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The ImPACT Identity

Learning actors' leverage for change along the journey to sustainability requires quantifying the component forces of environmental impact and integrating them. Population, income, consumers behavior, and producers efficiency jointly force impact. Here, we renovate the IPAT Identity to identify actors with the forces. Forcing impact Im are:

P for population,

A for income as gross domestic product (GDP) per capita,

C for intensity of use as a good per GDP, and

T for efficiency ratios as impact per good.

In the ImPACT Identity, parents modify P, workers modify A, consumers modify C, and producers modify T. Because annual percentage changes in component forces add to a change in national impact, actors leverage is reflected transparently in consistent units of annual percentage changes that can be compared from force to force. Examples from energy and food, farming and manufacturing, and steel and water show that declining C, called dematerialization, can temper the sustainability challenge of growth (P × A), and that innovation or efficient technology that lowers T can counter rising consumption (P × A × C). Income elasticity can accommodate connections between income and other forces. From rates of change of forces, the identity can forecast impacts. Alternatively, by identifying the necessary change in forces to cause a projected impact, ImPACT can assay the likelihood and practicability of environmental targets and timetables. An annual 2-3% progress in consumption and technology over many decades and sectors provides a benchmark for sustainability.

For recent ImPACT Identity news relating to PHE, see:

1 March 2017

The Shrinking Footprint of American Meat” by Iddo Wernick and Jesse Ausubel is published by The Breakthrough Institute.   We estimate that between 1969 and 2014 the amount of cropland used for raising land meat for Americans fell by nearly a third: around 9 million acres, about the size of Maryland.  The data used for the calculation can be found here.

The PHE frequently assesses problems with the ImPACT identity.  Supplements to the original ImPACT paper (2002) have been provided in response to questions on that paper and new work.

Supplement 1: Do consumers' behavior and producers' efficiency move in consistent patterns?

View the PowerPoint presentation.

Supplement 2: Air Travel -- the example of Materialization. View the PowerPoint presentation.

Supplement 3: New ways to visualize the ImPACT identity and its forces. View the PowerPoint presentation.

Supplement 4: The Sustainability Plane -- sustainability as a journey on a plane to richer & cleaner coordinates in a short text and six slides. View the PowerPoint presentation or Word document.

Supplement 5: With a victory over trash, New York City traced an environmental Kuznets Curve on the sustainability plane during the 20th Century. View the article (PDF).

Supplement 6: DynaCad, a simulator of cadmium flow from zinc processing and cadmium recovery through the manufacturing, use, and exhaustion of products. Download the model (Excel spreadsheet).

About the icon –figure showing three rice plants and the historic progression toward high-yield dwarf varieties

Publications about The ImPACT Identity

1139 Ausubel JH, Wernick IK, Waggoner, PE. Peak Farmland and the Prospect for Land Sparing (PDF). Population and Development Review 38(Supplement): 217-238, 2012 Peak Farmland and the Prospect for Land Sparing,

1129 A Rautiainen, I Wernick, PE Waggoner, JH Ausubel, PE Kauppi. A National and International Analysis of Changing Forest Density [external link]. PLoS ONE 6(5): 2011 A National and International Analysis of Changing Forest Density, timber volume, forest density, carbon sequestration

0107 JH Ausubel, PE Waggoner. Dematerialization: variety, caution, and persistence [external link]. Proc Natl Acad Sci U S A 105(35): 12774-12779, 2008 10.1073/pnas.0806099105 DDematerialization: variety, caution, and persistence, Dematerialization, Consumption, carbon, cropland, energy, fertilizer, impact

0104 JH Ausubel, PE Waggoner. Quandaries of forest area, volume, biomass, and carbon explored with the forest identity [external link]. Connecticut Agricultural Experiment Station Bulletin 1011: 1-3, 2007 Quandaries of forest area, volume, biomass, and carbon explored with the forest identity, Forest, tree volume, carbon sequestration, allometry

0099 JH Ausubel, IK Wernick, AM Barret, PE Waggoner. Industrial ecology for leverage to let loose less cadmium  (PDF). Prog Ind Ecol 3(6): 522-537, 2006 Industrial ecology for leverage to let loose less cadmium , Industrial ecology, cd, cadmium, zn, zinc, recycling, materials flow analysis, ImPACT identity

0091 PE Waggoner, JH Ausubel. A framework for sustainability science: a renovated IPAT identity [external link]. Proc Natl Acad Sci U S A 99(12): 7860-7865, 2002 A framework for sustainability science: a renovated IPAT identity, environmental Impact identity, population, affluence, impact identity

0056 IK Wernick, PE Waggoner, JH Ausubel. Searching for leverage to conserve forests: The industrial ecology of wood products in the U.S.. J Ind Ecol 1(3): 125-145, 1997 Searching for leverage to conserve forests: The industrial ecology of wood products in the U.S., Forests, land use, agriculture, wood products, forestry