carrying capacity human appropriation and the ecological footprint
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Carrying Capacity, human appropriation and the Ecological Footprint. Readings. Vitousek 1986, Postel et al, 1996, rprogress.org optional – Daly et al 1992. Carrying Capacity. Upper limit to the ultimate size - carrying capacity (CC): Logistic or density dependent growth Growth determined by:

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carrying capacity human appropriation and the ecological footprint

Carrying Capacity, human appropriation and the Ecological Footprint

Readings. Vitousek 1986, Postel et al, 1996, rprogress.org optional – Daly et al 1992

carrying capacity
Carrying Capacity
  • Upper limit to the ultimate size - carrying capacity (CC):
  • Logistic or density dependent growth

Growth determined by:

Pt = Pt-1 + r* Pt-1 * (CC - Pt-1)/CC

Can we measure cc?

Does it make sense to measure CC?

carrying capacity1
Carrying Capacity
  • Definition: The maximum population of a species an area can support without reducing its ability to support the same species in the future
  • Function both of the area and the organism (ex. Ceteris paribus Larger area higher cc)
different cc for different species
Different CC for different species
  • Human carrying capacity
    • Complicated by individual differences in the amount and quality of resources consumed and the evolution in the types and quantity of the stuff we consume.
    • Issues?
    • Is it static?
categories of cc
Categories of CC
  • Biophysical carrying capacity
    • Maximum population size that could be sustained biophysically given certain technological capabilities
  • Social carrying capacity
    • maximum population that can be sustained under varying social systems.
    • Smaller than biophysical cc
estimating cc
Estimating CC
  • Total area times productivity/ccal needed to survive (e.g.)
  • Total area times productivity of that area – divided by total kcal required to survive.
    • How many calories people need to survive.
    • 5.9 billion people.
  • Useful? Realistic? Are we already appropriating too much?
a closer look 1 human appropriation of the products of photosynthesis
A closer look 1Human appropriation of the products of photosynthesis
  • Vitousek et al. 1986
  • Examined the impact on the biosphere by calculating the NPP (Net primary production) that humans have appropriated
  • Seminal study
human appropriation of the products of photosynthesis
Human appropriation of the products of photosynthesis
  • NPP: is the amount of energy left after subtracting the respiration of primary producers from the total amount of energy that is fixed biologically through photosynthesis
  • Total food resource on the earth
human appropriation of the products of photosynthesis1
Human appropriation of the Products of Photosynthesis
  • Three calculations:
  • Low estimate: The NPP used directly for food, fuel, timber or fibers
  • Intermediate estimate: The productivity of land that is entirely devoted to human activities
  • High estimate: The above and productive capacity lost due to land conversion
human appropriation of the products of photosynthesis2
Human appropriation of the Products of Photosynthesis
  • Low Calculation:
    • Consumption or production of grain
    • Consumption by life-stock
    • Forests
    • Aquatic ecosystems

=> 3% of all NPP

human appropriation of the products of photosynthesis3
Human appropriation of the Products of Photosynthesis
  • Intermediate calculation
    • Includes what is co-opted by humans
      • Cropland
      • Pasture land
      • Forests use and conversion
      • Others such as lawns, golf courses and gardens

=>19.9% of total NPP.

human appropriation of the products of photosynthesis4
Human appropriation of the Products of Photosynthesis
  • High calculation
    • Includes losses in productivity
      • Replacement of natural ecosystems with agricultural systems
      • Forest conversion to pasture
      • Desertification
      • Areas occupied by humans

=>40% of terrestrial NPP, 25% of global NPP

a closer look 2 human appropriation of the products of freshwater
A closer look 2Human Appropriation of the products of freshwater
  • Objective:
  • Assess how much of the Earth’s renewable freshwater is realistically accessible to humans
  • Assess how much humans use directly
human appropriation of the products of freshwater
Human Appropriation of the Products of Freshwater
  • Terrestrial renewable freshwater = Precipitation = Evapotranspiration + Eventual runoff to the sea
  • Evapotranspiration (EP): Based on how much of NPP we use (use high estimate)

=> We appropriate 26% of all EP

human appropriation of the products of freshwater1
Human Appropriation of the Products of Freshwater
  • Total runoff (40,700 km3/year):
    • Not accessible runoff excluded
    • Accessible (12,500 km3/year)
      • Withdrawals, consumption (we use 36% of all)
      • Instream uses (we use 18% of all)
    • Total appropriated 54%
slide16
Conclusion
  • Humans appropriate 30% of accessible RFWS
  • Humans appropriate 23% of all RFWS
  • Total runoff appropriated 54%
the ecological footprint
The ecological footprint
  • Is a measure of the load imposed by a given population on nature.
  • Represents the land area required to sustain a given level of resource consumption and waste discharge by that population
  • The land area required to provide the energy and material requirements by the economy (measured in ha)
measuring
Measuring
  • The land required to sustain a particular human population - that is the area of land of various classes that is required on a continued basis to:
    • Provide all the energy and material resources consumed
    • Absorb all the wastes that assimilate
core footprint issues
Core footprint issues
  • Current industrial practices are sustainable
  • Include only basic natural services
  • Try not to double count
  • Simplify the ecological productivity values
  • Not really account for marine areas
the calculation
The Calculation

4 Steps

Step 1.

  • Consumption of various goods and services
  • Measured in Kg consumed/capita
  • C
the calculation1
The Calculation
  • Step 2.
  • Assess the productivity of each land category required (given in program)
  • Defined as how much land area is required to produce a particular amount
  • Use global averages
  • Measured in kg/ha
  • P
calculation
Calculation

Step 3.

  • Assess the land mass appropriated per capita for the production of each consumption item.
  • Measured in hectare per capita

=> aa = C/P = (kg/capita)/(kg/ha) = ha/capita

calculation1
Calculation
  • Step 4.
  • Sum over all aa – to get total EF
  • ∑aa, giving EF per capita per population

Then of course you can multiply the total EF per capita by total population to get EF per nation.

calculation2
Calculation
  • Sustainability factor
  • EF/total land area available
  • Should be smaller than 1
calculation a closer look
Calculation – a closer look

Step 1. Consumption Items

  • Food
  • Housing
  • Transportation
  • Consumer goods
  • Services
a closer look step 2
A closer look – Step 2
  • 8 Main land-use categories
    • Energy
    • Consumed land
    • Currently used land
    • Land of limited availability
results in a global context
Results in a global context
  • United States – 9.7 ha/capita
  • Canada – 8.4 ha/capita

- NS - 8.1 ha/capita

- AB - 7.9 ha/capita

  • France – 5.3 ha/capita
  • Japan – 4.8 ha/capita
  • Zimbabwe – 1.3 ha/capita
  • Bangladesh – 0.5 ha/capita

Global Average: 2.3 hectares/capita

some results
Some results
  • North American average 9,7 ha/person
  • Total land required 9,7*6 billion
  • Require 57 billion - only have 13 ha productive (need 4 earths)
  • Average footprint is 2,3 ha/person - need 13,8 billion ha
ef applications
EF Applications
  • Region (country, province, town, university campus)
  • Personal Ecological Footprint (redefining progress, mountain equipment co-op)
  • Competing technologies (fuel cells)
  • Growing Techniques (field tomato vs. hydroponic tomato)
  • Policy decisions (rail vs. road, urban planning decisions)
  • Purchase decisions (cradle to grave)
  • Other (big mac, aquaculture, newspaper)
ef in use
EF in Use
  • Teach concepts of sustainability, environmental issues, responsibility.
  • Benchmark of School Sustainability (define current state, assess progress -- footprint increase? Footprint decrease?)
  • Means of Comparison (between schools, between grades, students vs. teachers)
  • Promote holistic decision making
fun with footprints
Fun with footprints
  • How much ecologically productive land is needed to sequester all the CO2 emissions released by the average Icelander’s fossil fuel consumption?

Assume:

Fossil fuel consumption 160GJ/cap/year

Productivity of energy land 100 GJ/HA

fun with footprints1
Fun with footprints
  • How much area do you need to produce paper for the average Icelander?
  • 113 kg paper/cap/yr
  • Each metric ton requires 1,8 M^3 of wood
  • Wood productivity 2,3 M^3/ha/yr
fun with footprints2
Fun with footprints
  • The ecological footprint of various modes of transportation in Reykjavik
  • Ecological footprint of vegans vs others
  • Ecological footprint of the University
advantages of the concept
Advantages of the concept
  • Is clear and understandable
  • Are we living beyond our means?
  • Can be used in the Local Agenda 21 process
  • Can be used as a benchmarking tool
  • Can be used to public relations, information, motivation or for forming public opinion
  • Can be used comparatively
    • Nations, regions
    • Technologies, behaviors
disavantages
Disavantages
  • Is static
  • Assumes no changes in productivity
  • Assumes equal productivity everywhere
  • Requires more sectors?
  • Requires more products?
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