: Joe Farman, Brian Gardiner, and Jonathan Shanklin

50. Earth’s Atmosphere