Chapter 19-Global Change

CORE CASE STUDY:Walking on Thin Ice

  1. Global change includes global climate change and global warming
  2. Global change occurs in the chemical, biological, and physical properties
  3. Global climate change refers to changes in the climate of Earth—the average weather that occurs in an area over a period of years or decades
  4. Global warming refers to specifically to one aspect of climate change: the warming of the oceans, landmasses, and atmosphere of Earth
  5. Solar radiation and greenhouse gases make our planet warm
  6. The Sun-Earth Heating System
  7. The sun emits most of its radiated energy in the form of high-energy visible radiation and ultraviolet radiation
  8. Earth emits most of its energy as low-energy infrared radiation
  9. About 1/3 of the radiation from the sun is reflected back into space, some UV is absorbed by the ozone layer
  10. What UV radiation and visible light that make it through the atmosphere strike clouds and the surface of the Earth where some of it is absorbed by clouds and Earth’s surface
  11. Some radiation is reflected back into space
  12. Infrared is so low energy it does not pass easily through the atmosphere and is absorbed by gases, which then warm and emit IR either back to Earth or into space
  13. The greenhouse effect is the absorption of infrared radiation by atmospheric gases and reradiation of the energy back toward Earth
  14. Over the long-term (millions of years) the system has been stable in terms of inputs and outputs of energy
  15. In the short term (decades) fluctuations in inputs have caused warmer and cooler periods on Earth over time
  16. The Greenhouse Effect
  17. Greenhouse gases absorb infrared radiation in the atmosphere and radiate much of it back toward the surface
  18. Water vapor is the most common greenhouse gas and absorbs the most infrared radiation of any compound on Earth, it does not persist nearly as long as other GHGs
  19. Other important GHGs are CO2, CH4, N2O, O3, CFCs
  20. Without GHGs our planet would be too cold for life to exist
  21. The greenhouse warming potential of a gas estimates how much a molecule of any compound can contribute to global warming over a period of 100 years relative to a molecules of CO2
  22. In calculating this potential, scientists consider 1the amount of infrared energy that given gas can absorb and 2how long a molecule of the gas can persist in the atmosphere (please see Table 19.1 on p. 521)
  23. Sources of greenhouse gases are both natural and antrhopogentic
  24. Natural Sources of Greenhouse Gases
  25. Natural sources of GHGs include volcanic eruptions, decomposition, digestion, denitrification, evaporation, and evapotranspiration.
  26. Volcanic Eruptions
  27. Many gases and ash released
  28. Ash can reflect incoming solar radiation causingglobal cooling (short-term)
  29. Methane (CH4)
  30. Anaerobic decomposition: wetlands, digestion in termites and ungulates
  31. Nitrous Oxide(N2O)
  32. Denitrification in low oxygen areas
  33. Water Vapor(H2O)
  34. Evaporation and evapotranspiration, varies regionally
  35. Anthropogenic Sources of Greenhouse Gases
  36. Use of Fossil Fuels
  37. Combustion releases fossil carbon as CO2 and black soot as carbon
  38. Coal releases most CO2, oil 85% as much, natural gas 56% as much
  39. Black soot that falls on ice and snow at higher altitudes absorbs more of the Sun’s energy by lowering the albedo, positive feedback loop because the soot becomes more concentrated as the snow and ice melts
  40. Agricultural Practices
  41. N2O, CH4 released from flooded fields because of anoxic wetland-like conditions
  42. Synthetic fertilizers, manures, and crops create and excess of nitrogen in the soil leading to N2O
  43. Livestock release large amounts of CH4
  44. Manure decomposes to release CO2under aerobic conditions and CH4under anaerobic conditions
  45. Deforestation
  46. The net destruction of vegetation will contribute to the increase in CO2because the mass of carbon that made up the trees is added to the atmosphere by combustion and decomposition
  47. Landfills
  48. Anaerobic decomposition: CH4
  49. Industrial Production of New Greenhouse Chemicals
  50. CFCs are potent GHGs, unfortunately the compounds they were replaced with—HCFCs—also have very high greenhouse warming potentials and will be phased out by 2030
  51. Ranking the Anthropogenic Sources of Greenhouse Gases
  52. CH4: digestive process of livestock, landfills, and the production of natural gas and petroleum products
  53. N2O: agricultural soil that receives nitrogen from synthetic fertilizers, applications of manure as organic fertilizer, nitrogen-fixing crops
  54. CO2: emission from burning fossil fuels
  55. Changes in CO2 and global temperatures have been linked for millennia
  56. The Intergovernmental Panel on Climate Change (IPCC) is a group of 3000 scientists from around the world that use data about gas concentrations and temperatures to predict the effects of climate change on biodiversity and energy fluxes in ecosystems, as well as the economic and social effects of climate change
  57. Increasing CO2 Concentrations
  58. Charles David Keeling began collecting CO2 measurements every month, starting in 1958, at the Mauna Loa Observatory in Hawaii
  59. CO2 levels vary seasonally (drop in spring, rise in fall) and the concentration increases year to year
  60. Emissions from the Developed versus Developing World
  61. In 2009, developing countries surpassed developed countries in the production of CO2
  62. China is now the leading emitter of CO2
  63. The leading PER CAPITA emitter is Australia
  64. Global Temperatures Since 1880
  65. The warmest decade NASA has on record is 2000-2009
  66. Temperatures have exhibited a slow increase from 1880 to today (0.8oC on average)
  67. Northern latitudes have experienced the greatest increases in temperature, with nearly 40% of the ice caps melted
  68. Global Temperatures and Greenhouse Gas Concentrations During the Past 400,000 Years
  69. Indirect measurements of climate change include 1changes in the species composition of organisms that have been preserved over millions of years and 2chemical analyses of ice that was formed long ago
  70. Marine sediments contain shells of foraminiferas, each species prefer different water temperatures
  71. Ice cores contain trapped air bubbles of ancient air, going back 500,000 years
  72. Scientists can analyze the GHGs released when they melt a section of the core, as well as, measure the percent composition of the isotopes of oxygen
  73. Recent Temperature Increases
  74. One possible explanation is natural fluctuations in the solar cycle have released more solar radiation, this could be working synergistically with increased CO2 levels
  75. Climate Models and Future Conditions
  76. Computer models incorporate air and ocean temperatures, CO2 concentration, extent of vegetation, and sea ice coverage at the poles
  77. Assumptions vary among different climate models, scientists think we will have between 1.8oC and 4oC increase by 2100
  78. Feedbacks can increase or decrease the impact of climate change
  79. Positive Feedbacks
  80. When Earth is warmer the ocean cannot hold as much CO2, which is then released into the atmosphere, warming the atmosphere even more
  81. Higher temperatures are expected to increase activity of decomposers in the soil, releasing more CO2and raising the atmospheric temperature even more
  82. As Arctic regions become warmer and the tundra begins to thaw, creating standing water with little O2, leading to anaerobic decomposition and large amounts of CH4released
  83. Negative Feedbacks
  84. An increase in CO2 can stimulate plant growth, taking more CO2 out of the atmosphere and causing increase in temperature to be smaller
  85. The Limitation of Feedbacks
  86. Limitations include: amount of carbon in soils, amount of CO2 plants can take up (water & nutrients are usually limiting factors)
  87. More water vapor evaporates with warmer temperatures, leading to further warming, but there is a limit (due to the water cycle) of the amount of water vapor that can be in the atmosphere
  88. Also, more water vapor in the atmosphere leads to more cloud formation which can reflect more solar radiation back into space
  89. Global warming has serious consequences for the environment and organisms
  90. Effects already happening: melting of polar ice caps, glaciers, and permafrost and rising sea levels
  91. Effects predicted to occur: increased frequency of heat waves, reduced cold spells, altered precipitation patterns and storm intensity, and shift ocean currents
  92. Consequences to the Environment
  93. Polar Ice Caps
  94. Arctic has already warmed 1oC to 4oC, expected to warm by an additional 4oC to 7oC, Greenland & Antarctica also warming
  95. Cause large openings in the sea ice, could open new shipping lanes, expose undiscovered oil and natural gas
  96. Large amounts of melted ice cause sea levels to rise
  97. Glaciers
  98. Glacier National Park has gone from 150 to 25 glaciers and all are estimated to be gone by 2030
  99. Some communities rely on the summer melt for water
  100. Annual winter build up has been less than summer melt, could lead to water shortages for these communities
  101. Permafrost
  102. Melting causes overlying lakes to become smaller as the lake drains deeper down into the ground
  103. Melting causes problems with human-built structures that are anchored into the permafrost
  104. Melting also means massive amounts organic matter to decompose & release CH4, causing a positive feedback loop of warming & melting
  105. Sea Levels
  106. The water from melting glaciers and ice sheets on land adds to the total volume of ocean water
  107. As the water of the oceans become warmer, it expands
  108. Sea levels have risen 9 inches since 1870, scientists predict sea levels will rise 7-23 more inches by the end of the century
  109. Endanger coastal cities & low-lying islandsmaking them more vulnerable to flooding, saltwater intrusion, and increased soil erosion
  110. Heat Waves
  111. Longer hot spells cause an increased energy demand for air conditioning, increased risk of death where air conditioning is not available
  112. Cause heat and drought damage to crops, increasing the need for irrigation which would cause a rise in food prices
  113. Cold Spells
  114. Fewer extremely cold days and days below freezing could lead to:
  115. fewer deaths
  116. a decrease in the risk of crop damage
  117. may make new areas available for agriculture
  118. decrease the energy needed to heat buildings
  119. a decrease in the die-back of some pest species, allowing their populations and range to expand
  120. Precipitation Patterns
  121. Warmer temperatures should drive increased evaporation
  122. Computer models predict some regions will receive more precipitation (recharge aquifers, higher crop yields, flooding, landslides, soil erosion) and others will receive less (difficult to grow crops, greater effort needed to supply water)
  123. Storm Intensity
  124. Unusually warm waters are predicted make hurricanes more powerful and occur more often and further north
  125. Ocean Currents
  126. Global ocean currents may shift as a result of more fresh water being released from melting ice
  127. This could lead to a disrupted distribution of heat on the planet
  128. Scientists are particularly concerned about the thermohaline circulation
  129. Increased melting from Greenland and the northern polar ice cap could dilute the salty ocean water to stop the water from sinking near Greenland and shut off thermohaline circulation, causing Europe to experience colder temperatures
  130. Consequences to Living Organisms
  131. Wild Plants and Animals
  132. The IPCC has concluded that the growing season for plants has lengthened by 4 to 16 days over the last 40 years in the Northern Hemisphere
  133. Historically, organisms have migrated in response to climatic changes.
  134. Today, fragmentation of habitats has made movement more difficult
  135. The decline of the pied flycatcher populations and coral “bleaching” are two examples of organisms that have been affected by global warming
  136. Humans
  137. People may have to move from coastal areas, however unsuitable areas may become suitable for human habitation
  138. Temperature limited disease vectors (ex. Mosquitoes) could spread beyond their current range
  139. Places that relied on snow or coral reefs for tourism could be economically damaged
  140. The Controversy of Climate Change
  141. Most scientists agree that GHG concentrations are increasing and this will lead to global warming, how much temperatures will change is unclear
  142. The Kyoto Protocol addresses climate change at the international level
  143. In 1997, representatives of the nations of the world convened in Kyoto, Japan to discuss how to control emissions contributing to global warming.
  144. The Kyoto Protocol states that global emissions of GHGs would be reduced to 5.2% below their 1990 levels by 2012 by developed countries ONLY
  145. We should take measure to stabilize greenhouse gas concentrations either by 1reducing emissions or by 2removing the gases from the atmosphere
  146. 1Increase fuel efficiency or switching from coal & oil to natural gas, solar, wind, or nuclear energy
  147. 2carbon sequestration involves taking CO2out of the atmosphere by growing new vegetation or actually capturing the CO2, compressing it, and pumping it into abandoned oil wells or deep in the ocean
  148. The US Senate voted not to sign the Kyoto Protocol, Gore signed it anyway but Clinton did not send it to the Senate for ratification
  149. The Kyoto Protocol was modified in 2001 but the US still would not sign because the same restrictions were not put on ALL nations
  150. In 2007, the Supreme Court ruled the EPA was required to regulate GHGs under the Clean Air Act
  151. In 2010, an increase in CAFÉ (Corporate Average Fuel Economy) Standards were proposed to increase fuel efficiency in cars by 30% by 2016, driving up car costs but saving the driver in fuel costs
  152. As of 2010, 190 countries have ratified the Kyoto Protocol, excluding the US

WORKING TOWARD SUSTAINABILITY: Local Governments and Businesses Lead the Way on Reducing Greenhouse Gases

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