Climate Control and Ozone Depletion

1. Climate Control and Ozone Depletion Chapter 19

2. An Enormous Cloud of Air Pollutants and Ash from Iceland volcano (April 2010) This dust cloud closed Airports in Europe for almost one week.

3. Coal Power Plant emitting green house gas

4. 19-1 How Might the Earth’s Temperature and Climate Change in the Future? • Concept 19-1 The overwhelming scientific consensus is that the earth’s atmosphere is warming rapidly, mostly because of human activities, and that this will lead to significant climate change during this century.

5. 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, and forest fire activity.

6. Estimated Changes in the Average Global Temperature of the Atmosphere Fig19-2

7. Carbon Dioxide at highest levels • In 2005, an ice core showed that CO2 levels in the troposphere are the highest they have been in 650,000 years.

8. The Natural Greenhouse Effect • Four major factors shape the earth’s climate: • The sun. • Greenhouse effect that warms the earth’s lower troposphere and surface because of the presence of greenhouse gases. • Oceans store CO2 and heat, evaporate and receive water, move stored heat to other parts of the world. • Natural cooling process through water vapor in the troposphere (heat rises).

9. Atmospheric Levels of CO2 and CH4, Global Temperatures, and Sea Levels Fig 19-4

10. Keeling Curve

11. IPCC greenhouse gases by source

12. Carbon Dioxide Trends (IPCC)

13. Animation: Greenhouse effect

14. The Atmosphere Is Warming Mostly Because of Human Activities • Intergovernmental Panel on Climate Change (IPCC) • 90–99% likely that lower atmosphere is warming • 1906–2005: Ave. temp increased about 0.74˚C • 1970–2005: Annual greenhouse emissions up 70% • Past 50 years: Arctic temp rising almost twice as fast as the rest of the earth • Melting of glaciers and floating sea ice • Prolonged droughts: increasing • Last 100 years: sea levels rose 10–20 cm • Warmer temperatures in Alaska, Russia, and the Arctic are melting permafrost releasing more CO2 and CH4 into the troposphere.

15. Melting of Alaska’s Muir Glacier between 1948 and 2004

16. The Big Melt: Some of the Floating Sea Ice in the Arctic Sea

17. The Scientific Consensus about Future Climate Change • There is strong evidence that human activities will play an important role in changing the earth’s climate during this century. • Coupled General Circulation Models (CGCMs) couple, or combine, the effects of the atmosphere and the oceans on climate.

18. Sun Troposphere Cooling from increase Greenhouse gases CO2 removal by plants and soil organisms CO2 emissions from land clearing, fires, and decay Aerosols Heat and CO2 removal Warming from decrease Heat and CO2 emissions Ice and snow cover Shallow ocean Land and soil biota Long-term storage Natural and human emissions Deep ocean Fig. 19-A, p. 502

19. CGC Models sources NASA

20. IPCC Climate Change Model

21. Comparison of Measured Temperature from 1860–2007 and Projected Changes Fig 19-b

23. Intergovernmental Panel on Climate Change (IPCC)Fourth Assessment Report 2007 Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread Melting of snow and ice and rising global average sea level (Figure SPM.1). {1.1} Most of the observed increase in global average Temperatures since the mid-20th century is very likely (p = .90) due to the observed increase in anthropogenic GHG concentrations. (Figure SPM.4). {2.4} Click for IPCC web page

24. IPCC Treatment of Uncertainty Where uncertainty is assessed more quantitatively using expert judgment of the correctness of underlying data, models or analyses, then the following scale of confidence levels is used to express the assessed chance of a finding being correct: very high confidence at least 9 out of 10; high confidence about 8 out of 10; medium confidence about 5 out of 10. Where uncertainty in specific outcomes is assessed using expert judgment and statistical analysis of a body of evidence (e.g. observations or model results), then the following likelihood ranges are used to express the assessed probability of occurrence: virtually certain >99%; extremely likely >95%; very likely >90%; likely >66%;.

26. IPCC Emissions and Equilibrium Temperatures

27. IPCC Temperature projections

28. Is a Hotter Sun the Culprit? • Since 1975 • Troposphere has warmed • Stratosphere has cooled • This is not what a hotter sun would do

29. Changing Ocean Currents • Global warming could alter ocean currents and cause both excessive warming and severe cooling.

30. Ocean Acidification Click for NRDC Acid Test Click for Ocean Acidification Network

31. FACTORS AFFECTING THE EARTH’S TEMPERATURE • Some factors can amplify (positive feedback) and some can dampen (negative feedback) projected global warming. • There is uncertainty about how much CO2 and heat the oceans can remove from the troposphere and how long the heat and CO2 might remain there.

32. There Is Uncertainty about the Effects of Cloud Cover on Global Warming • Warmer temperatures create more clouds • Thick, light-colored low altitude clouds: decrease surface temperature • Thin, cirrus clouds at high altitudes: increase surface temperature

33. Outdoor Air Pollution Can Temporarily Slow Global Warming • Aerosol and soot pollutants • Will not enhance or counteract projected global warming • Fall back to the earth or are washed out of the lower atmosphere • Reduction: especially in developed countries

34. DEALING WITH GLOBAL WARMING • Climate change is such a difficult problem to deal with because: • The problem is global. • The effects will last a long time. • The problem is a long-term political issue. • The harmful and beneficial impacts of climate change are not spread evenly. • Many actions that might reduce the threat are controversial because they can impact economies and lifestyles.

35. 19-2 What Are Some Possible Effects of a Warmer Atmosphere? • Concept 19-2 The projected rapid change in the atmosphere's temperature during this century is very likely to increase drought and flooding, shift areas where food can be grown, raise sea levels, result in intense heat waves, and cause the premature extinction of many species.

37. IPCC Projected Regional Impacts

38. IPCC Impacts Very likely = 90% probable

39. Enhanced Global Warming Could Have Severe Consequences • Tipping point and irreversible climate change • Worst-case scenarios • Ecosystems collapsing • Low-lying cities flooded • Wildfires in forests • Prolonged droughts: grasslands become dust bowls • More destructive storms • Glaciers shrinking; rivers drying up

40. Projected Effects of Global Warming and the Resulting Changes in Global Climate Fig 19-7

41. Severe Drought Is Increasing: The Browning of the Earth • Accelerate global warming, lead to more drought • Biodiversity will decrease • Net Primary Productivity (NPP) will decrease • Dry climate ecosystems will increase

42. Ice and Snow Are Melting • Europe’s Alps • Glaciers are disappearing • South America • Glaciers are disappearing • Greenland • Warmer temperatures

43. Areas of Glacial Ice Melting in Greenland during Summer 1982–2007 Increased Fig 19-c

44. Sea Levels Are Rising • Projected irreversible effect • Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs • Disruption of coastal fisheries • Flooding of • Low-lying barrier islands and coastal areas • Agricultural lowlands and deltas • Contamination of freshwater aquifers • Submergence of low-lying islands in the Pacific and Indian Oceans and the Caribbean

45. Areas of Florida, U.S., to Flood If Average Sea Level Rises by One Meter Fig19-8

46. Low-Lying Island Nation: Maldives in the Indian Ocean

47. Permafrost Is Likely to Melt: Another Dangerous Scenario • Carbon present as CH4 in permafrost soils and lake bottoms • 2004: Arctic Climate Impact Assessment • 10–20% of the permafrost might melt this century • Effect on global warming – ice reflects heat, land absorbs heat.

48. Projected Decline in Arctic Tundra in Portions of Russia from 2004 to 2100 Fig 19-10

49. Global Warming Is a Major Threat to Biodiversity • Most susceptible ecosystems • Coral reefs • Polar seas • Coastal wetland • High-elevation mountaintops • Alpine and arctic tundra

50. Effects on Biodiversity: Winners and Losers • Possible effects of global warming on the geographic range of beech trees based on ecological evidence and computer models.