Carrying capacity human appropriation and the ecological footprint
Sponsored Links
This presentation is the property of its rightful owner.
1 / 42

Carrying Capacity, human appropriation and the Ecological Footprint PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

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

Download Presentation

Carrying Capacity, human appropriation and the Ecological Footprint

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Carrying Capacity, human appropriation and the Ecological Footprint

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

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 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

  • 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

  • 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

  • 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 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

  • 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 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 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 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 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 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

  • 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 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%


  • Humans appropriate 30% of accessible RFWS

  • Humans appropriate 23% of all RFWS

  • Total runoff appropriated 54%

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)


  • 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

The Concept

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

4 Steps

Step 1.

  • Consumption of various goods and services

  • Measured in Kg consumed/capita

  • C

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


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


  • 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.


  • Sustainability factor

  • EF/total land area available

  • Should be smaller than 1

Calculation – a closer look

Step 1. Consumption Items

  • Food

  • Housing

  • Transportation

  • Consumer goods

  • Services

Consumption Categories

A closer look – Step 2

  • 8 Main land-use categories

    • Energy

    • Consumed land

    • Currently used land

    • Land of limited availability

Land-use Categories


A closer look: The land-consumption Matrix


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

Regional footprints

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

  • 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

  • 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

  • How much ecologically productive land is needed to sequester all the CO2 emissions released by the average Icelander’s fossil fuel consumption?


    Fossil fuel consumption 160GJ/cap/year

    Productivity of energy land 100 GJ/HA

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 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

  • 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


  • Is static

  • Assumes no changes in productivity

  • Assumes equal productivity everywhere

  • Requires more sectors?

  • Requires more products?

  • Login