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Ecological FootprintsMaterial (Resource) Flow Analysis

Scott Matthews12-712 / 19-622

Lecture 7

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Administrative Issues

• HW 2 Solutions, Returned

• HW 3 Due Today

• Thoughts on Due Dates for Final/etc?

• Project Report Updates Due

• Short class today

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Timeline Planning

Sun Mon Tues Wed Thurs Fri Sat

10/13 – Last Class (projects Due)

Take-home final due?

Take-home final due?

Take-home final due?

Take-home final due?

Take-home final due?

10/20 Mini 2 Starts

10/22 Mini Grades Due

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Main question is when to make projects, take home finals dueNote Friday 10/17 is “midsemester break”

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Cities

• More than 50% of population in cities, growing

• Why the crunch from rural to urban?– Ability to meet needs locally versus needing to depend on

transport/etc for fulfillment

– Where does food come from (1000s of miles)

• Not just a developed world issue – developing world shifting quickly

• Interdependence, also globalization of production./cost minimization/etc– New supply chains, including refrigeration

• Tradeoffs between simplicity of meeting needs locally versus potential scale of distant production. Which weighs more?

• Urbanization tends to magnify the imapcts because of the large scale (non-linear)

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Summary: An Ecological Footprint

• Process– Factors in a number of categories

of consumption and use– Converts these inputs to a

quantity of land

• One specific model used– Redefining Progress– Based on research of

Wackernagel and Rees

http://www.absentofi.org

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Ecological Footprintfrom www.footprintnetwork.org

(specifically the data/methods page)

• An indicator that takes a variety of inputs and converts into equivalent land use– e.g., carbon emissions need biocapacity to be mitigated– Food/etc – land needed to farm it

• Relevant benchmark “number of earths” (similar to carrying capacity)

• “Earths” basis defined by biocapacity• See the reports and spreadsheets there if you have

not already done so!

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Biocapacity vs. Ecological Footprint

• Units: global hectares (equivalent land measure)

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2003 difference: about 25%. Meaning?

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Delving Deeper into EF Approach

• Majority of resources we use can be approximated by biocapacity (biologically productive area) needed to sustain it– Those that cannot be estimated are excluded

(examples/effect)?– Describe the kinds of data needed for the biocapacity and EF

side of such a comparison

• Carbon land: first considers ocean uptake, everything else forest sequestration

• Used to compare national resource consumption with bioproductive land available– 200 resource categories

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• In last 40 years,

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Relevant Country Measures

• Macro-level (total global hectares) and ratios for each country, and per-capita

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Population

Ecol. Footprint (ha/person

)

Bio-capacity (ha/person)

Deficit (%)

World 6,301.5 2.2 1.8 +26%High income countries 955.6 6.4 3.3 +95%Middle income countries 3,011.7 1.9 2.1 -9%Low income countries5 2,303.1 0.8 0.7 +13%

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Highest/Lowest

• Where is US?• Top Five “Worst” Top Five “Best”

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Country Factor

Iraq 25.33

Kuwait 21.77United Arab Emirates 13.13

Israel 11.11

Lebanon 9.71

Country Factor

Brazil -0.78

Zambia -0.82

Bolivia -0.91

Congo -0.92

Gabon -0.93

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Lower Levels

• Ecological Footprints at local levels “spatial ft-prints”• Same data/etc.• Alternate visualization• e.g., urban funnels (Grimm 2001)

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Traditional Ecological Footprints

for Phoenix, AZ

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Assimilated CarbonWaterFood

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Increasing

Distribution of Agricultural Food Production

Data: US Department of Agriculture 1998

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Distribution of Renewable Water Availability(Precipitation - Evapotranspiration)

Precipitation: Daly and Taylor 1994; ET (Actual): Ahn and Tateishi 1987

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Distribution of Carbon Assimilation

Data: Century model by VEMAP project

Increasing

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#

Phoenix, AZ

Spatially Explicit Ecological Footprints

for Phoenix, AZWater Food

Note –circles are traditional method of calculating footprint, for each resource

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Central Arizona Project Canal EFs

Domestic water use only

Domestic + agricultural water use

CAP canal watershed

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Water EF for 20 largest US cities

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Water EF with agriculture interaction

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Caveats/Discussion

• EF is just one, albeit highly controversial approach.• However its in the right direction of sustainability

metrics, especially with respect to scientific data/methods and showing results by country/etc.

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