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Global Climate Change - PowerPoint PPT Presentation


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Global Climate Change. Findings from the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC). Warming. The Climate System. Effects of global warming on water cycle. Global warming (temperature increase). Speeds up global water cycle.

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Global Climate Change


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    Presentation Transcript
    1. Global Climate Change Findings from the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) Warming

    2. The Climate System

    3. Effects of global warming on water cycle Global warming (temperature increase) Speeds up global water cycle • More extreme weather events • Droughts • Storms • Floods

    4. Potential Climate Change Impacts Health Weather-related mortality Infectious diseases Air-quality respiratory illnesses Agriculture Crop yields Irrigation demands Climate Changes Forests Change in forest composition Shift geographic range of forests Forest health and productivity Temperature Precipitation Water Resources Changes in water supply Water quality Increased competition for water Sea Level Rise Coastal Areas Erosion of beaches Inundation of coastal lands Costs to protect coastal communities Species and Natural Areas Shift in ecological zones Loss of habitat and species Source: EPA

    5. Clear correlation between atmospheric CO2 and temperature over last 160,000 years • Current level of CO2 is outside bounds of natural variability • Rate of change of CO2 is also unprecedented Source: OSTP

    6. If nothing is done to slow greenhouse gas emissions. . . • CO2 concentrations will likely be more than 700 ppm by 2100 • Global average temperatures projected to increase between 2.5 - 10.4°F 2100 Source: OSTP

    7. Tree-ring Records

    8. Sediments Records

    9. Source: OSTP

    10. +1.4~5.8°C +0.10~0.85cm

    11. Responses to Global Warming Coastal line

    12. Glacier Retreat 1930 2001

    13. Weather Change

    14. Deforestation Source: OSTP

    15. Palmer Drought Severity Index (The Palmer; PDSI)

    16. Potential Climate Change Impacts Health Weather-related mortality Infectious diseases Air-quality respiratory illnesses Agriculture Crop yields Irrigation demands Climate Changes Forests Change in forest composition Shift geographic range of forests Forest health and productivity Temperature Precipitation Water Resources Changes in water supply Water quality Increased competition for water Sea Level Rise Coastal Areas Erosion of beaches Inundation of coastal lands Costs to protect coastal communities Species and Natural Areas Shift in ecological zones Loss of habitat and species Source: EPA

    17. Source: OSTP

    18. The Greenhouse Effect • The earth's "greenhouse effect" is what makes this planet suitable for life as we know it. • The earth's atmosphere contains trace gases, some of which absorb heat. These gases (water vapor, carbon dioxide, methane, ozone, and nitrous oxide) are referred to as "greenhouse gases." • Albedo has an important influence on the earth's temperature. • Greenhouses are structures designed to retain heat. • The heat-trapping ability of a greenhouse is influenced by a number of factors including the transparency of the greenhouse cover, color of the surfaces inside the greenhouse, and type of surfaces inside.

    19. Venus is too hot, Mars is too cold, and Earth is just right.

    20. Solar radiation interacts with the surface of the earth in several ways. Some portion of this energy is reflected back into space by the earth's atmosphere, another portion is dispersed and scattered by the molecules in the atmosphere and a large portion penetrates through the earth's atmosphere to reach the surface of the earth. The radiation reaching the earth's surface is largely absorbed resulting in surface warming.

    21. Much of this absorbed energy is eventually re-radiated in longer infrared wavelengths. As it leaves the earth, it once again interacts with the atmosphere. Some of this re-radiated energy escapes to space, but much of this re-radiated energy is reflected back to the earth's surface by molecules in the earth's atmosphere. This reflected energy further warms the surface of the earth.    

    22. The molecules responsible for this phenomenon are called greenhouse gases, i.e. water (H2O), nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) because they act like the glass in a greenhouse, trapping re-radiated energy. Without these gases most life on earth would not be possible, as the surface temperature of the earth would likely be about 60°F colder.

    23. In essence, greenhouse gases act like an insulator or blanket above the earth, keeping the heat in. Increasing the concentration of these gases in the atmosphere increases the atmosphere's ability to block the escape of infrared radiation. In other words, the earth's insulator gets thicker. Therefore too great a concentration of greenhouse gases can have dramatic effects on climate and significant repercussions upon the world around us. Climates suitable for human existence do not exist simply above some minimum threshold level of greenhouse gas concentration, rather they exist within a finite window - a limited range of greenhouse gas concentrations that makes life as we know it possible.

    24. Major Greenhouse Gases • Carbon Dioxide (CO2) • Methane (CH4) • Nitrous Oxide (N2O) • Chlorofluorocarbons (CFCs)

    25. Carbon Dioxide (CO2) The global Carbon Dioxide budget is complex and involves transfer of CO2 between the atmosphere, the oceans, and the biosphere. Since CO2 is chemically inert, it is not destroyed by photochemical or chemical processes in the atmosphere; either it is lost by transfer into the ocean or biosphere or it builds up in the atmosphere.

    26. Carbon Dioxide Carbon Dioxide Up More Than 30% Since 1750 Each year we add more than 30 billion tons of carbon dioxide to the air mainly by: • Burning fossil fuels • Cutting down and burning trees

    27. Carbon Dioxide on the Rise Since 1750, carbon dioxide in the air has risen by more than 30%, due to human activities. It could double by the year 2065.

    28. Methane (CH4) Methane can be destroyed in the atmosphere via reaction with the hydroxyl radical (OH). The major anaerobic environments that produce CH4 include wetlands (150 +/- 50 Tg/yr), rice paddies (100 +/- 50 Tg/yr), and enteric fermentation in the digestive system of cattle, sheep, ect. (100-150 Tg/yr).

    29. CH4: Methane Methane More Than Doubled Since 1750Each year we add 350 to 500 million tons of methane to the air mainly by: • Raising livestock • Coal mining and drilling for oil and natural gas • Rice cultivation • Disposing of garbage in landfills • Burning forests and fields

    30. Methane on the Rise Since 1750, methane in the air has more than doubled due to human activity. It could double again by 2050.

    31. Nitrous Oxide (N2O) Nitrous oxide is chemically inert in the troposphere. However, N2O is destroyed in the stratosphere via photolysis by solar radiation, which is responsible for about 90% of its destruction, and by reaction with excited atomic oxygen, O(1D), which is responsible for about 10% of its destruction.

    32. N2O: Nitrous Oxide Nitrous Oxide Up More Than 15% Since 1750 Three main kinds of fluorocarbons make the largest contributions to the greenhouse effect: Chemical Fertilizers: The Main Source Nitrogen-based fertilizer use has doubled in the past 15 years. Sewage Emits Nitrous OxideHuman and animal wastes release nitrous oxide. Sewage treatment plants may be a major source of this gas.

    33. Nitrous Oxide on the Rise Since 1750, nitrous oxide in the atmosphere has risen by more than 15 percent.

    34. Chlorofluorocarbons (CFC-11 and CFC-12) CFC-11 and CFC-12 are chemically inert in the troposphere and diffuse up to the stratosphere, where they are destroyed by photolysis by solar radiation and by reaction with excited atomic oxygen.

    35. Fluorocarbons Fluorocarbons Come Almost Entirely From Human Activities Three main kinds of fluorocarbons make the largest contributions to the greenhouse effect: • CFCs (chlorofluorocarbons) destroy ozone. Their use is being phased out. • HCFCs (hydrochlorofluorocarbons) destroy ozone, although less than CFCs. They are also being phased out. • HFCs (hydrofluorocarbons) do not destroy ozone, but still trap heat in the atmosphere.

    36. Climate Feedbacks on an Enhanced Greenhouse Effect • Ocean • Vegetation • Clouds & Water Vapor • Sea Ice