planetary boundaries

planetary boundaries

1. purpose

   • to maintain human impacts to remain in Earth's holocene state
     • prevent abrupt shifts to sensitive subsystems
       • monsoon systems
     • changes in one boundary affect another
   • "define a safe operating space for humanity " with respect to the Earth systems
   • A (normative) science and policy framework

2. anthropocene

   • 250 years ago
   • industrial revolution
     • 1750s steadily increasing impacts
       • widespread exploitation of fossil fuels
       • accelerating beginning in 1950s
       • impacts uneven across groups
         • 1 Euro american consumers 25 x the resources that 1 average citizen from a developing country
     • industrialized forms of agriculture

3. holocene

   • 10,000 yrs of stability
     • human civilizations developed
       • accessing food
       • controlling and manipulating fire
       • hunting
       • (8000) clearing forests and conversion of land to cropping
       • irrigated rice cultivation (5000)
     • regular temperatures
     • freshwater availability
     • biogeochemical flows

4. 9 thresholds that if crossed will generate unacceptable environmental change

   • 1. climate change rate
     • 350 parts per million by volume
       • 387
         • <+2 C
         • loss of major ice sheets
         • accelerated sea level rise
         • abrupt shifts in forest systems
           • thinning out
           • shift with ecosystems
       • <+2 C
     • climate change
   • 2. rate of biodiversity loss
     • 10 extinction rate(# of species per million species per year)
       • 10
         • >100
       • conversion to crop lands
       • conversion to urban development
       • natural resource use
   • 3. nitrogen and phosphorous cycles
     • 35 millions of tonnes per year in nitrogen
       • 121
   • 4. stratospheric ozone depletion
   • 5. ocean acidification
   • 6. global freshwater use
   • 7. land use
   • 8. chemical pollution
   • 9. atmospheric aerosol loading
   • 1. identify earth system processes
   • 2. identify thresholds for each process
   • 3. Estimate the "distance" of each control variable from a proposed safe boundary
   • Avoidance
     • reduce consumption

5. 1. Global scale impacts

6. 2. Long-term consequences

7. 3. Complex, interdependent linkages and feedbacks