Human Environment Interactions--The Lithosphere

I.  Critical Roles of the Lithosphere
   A.  Surface Reflectivitiy/Solar Radiation
   B.  Water Balance
   C.  Temperature and region to a global scale climate
   D.  Methane, Carbon Dioxide, a major Carbon Sink
II.  Major Human Induced Changes
   A.  Tropical Deforestation
       1.  Tropical Forests are important because of biodiveristy
           --total forest cover--30%, tropical forest--6%
       2.  Tropical Forests Processes
           a.  oxygen/carbon balance
           b.  maintains surface air temperature; moisture, reflectivity
           c.  biodiversity
           d.  regulates watershed, and waterflow (turbidity of water effects fish habitats)
       3.  Tropical Forest Degradation
           a.  Africa:>50%
           b.  Asia: ~50%
           c.  Central America: 70%
           d.  South America: 40%
           e.  180,000 square miles lost each year, 1 hectare of rain forest processes 1 ton of carbon dioxide annually
           f.  40-70& of plant and animal shecies are native to tropical forests
       4.  Human Induced Changes and Problems
           a.  Overpopulation
           b.  Agriculture (land is only productive for a couple of years)
           c.  Fuel and Lumber
           d.  Burgers and Steaks--developed countries are big consumers of meat and cows  are raised in Brazil
    B.  Desertification
       1.  Arid and Semi-Arid Regions
       2.  Processes
           a.  when plants are removed, excess water and wind causes erosion pavement
           b.  increased surface water runoff leads to declining subsurface water and increased floods
       3.  Causes:
           a.  human vs. natural
           b.  overgrazing, deforestation, clearing for cultivation
       4.  Scale:
           a.  900 million people are effected, 1.2 million hectares
           b.  severe cases:  Algeria, Ethiopia, Iraq, Jordan, Lebanon, Mali, and Niger
   C.  Soil Erosion
       1.  Top soil and lithosphere (about 1 feet)
       2.  Soil composition and formation:
           a.  soil components: rock, inorganic minerals, organic matter, organisms, air, water
           b.  soil forms as a result of decaying organic matter and decomposing rock
           c.  soil depth increases over time, the world is always generating more topsoil
       3.  Mitigating factors of human-induced erosion:
           a.  rotation of crops
           b.  fallowing
           c.  terracing
       4.  Scale:
           a.  a global issue
           b.  severe cases: Guatemala, El Salvador, Turkey, Haiti, China
III.  Video--Drought in Zimbabwe