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Chapter # 21 Global Climate Change

Chapter # 21 Global Climate Change. Overview. Introduction to Climate Change Causes of Global Climate Change Effects of Climate Change Melting Ice and Rising Sea Level Changes in Precipitation Patterns Effects on Organisms Effects on Human Health Effects on Agriculture

margaret-emerson
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Chapter # 21 Global Climate Change

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  1. Chapter #21Global Climate Change

  2. Overview • Introduction to Climate Change • Causes of Global Climate Change • Effects of Climate Change • Melting Ice and Rising Sea Level • Changes in Precipitation Patterns • Effects on Organisms • Effects on Human Health • Effects on Agriculture • Dealing with Global Climate Change

  3. Climate Change-Mean Annual Global Temperature 1960-2005

  4. Climate Change Terminology • Greenhouse Gas • Gas that absorbs infrared radiation • Ex: Carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and tropospheric ozone • Positive Feedback • Change in some condition triggers a response that intensifies the changed condition • Infrared Radiation • Radiation that has a wavelength that is longer than that of visible light, but shorter than that of radio waves • Greenhouse Effect • Increase of heat in a system where energy enters (often as light), is absorbed as heat, and released sometime later

  5. Climate Change • Evidence for Climate Change • 11 of the 12 years between 1995 and 2006 were among the twelve warmest years since the mid-1800s • Phenological spring in N. hemisphere now comes 6 days earlier • Warming is not due to natural causes • Human produced greenhouse gases are most plausible explanation

  6. Causes • Greenhouse gas concentrations increasing

  7. Causes • Increased concentration of CO2 (right) • Burning fossil fuels in cars, industry and homes • Deforestation • Burning of forests

  8. Greenhouse Effect

  9. Other Pollutants Cool the Atmosphere • Atmospheric Aerosols tend to cool the atmosphere • Both human and natural sources • Tiny particles that remain in troposphere for weeks or months • Contain many chemicals, but often contain sulfur • Complicates models of climate change

  10. Climate Models • Climate affected by: • winds, clouds, ocean currents, and albedo • Used to explore past climate events • Advanced models can project future warming events • Models are only as good as the data and law used to program them • They have limitations

  11. Climate Models

  12. Effects of Global Climate Change • Ocean as CO2 sink - excess CO2 is starting to harm ocean life

  13. Effects of Global Climate Change- Melting Ice and Rising Sea Levels • Sea level rise caused in 2 ways • Thermal Expansion • Water expands as it warms • Melting of land ice • Retreat of glacier and thinning of ice at the poles • Melting has positive feedback • Increased melting decreases ice, which decreases albedo leading to further warming

  14. Melting Ice and Rising Sea Levels 1957 1998

  15. Case-In-Point Impacts in Fragile Areas • Eskimo Inuit live traditional life dictated by freezing climate • Climate change is altering their existence • Wildlife are smaller or displaced • Reduced snow cover and shorter river ice seasons • Thawing of permafrost (right)

  16. Effects of Global Climate Change- Changing Precipitation Patterns • Some areas will get more water, some areas will have greater droughts • Ex: Hurricanes will likely get stronger

  17. Effects of Global Climate Change- Effects on Organisms • Zooplankton in parts of California Current have decreased by 80% since 1951 • Effecting entire food chain • Decline in krill around Antarctica • Caused decrease in penguin populations • Species have shifted their geographic range • Migrating birds are returning to summer homes earlier • Food is not available at this time

  18. Effects on Organisms - Coral Reefs • Coral reefs can be bleached (right) due to increase in water temperature • Affects coral symbiotes and makes them more susceptible to diseases to which they would otherwise be immune

  19. Effect on Organisms - VegetationBeech Tree Range

  20. Effects on Human Health • Increased number of heat-related illnesses and deaths

  21. Effects on Agriculture • Difficult to anticipate • Productivity will increase in some areas and decrease in others • Rise in sea level will inundate flood plains and river valleys (lush farmland) • Effect on pests is unknown • Warmer temperatures will decrease soil moisture- requiring more irrigation • Location (i.e. elevation and altitude) where certain crops can be grown may have to change

  22. International Implicationsof Climate Change • Developed vs. Developing countries • Differing self-interests • Differing ability to meet the challenges of climate change

  23. Dealing with Global Climate Change • To avoid the worst of climate change, CO2 levels must be stabilized at 550ppm • 50% higher than current levels • Two ways to attempt to manage climate change • Mitigation • Focuses on limiting greenhouse gas emissions to moderate global climate change • Adaptation • Focuses on learning to live with to the environmental changes and societal consequences brought about by global climate change

  24. Dealing with Global Climate Change- Relationship Between Mitigation and Adaptation

  25. Dealing with Global Climate Change- Mitigation • Locate/invent alternative fuels to fossil fuels • Increase efficiency of cars and trucks • Sequestering carbon before it is emitted • Plant and Maintain trees to naturally sequester carbon

  26. Dealing with Global Climate Change- Adaptation • Rising sea levels and coastal populations • Move inland • Construct dikes and levees • Adapt to shifting agricultural zones • NYC sewer line

  27. “There were rumors of unfathomable things, and because we could not fathom them we failed to believe them, until we had no choice it was too late.”

  28. Ozone Depletion • Stratospheric ozone • UV light • Chemical processes • Environmental effects • Solutions

  29. Atmosphere • Stratospheric ozone • 20-30 km altitude • 19 mi at equator, 9 mi at the poles • 400 ppb

  30. Ozone shield • 99% of all UV is absorbed (UVC and most UVB) • UVA is not affected by ozone

  31. Production of ozone

  32. Measurement of Ozone • Dobson units: 1 ppb ozone • Survey began in 1957 over the Antarctic • Taken in October, springtime • 1957-1970: 300 DU • 150 DU by 1986

  33. Ozone and CFC’s • Molina and Rowland in 1974 • CFC’s are stable • Long residence in lower atmosphere • UV radiation breaks down CFC and releases Cl • Cl reacts with O3 • Increase UVB at the surface

  34. Formation and destruction of ozone

  35. Emissions

  36. Usage 2003

  37. Ozone Hole

  38. Polar Stratospheric clouds • Polar winter formation • Have polar vortex • Isolated air mass • Nitrogen oxides held in clouds as nitric acid • NO3 particles grow and fall out • Facilitates ozone depleting reactions

  39. Polar vortex In Springtime, sunlight Returns No nitrate to form CloNO2

  40. Environmental effects • UV damage to DNA • Skin cancer • Cataracts • Suppression of immune system • Ecosystem: • Primary producers • Food chains • Development in aquatic larva

  41. Managing ozone depletion • Montreal protocol, Sept 1987– Production of CFC elimination • Economic gap • Replacements: HFC and HCFC • Shorter lifetime, less reactive • Collection and reuse (no venting) • Expensive replacements

  42. Climate Change • Climate Swings • Greenhouse gases • Evidence • Predictions • Control

  43. Historic Climate shifts • Milankovitch cycles: shifts in earth‘s orbit and tilt • Volcanic activity: Mt. Toba

  44. El Nino/Southern Oscillation • Trade winds keep warm water in W. Pacific. La Nina • El Nino: Shift in tropical depression • Northern Jet stream splits changes rainfall patterns • Pacific decadal oscillation: warm water in northern pacific moves back and forth. • Cool water in north help Alsaka salmon runs, warm off coast and then switches.

  45. Human Activities • Industrialization • CO2 increased 31%, CH4 inc 151%, N2O inc 17% over since pre-industrial times. • 40% of excess CO2 absorbed by oceans • Methane a big problem

  46. Evidence of Climate Change • Avg global temperature has climbed 0.6oC over last century • Arctic sea ice is 40% thinner, Antarctic glaciers are retreating 50m/yr. • Alpine glaciers are retreating • Ocean acidification • Sea level has risen • Changes in animal behavior, breeding cycles • Storm frequency and intensity are increasing

  47. Larsen B ice shelf-- Antarctica

  48. Consequences Arctic sea ice Alpine glaciers

  49. Predictions Predicted warming with doubling of CO2 Sugar maple range

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