Lecture 7

Brief outline of the day:

• comments on mini-quiz (C,N,P)
• Element biogeochemical cycles
• ecological and anthropological processes
• energy steady state
  • potential pos and neg feedbacks
• thresholds

Lecture Notes:

Results from mini-quiz

Next mini-quiz

Hydrologic cycle

Biogeochemical cycles

http://www.eoearth.org/article/Global_material_cycles

http://www.eoearth.org/article/Nitrogen_cycle

http://www.eoearth.org/article/Carbon_cycle

http://en.wikipedia.org/wiki/Biogeochemical_cycle

http://en.wikipedia.org/wiki/Carbon_cycle

http://en.wikipedia.org/wiki/Phosphorus_cycle

http://en.wikipedia.org/wiki/Nitrogen_cycle

Key ecological and anthropogenic processes

coupled processes - change one place

• carbon
  • fossil fuel consumption
• nitrogen fertilizer
  • Haber Bosch process
    • 40 % of nitrogen for crops
    • 1-2 % of total industrial energy use
  • proportion anthropogenic
  • more corn production --> dead zone in Gul
• phosphorus
  • mining and distribution of fertilizer

following these three

• "mixed unit" problem
• different time scales in natural cycles
• overwhelming power in anthropogenic impact

energy steady state for the planet

• input = output
• systems models

steady-state-feedback.html

• thresholds for rapid change
• fast and slow feedbacks
• tipping points
• 350ppm
  • James Hansen - Bill McKibben

• doubling of CO2 leads to 3 deg or 6 deg change in steady state temp
• slow feedbacks such as shrinking ice sheets, more forests poleward, methane
• even with immediate reduction, some change in temperature will still happen