Download pdf for the latest version of this lecture/discussion. (11/29/05)

Download pdf of Science paper. (11/29/05)

Use up to 6 powerpoint slides (plus a word slide to bullet your points if needed) to discuss the following in terms of (1) factors involved, (2) climate impacts, (3) human impacts (health, agriculture, urban areas), (4) uncertainties

Group 1: Natural climate change
Group 2: Projected trends in CO2
Group 3: Trends in temperature with doubling CO2
Group 4: Trends in sea level with global warming
Group 5: Arctic's role in global climate change

The following is a list, in outline form, of aspects you may want to consider in your discussion. Additionally, you may want to use figures from lecture notes (powerpoint), and try to consider all of the aspects of climate that have been covered during the semester.

I. Climate Change Scientific Uncertainties.

II. Climate Change Impacts.

  1. Physical Environment

    1. Temperature
      • Global average temperature is expected to increase by 1.4-5.8°C from 1990-2100
      • High end increase due to likely SO2 reduction
      • Land warms faster than the oceans
      • Greater warming in high latitudes
      • Smaller surface air temperature increase in North Atlantic and Circum-Antarctic
      • Decrease in diurnal temperature range - nighttime lows increasing more than daytime highs
      • More heat waves, higher heat index, increase in cooling degree days
      • Fewer frost days, cold waves, and heating degree days
    2. Hydrologic Cycle
      • Globally averaged water vapor, evaporation and precipitation are projected to increase
      • Increase in cloud cover
      • Increase in precipitation and extreme events
      • Although general drying of mid-continental areas
      • Due to increased temperature and evapotranspiration that is not balanced by increases in precipitation
      • Increase in areas, frequency and intensity of tropical cyclone formation
      • Increase in variability and extreme events
    3. Snow and Ice
      • Decrease snow and ice distribution in Northern Hemisphere
        • Decrease in winter snow, decrease snow storage
          • Permafrost thawing
          • Later freezing and earlier breakup of ice on rivers and lakes
        • Decrease in Greenland glacier and valley glacier extent
          • Adds to sea level increase
        • Decrease in thickness and extent of sea ice
      • Increase in snowfall in some Antarctic regions
        • Gain in Antarctic ice mass
      • West Antarctic Ice Sheet (WAIS)
        • Possible destabilization - but not in the 21st century
    4. Ocean Circulation
      • Increased surface water temperature
      • Decrease in thermohaline circulation
        • Due to increase stratification in Arctic-North Atlantic
          • Warming of surface waters
          • More freshwater runoff into Arctic
        • Reduction in warming of North Atlantic/Europe region
        • Decrease deep-water oxygen levels
        • Reduce oceanic carbon uptake
      • Increase in El Nino-like change in mean state of tropical Pacific sea surface temperatures
    5. Sea Level Rise
      • Increase in global average sea level from 1990-2100 of 0.11 to 0.77m
        • Thermal expansion = 0.11-0.43m
        • Melting valley glaciers = .01-.23m
        • Greenland = -.02-0.09m (total volume = 7m)
        • Antarctica = -0.17-0.02 (total volume = 63m)
          • WAIS = 3m
      • The rate of rise will increase by 2-4 times the rate of the 20th century
  2. Cross-cutting Impacts
    1. Hydrology and Water Resources
      • Widespread increase in risk of flooding for many human settlements (tens of millions) due to increased heavy pptn events and sea-level rise
      • Decrease in water availability in many water-scarce regions, particularly in the tropics
        • 1.7 billion people, 1/3 of the world’s population, presently live in countries that are water-stressed (defined as using more than 20% of their renewable water supply)
        • This number may increase to 5 billion by 2025 — depending on rate of population growth
      • Increased water availability in some water-scarce regions, for examples, parts of southeast Asia
      • More winter pptn may fall as rain, resulting in decreased water storage in snow
    2. Agriculture and Food Security
      • Increased CO2 can stimulate crop production and yield vs. increased heat and water stress
      • General decline in potential crop yields in most tropical and sub-tropical regions
        • These crops are near maximum temp tolerance
      • Increase in potential crop yields in some regions at mid-latitudes for increases in temperature of a few °C
      • General reduction in potential crop yields in most mid-latitude regions for annual average temperature increase of more than a few °C
      • Poleward shift in crops and crop pests
    3. Terrestrial and Freshwater Ecosystems
      • Poleward and altitudinal shifts of plant and animal ranges
        • Holdridge life zones
          • Projected poleward shift of 100miles(160km)/°C and altitudinal shift of 100m/°C
        • Regional shifts in species composition
          • But temperate forests can only migrate ca. 62miles(100km)/century
        • Fragmentation won’t allow intact migration
      • Potential increase in timber supply from appropriately managed forests
    4. Coastal Zones and Marine Ecosystems
      • Increased water temperatures
        • Coral bleaching
        • Migration of species poleward
        • Disruption of upwelling zones
        • Displacement of fisheries
      • Increased coastal flooding
      • Loss of wetlands and mangroves
        • 1mm/year migration vs. minimum sea level rise of 1mm/yr, maximum of 7mm/yr
      • Seawater intrusion into freshwater resources
      • Increased extent and severity of storm impacts, e.g storm-surge floods and shore erosion
      • High latitudes: higher wave energies and thermal erosion
    5. Human Health
      • Increase in number of people exposed to vector-borne (e.g. malaria) and water-borne (e.g. cholera)
        • Malaria and dengue currently impinge on 40-50% of the world population
      • Increase in heat stress mortality
        • Increase in heat waves, humidity and urban air pollution
      • Reduction in winter mortality in mid- and high-latitudes
      • Storm flooding causing increased risk of drowning, diarrheaol, respiratory, malnutrition
    6. Human Settlements, Energy and Industry
      • Increased risk of flooding and landslides
        • Caused by increases in rainfall intensity and coastal sea level rise
      • Increased demand for space cooling
      • Decreased demand for space heating
      • Permafrost thawing undermining structural stability
    7. Other Concerns
      • Impacts of future changes in climate extremes are expected to fall disproportionately on the poor
      • Catastrophic Possibilities
        • Shutdown of thermohaline circulation
        • West Antarctic Ice Sheet collapse
        • CO2 and CH4 release from thawing permafrost and coastal hydrates leading to runaway greenhouse effect
  3. IPCC "Research required to improve ability to detect, attribute and understand climate change, to reduce uncertainties, and to project future climate changes"
    1. Observations and reconstructions
      • Reverse decline in observational network
      • Implement strategy for global observations
      • Enhance past climate reconstructions
      • Observe spatial distribution of GHGs
    2. Modeling and process studies
      • Radiative forcing mechanisms and factors
      • Physical and biogeochemical processes and feedbacks
      • Quantify uncertainties in model projections
      • Improve model simulation of climate variability, regional climate, and extreme events
      • Link physical and biogeochemical models and improve coupling with description of human activities

By Stephanie Pfirman.
Last updated 4/16/03 by Sidney Hemming.
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