Climate Change and Ozone Loss

1. Climate Change and Ozone Loss G. Tyler Miller’s Living in the Environment 15th Edition Chapter 20

2. Key Concepts • Changes in Earth’s climate over time • Factors affecting climate • Possible effects of global warming • Adapting to climate change • Human impacts on the ozone layer • Protecting and restoring the ozone layer

3. How Do We Know What Temperatures Were in the Past? Scientists analyze tiny air bubbles trapped in ice cores learn about past: troposphere composition. temperature trends. greenhouse gas concentrations. solar,snowfall, andforest fire activity. Figure 20-3

4. How Do We Know What Temperatures Were in the Past? In 2005, an ice core showed that CO2 levels in the troposphere are the highest they have been in 650,000 years. Figure 20-4

5. Past Climate Changes • Past globaltemperatures: _____ and _____. • Recent trends in global temperatures… • _________ ________.

6. The Greenhouse Effect • Greenhouse gases: _______________ Fig. 6-14 p. 110

7. Animation: Greenhouse Effect PLAY ANIMATION

8. Global Warming Potential Describes Impact of Each Gas • Carbon dioxide (CO2) has a GWP of 1 and serves as a baseline for other GWP values. CO2 remains in the atmosphere for a very long time - changes in atmospheric CO2 concentrations persist for thousands of years. • Methane (CH4) has a GWP more than 20 times higher than CO2 for a 100-year time scale. CH4 emitted today lasts for only about a decade in the atmosphere, on average.[3] However, on a pound-for-pound basis, CH4 absorbs more energy than CO2, making its GWP higher. • Nitrous Oxide (N2O) has a GWP 300 times that of CO2 for a 100-year timescale. N2O emitted today remains in the atmosphere for more than 100 years, on average.[3] • Chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) are sometimes called high-GWP gases because, for a given amount of mass, they trap substantially more heat than CO2. (EPA.gov)

9. Table 21-1Page 464 Table 21-1 Major Greenhouse Gases from Human Activities Greenhouse Gas Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Chlorofluorocarbons (CFCs)* Hydrochloro- fluorocarbons (HCFCs) Hydrofluorocarbons (HFCs) Halons Carbon tetrachloride Human Sources Fossil fuel burning, especially coal (70–75%), deforestation, and plant burning Rice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelines Fossil fuel burning, fertilizers, livestock wastes, and nylon production Air conditioners, refrigerators, plastic foams Air conditioners, refrigerators, plastic foams Air conditioners, refrigerators, plastic foams Fire extinguishers Cleaning solvent Average Time in the Troposphere 100–120 years 12–18 years 114–120 years 11–20 years (65–110 years in stratosphere) 9–390 15–390 65 42 Relative Warming Potential (compared to CO2) 1 23 296 900–8,300 470–2,000 130–12,700 5,500 1,400

10. 380 360 340 320 300 Concentration of carbon dioxide in the atmosphere (ppm) 280 Carbon dioxide 260 240 +2.5 220 0 200 Variation of temperature (˚C) from current level –2.5 180 –5.0 –7.5 Temperature change –10.0 End of last ice age 160 120 80 40 0 Thousands of years before present

11. 410 360 Parts per million 310 260 1800 1900 2000 2100 Year Carbon dioxide (CO2)

12. 2.4 1.8 Parts per million 1.2 0.6 1800 1900 2000 2100 Year Methane (CH4)

13. Fig. 20-5c, p. 467

14. Climate Change and Human Activities • Increased use of ____________ (CO2) • _________________ (CO2) • Increased number of _________ that release _____________ • Cultivation of _______ in _________ (_________ from anaerobic microbes)

15. Increasing greenhouse gases • play

16. IPCC findings that support the consensus that the troposphere is getting warmer: 20th century was the ____________ century in the past 1000 years since 1861 the average global temperature near earth’s surface has __________ 0.6 degrees C 16 warmest years on record since _________ ________________ are melting during the last century average sea level rose by 0.1-0.2 ___________ from melting ice and water volume expanding with temperature increase

17. IPCC

18. Arctic sea ice1979 (left) 2003 (right)

19. Factors Affecting the Earth’s Temperature • ___________ store CO2 and heat • __________ cover • ___________ (microscopic droplets and particles) • Plant ____________________ • Bogs, wetlands and ____________ store or release methane

20. Sun Troposphere CO2 removal by plants and soil organisms Cooling from increase CO2 emissions from land clearing, fires, and decay Green- house gases Heat and CO2 emissions Heat and CO2 removal Aerosols Warming from decrease Ice and snow cover Shallow ocean Land and soil biota Long-term storage Natural and human emissions Deep ocean Fig. 20-6, p. 469

21. Some Possible Effects of a Warmer World

22. Effects of a Warmer Atmosphere Change in _____________ and ______________ size of species ___________________ shifts Rising _________ _________

23. Rising Sea Levels During this century rising seas levels are projected to flood low-lying urban areas, coastal estuaries, wetlands, coral reefs, and barrier islands and beaches. Figure 20-10

24. High Projection New Orleans, Shanghai, and other low-lying cities largely underwater Mean Sea-Level Rises (centimeters) Medium Projection More than a third of U.S. wetlands underwater Low Projection Year Fig. 20-10, p. 475

25. Changing Ocean Currents Global warming could alter ocean currents and cause both excessive warming and severe cooling. Figure 20-12

26. Solutions: Dealing with the Threat of Climate Change Options • Do ____________ • Do more __________ – wait and see • Act now to reduce risks - ___________ ______________ • No _______ strategy Fig. 21-17 p. 479

27. Reducing the Threat Reduce fossil fuel use through ___________ _____________ Shift to renewable _________-____ energy Sequester (store) CO2 in _______, __________, ___________, _______ _________

28. Removing CO2 from the Atmosphere Fig. 21-18 p. 480

29. Reducing Greenhouse Gas Emissions • _______________ Protocol (Treaty) (1997) • _____________ withdraws from Kyoto Treaty (2001)

30. International Climate Negotiations: The Kyoto Protocol Treaty on global warming which first phase went into effect January, 2005 with 189 countries participating. It requires 38 participating developed countries to cut their emissions of CO2, CH4, and N2O to 5.2% below their 1990 levels by 2012. Developing countries were excluded. The U.S. did not sign, but California and Maine are participating. U.S. did not sign because developing countries such as China, India and Brazil were excluded.

31. The Ozone Shield • The ozone layer is in the stratosphere at an altitude of 15 to 40 km. • Ozone absorbs ultraviolet solar radiation. • Ozone is a molecule made of three oxygen atoms. • Too much UV light is harmful to organisms because it can damage the genetic material in living cells. • Ozone in the stratosphere acts like a sunscreen for the Earth’s inhabitants by shielding the Earth’s surface from most of the sun’s UV light

32. OZONE DEPLETION IN THE STRATOSPHERE Since 1976, in Antarctica, ozone levels have markedly decreased during October and November. Figure 20-20

33. Ozone Depleting Chemicals • Chlorofluorocarbons (CFCs) • Halons • Methyl bromide • Carbon tetrachloride • Methyl chloroform • Hydrogen chloride

34. Former Uses of CFCs • _________ _____________ • _____________ • _________ cans • Cleaners for ___________ parts • Sterilizing medical instruments • Fumigants for granaries and cargo ships

35. Chemicals That Cause Ozone Depletion • Each CFC molecule contains from one to four chlorine atoms, and scientists have estimated that a single chlorine atom in the CFC structure can destroy 100,000 ozone molecules.

36. Ozone Depletion in the Stratosphere Fig. 21-21 p. 484

37. Animation: How CFCs Destroy Ozone PLAY ANIMATION

38. The Ozone Hole • In 1985, studies by scientists working in Antarctica revealed that the ozone layer above the South Pole had thinned by 50 to 98 percent. • The ozone hole is a thinning of stratospheric ozone that occurs over the poles during the spring. • This was the first news of the hole, and was published in an article in the scientific journal Nature in 1985.

39. The Ozone Hole • After the results were published, NASA scientists reviewed data that had been sent to Earth by the Nimbus 7 weather satellite. They were able to see the first signs of ozone thinning in the data from 1979. • Although the concentration of ozone fluctuated during the year, the data showed a growing hole. • Ozone levels over the Arctic have decreased as well. In March 1997, ozone levels over part of Canada were 45 percent below normal. Nimbus 7

40. The Ozone Hole NASA Ozone Hole Watch

41. Seasonal Ozone Layer Thinning at the Poles • Ozone thinning (hole): • Greatest over______________ • Causes increased _________ and ____________ radiation

42. OZONE DEPLETION IN THE STRATOSPHERE During four months of each year up to half of the ozone in the stratosphere over Antarctica and a smaller amount over the Arctic is depleted. Figure 20-19

43. How Does the Ozone Hole Form? • You may be thinking, “If ozone is also being produced as air pollution, why does this ozone not repair the ozone hole in the stratosphere?” • The answer is that ozone is very chemically reactive. Ozone produced by pollution breaks down or combines with other substances in the troposphere long before it can reach the stratosphere to replace ozone that is being destroyed.

44. Loss of the Ozone Layer: Reasons for Concern • Increased incidence and severity of ___________ • Increase in _____ _____________ • Increased incidence of ________ cancer Refer to Fig. 21-23 p. 486 • __________ system suppression • Increase in _______ ____________ • Lower _____ _______ and reduced ___________

45. Natural Capital Degradation Effects of Ozone Depletion Human Health • Worse sunburn • More eye cataracts • More skin cancers • Immune system suppression Food and Forests • Reduced yields for some crops • Reduced seafood supplies from reduced phytoplankton • Decreased forest productivity for UV-sensitive tree species Wildlife • Increased eye cataracts in some species • Decreased population of aquatic species sensitive to UV radiation • Reduced population of surface phytoplankton • Disrupted aquatic food webs from reduced phytoplankton Air Pollution and Materials • Increased acid deposition • Increased photochemical smog • Degradation of outdoor paints and plastics Fig. 20-21, p. 488 Global Warming • Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases

46. Skin Cancers Fig. 21-25 p. 487

47. Effects of Ozone Thinning on Humans

48. Protecting the Ozone Layer • In 1987, a group of nations made an agreement, called the Montreal Protocol, to sharply limit their production of CFCs. • At a second conference in Copenhagen, Denmark in 1992, developed countries agreed to eliminate most CFCs by 1995. • The United States pledged to ban all substances that pose a significant danger to the ozone layer by the year 2000.

49. Solutions: Protecting the Ozone Layer • CFC substitutes • _______________ Protocol (1987) • _______________ Protocol (1992) Fig. 21-27 p. 489