Studying Climate Change

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Studying Climate Change

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  1. Studying Climate Change

    Slide 1 - Studying Climate Change

    • Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
  2. Studying climate change: Ice cores

    Slide 2 - Studying climate change: Ice cores

    • Ice caps and glaciers accumulated over thousands or millions of years.
    • They contain bubbles of gas preserved from the time when each layer formed.
    • Scientists drill cores and analyze the gas bubbles in each layer to see what the atmosphere was like then.
  3. Studying climate change: Pollen analysis

    Slide 3 - Studying climate change: Pollen analysis

    • Scientists also drill cores into the sediments of ancient lake beds.
    • By identifying types of pollen grains in each layer, they can tell what types of plants were growing there at the time.
    • Sources of this type of indirect evidence are proxy indicators.
  4. Studying climate change: Direct sampling

    Slide 4 - Studying climate change: Direct sampling

    • Scientists have recorded carbon dioxide levels in the atmosphere directly since 1958, at a station in Hawaii.
    • The data show a steady upward climb from 315 to 373 ppm.
    • (The up and down zigzags are from regular winter-summer fluctuations.)
  5. Studying climate change: Modeling

    Slide 5 - Studying climate change: Modeling

    • Computer simulations that use known behavior of past climate to analyze how climate should behave as variables are changed
    • Coupled general circulation models (CGCMs) are models that combine, or couple, the effects of both atmosphere and ocean.
    • To predict what will happen to climate in the future, scientists use climate models:
  6. Studying climate change: Modeling

    Slide 6 - Studying climate change: Modeling

    • Today’s highly complex CGCMs incorporate many factors in order to predict future climate changes.
  7. Studying climate change: Modeling

    Slide 7 - Studying climate change: Modeling

    • Natural or anthropogenic factors ONLY = poor fit.
    • BOTH types of factors = excellent fit.
  8. Climate change and the IPCC report

    Slide 8 - Climate change and the IPCC report

    • In 2001, the world’s climate scientists combined to produce the single most comprehensive and authoritative research summary on climate change:
    • The Third Assessment Report of the
    • Intergovernmental Panel on Climate Change (IPCC),
    • which summarized all scientific data on climate change, future predictions, and possible impacts.
  9. Climate change and the IPCC report

    Slide 9 - Climate change and the IPCC report

    • First, the IPCC report established that global temperature is rising.
    • Direct measurements from thermometers since 1860 demonstrate this.
  10. Climate change and the IPCC report

    Slide 10 - Climate change and the IPCC report

    • Proxy indicators of temperature (from pollen, ice cores, etc.) were reviewed to establish ancient temperatures.
    • These data (BLUE) overlapped with the direct temperature measurements (RED). (Gray shows statistical uncertainty.)
  11. The IPCC report

    Slide 11 - The IPCC report

    • The IPCC also reported findings on physical changes:
    • • Average sea level increased 10–20 centimeters (4–8 inches) during 20th century.
    • • 2 weeks less ice cover on northern lakes and rivers.
    • • Arctic sea ice thinned 10–40% in recent decades.
    • • Mountain glaciers melted back worldwide.
    • • Snow cover decreased 10% since satellite observations began.
    • • Growing season lengthened 1–4 days each decade over the past 40 years.
  12. The IPCC report

    Slide 12 - The IPCC report

    • Biological changes were also found by the IPCC:
    • • Geographic ranges of many species have shifted toward the poles and up in elevation.
    • • In spring, plants are flowering earlier, birds migrating earlier, animals breeding earlier, and insects emerging earlier.
    • • Coral reefs are “bleaching” more frequently.
  13. Sea-level rise

    Slide 13 - Sea-level rise

    • Global warming is causing glaciers to shrink and polar ice shelves to break away and melt.
    • The increased flow of water into the oceans lead to sea level rise.
    • Sea level is also rising because ocean water is warming, causing water to expand in volume.
    • Higher sea levels lead to beach erosion, coastal flooding, intrusion of saltwater into aquifers, etc.
  14. Sea-level rise

    Slide 14 - Sea-level rise

    • Storm surge = temporary and localized rise in sea level caused by high tides and winds associated with storms
    • Storm surges impact small islands as well as low-lying coastal areas in countries like the U.S.
    • This vulnerability became dramatically apparent in 2005 when Hurricane Katrina struck New Orleans and the Gulf Coast of the U.S.
  15. Sea-level rise

    Slide 15 - Sea-level rise

    • A 51-centimeters (20-inches) sea level rise would inundate wetlands (red) and drylands (orange) on all U.S. coasts.
  16. Sea-level rise

    Slide 16 - Sea-level rise

    • Areas on all U.S. coasts would suffer erosion.
    • Dramatic flooding from storm
    • events like Hurricane Katrina
    • could become more frequent.
  17. Climate change predictions: Impacts

    Slide 17 - Climate change predictions: Impacts

    • The IPCC and other groups have predicted future impacts of climate change. Predictions for the U.S. include:
    • • Temperature will rise 3–5°C (5–9°F).
    • • Droughts, floods, snowpack decline, and water shortages will create diverse problems.
    • • Temperature extremes will cause health problems; tropical diseases will move north into the U.S.
    • • Sea level rise will flood coastal wetlands, real estate.
    • • Ecosystems will be altered; some will disappear.
    • • Agriculture and forestry may have mixed results.
  18. Predicted U.S. impacts

    Slide 18 - Predicted U.S. impacts

    • The Canadian model (a) predicts Illinois to be warmer and drier in the future. The Hadley model (b) predicts a warmer and moister climate.
  19. Predicted U.S. impacts: Forest types change

    Slide 19 - Predicted U.S. impacts: Forest types change

    • Distribution of forest types will change
    • Current
    • 2 future scenarios
  20. Predicted U.S. impacts: Heat index rises

    Slide 20 - Predicted U.S. impacts: Heat index rises

    • Two models show big increases in July heat index for the next 100 years, especially in the central and southeast U.S.
    • (Heat index combines temperature and humidity.)
  21. Predicted U.S. impacts: Mortality

    Slide 21 - Predicted U.S. impacts: Mortality

    • Deaths from summer heat waves will increase.
  22. Emissions reduction: More efficient generation and usage

    Slide 22 - Emissions reduction: More efficient generation and usage

    • Electricity generation is the biggest source of greenhouse gas emissions in the U.S.
    • So solutions include:
    • • Improved technology at plants
    • • Cleaner-burning coal
    • • Energy conservation by consumers
  23. Emissions reduction: Renewable energy

    Slide 23 - Emissions reduction: Renewable energy

    • Another solution is to switch to renewable energy sources:
    • Hydroelectric power
    • Geothermal energy
    • Photovoltaic cells
    • Wind power
  24. Emissions reduction: So many cars

    Slide 24 - Emissions reduction: So many cars

    • Transportation: the 2nd largest source of greenhouse gases.
    • 1/3 of average U.S. city devoted to cars
    • Average U.S. family makes:
    • 10 car trips/day
    • $200 million/day on road construction and repair
    • Number of cars in U.S. will soon exceed number of people
  25. Emissions reduction: Inefficient autos

    Slide 25 - Emissions reduction: Inefficient autos

    • Cars use energy very inefficiently. We could do better.
  26. Emissions reductions: Biking and walking

    Slide 26 - Emissions reductions: Biking and walking

    • Reducing automobile usage would also lower emissions.
    • More and more people are choosing to live closer in and bike or walk to work.
    • If Americans used public transportation at the rate Europeans do, the U.S. would no longer need Saudi Arabian oil.
  27. Emissions reductions: Public transportation

    Slide 27 - Emissions reductions: Public transportation

    • Using public transportation like buses and trains lowers emissions of many pollutants … which has a public health benefit as well.
  28. Emissions Reductions: International Treaties

    Slide 28 - Emissions Reductions: International Treaties

    • 1992: UN Framework Convention on Climate Change
    • Voluntary approach; nations were asked to cut emissions
    • Failed
    • 1997: Kyoto Protocol drafted
    • By 2012, reduce 6 greenhouse gases to below 1990 levels
  29. Emissions Reductions: Kyoto Protocol

    Slide 29 - Emissions Reductions: Kyoto Protocol

    • Reductions required under Kyoto are scaled to nations’ contributions.
    • Germany decreased emissions 18.9% while its economy grew strongly.
  30. Emissions Reductions: Kyoto Protocol

    Slide 30 - Emissions Reductions: Kyoto Protocol

    • The Kyoto Protocol has been ratified by 127 nations, enough to make it binding.
    • The U.S. continues to refuse to ratify the treaty.
  31. Emissions reductions: Kyoto Protocol

    Slide 31 - Emissions reductions: Kyoto Protocol

    • Supporters and opponents of Kyoto agree, however, that the treaty alone is not enough to turn around greenhouse gas production worldwide—it would just slow it down.
    • Developing nations say industrialized nations like the U.S. created the problem, so they should be the ones to take the lead in cleaning it up.
    • The U.S. administration has said the treaty is unfair because it does not force developing nations like India and China to share in the burden of reducing emissions.
  32. Conclusion

    Slide 32 - Conclusion

    • Many factors shape global climate.
    • Scientists and policymakers are beginning to understand anthropogenic climate change and its impacts more fully.
    • Many scientists and policymakers are deeply concerned.
    • As time passes, fewer experts are arguing that the changes will be minor.
    • Sea-level rise will affect developed and developing countries alike.