Chapter 19 Global Change

1. Chapter 19 Global Change

2. Global Change • Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. • Global climate change- changes in the climate of the Earth. • Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth.

4. The Sun-Earth Heating System • Sun Input • Absorption • Earth Output Net Flux = ZERO

6. The Greenhouse Effect • When radiation from the sun hits the atmosphere, 1/3 is reflected back. • Some UV radiation is absorbed by the ozone layer and strikes the Earth where it is converted into low-energy infrared radiation. • The infrared radiation then goes back toward the atmosphere where it is absorbed by greenhouse gasses that radiate most of it back to the Earth.

7. Greenhouse Gases • Water vapor • Absorbs and releases energy • Carbon dioxide • Methane • Nitrous oxide • Ozone • CFCs

8. Greenhouse warming potential—ratio of how much a molecule of a compound can contribute to global warming over 100 years compared to 1 molecule of CO2

9. Natural Greenhouse Gases • Volcanic eruptions • CO2—long term effects • PM—shorter term

10. Natural Greenhouse Gases • Methane • Anaerobic decomposition (wetlands) • Organism digestion

11. Natural Greenhouse Gases • Nitrous oxide • Denitrification • NO3- N2O • Low oxygen

12. Natural Greenhouse Gases • Water vapor • Most abundant • Greatest contributor

13. Anthropogenic Causes of Greenhouse Gases

14. Anthropogenic Causes of Greenhouse Gases • Burning of fossil fuels • Trapped reserves of CO2 • Coal v. Petroleum v. Natural gas • PM • Cooling or heating?

15. Anthropogenic Causes of Greenhouse Gases • Agricultural practices • Anaerobic conditions (CH4 and N2O) • Irrigation • Fertilizers • NitratesN2O • Livestock • Digestion • Manure lagoons

16. Anthropogenic Causes of Greenhouse Gases • Deforestation…without replacement • Plants remove CO2 • Slash-and-burn (shifting agriculture)

17. Anthropogenic Causes of Greenhouse Gases • Landfills • Anaerobic methane generation

18. Anthropogenic Causes of Greenhouse Gases • Industrial production • “New”/synthetic GHGs • CFCs replaced by HCFCs

20. Resisting Change • Other Pollutants Cool the Atmosphere • known as the “aerosol” effect • Sulfur emissions • Volcanic Eruptions • Jet Contrails • Increased cloud cover from evaporation • Increased absorption of CO2 in ocean’s

21. Increasing CO2 Concentrations • David Keeling began measuring CO 2 in 1958.

22. Increasing CO2 Concentrations Winter High & Summer Low

24. DO THE MATH Projecting Future Increases in CO2 • From 1960 to 2010, [CO2] rose from 320 to 390 ppm. • Based on this, what has been the average annual increase of CO2 in the atmosphere? • Based on your answer, what [CO2] do you predict for the year 2100? • From 2000-2010, the rate of increase was actually faster (1.9ppm). Based on this rate, what would you predict for the [CO2] in 2100?

25. Emissions from the Developed and Developing World

26. Global Temperatures since 1880 • Since 1880 temperatures have increased 0.8°C.

28. Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years • Indirect measurements—lack of records • Changes in species compositions • Chemical analyses of ice

30. Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years

31. Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years

32. Evidence of Global Climate Change 1. Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century. 2. Average Arctic temperatures increased at almost twice the global average rate in the past 100 years. Shrinking glaciers and ice caps. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. Despite an unusually deep solar minimum in 2007-2009 Seasonal events starting earlier and ending later The top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969 The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.

33. Recent Temperature Increases • Separating anthropogenic from natural • Increased solar radiation? • Natural fluctuations in solar radiation? • Changes in Earth’s orbit? • Changes in axis tilt and wobble? • Milankovitch cycles

34. By 2100, global increase of 1.8-4C…depends on how fast CO2 emissions grow

35. Feedbacks

36. Feedbacks • POSITIVE • High C in soil • High temperatures •  decomposition •  CO2 in atmosphere • Tundra warms • Anaerobic decomposition • CH4 • NEGATIVE • High CO2 •  plant growth • Removes CO2

37. Consequences to the Environment From Global Warming • Melting of polar ice caps, Greenland and Antarctica • Melting of many glaciers around the world • Melting of permafrost

38. Major Ice Caps - Anarctica 1. Antarctica • 90% of world’s ice • Landmass based • Larsen B Ice Shelf, 650 feet thick about the size of Rhode Island • Ross Ice Shelf, big as Texas – attached to the ice sheets that cover almost 98% of the Antarctic continent.

39. Major Ice Caps - Greenland 2. Greenland • Sea levels rise 23 feet if the entire ice sheet melted • Landmass Based

40. Major Ice Caps - The Arctic 3. The Arctic • Temperature rise of 4-7C by 2100 • All Ice Shelves

41. Melting Glaciers

42. Permafrost

43. Rising Sea Levels Thermal expansion Additions of water from melting ice

44. Consequences to the Environment From Global Warming • Heat waves • Cold spells • Change in precipitation patterns • Hardest to predict • Increase in storm intensity • Shift in ocean currents

45. Consequences to Living Organisms • Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates.

46. Consequences to Living Organisms • Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences.

47. Consequences to Living Organisms

48. Benefits of Global Warming Access to oceans for fishing and oil Increased plant production More livable climates such as twin cities

49. The Controversy of Climate Change • The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists. • What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops.