Editing I = PAT (section)

===Affluence===
{{Main|Consumption (economics)}}

[[File:Historic world GDP per capita.svg|thumb|right|upright=1.5|World GDP per capita (in 1990 [[International dollar|Geary–Khamis dollars]])]]

The variable '''A''' in the I=PAT equation stands for [[affluence]]. It represents the average consumption of each person in the population. As the consumption of each person increases, the total environmental impact increases as well. A common proxy for measuring consumption is through [[GDP per capita]] or [[List of countries by GNI (nominal) per capita|GNI per capita]]. While GDP per capita measures production, it is often assumed that consumption increases when production increases. GDP per capita has been rising steadily over the last few centuries and is driving up human impact in the I=PAT equation.

====Environmental impacts of affluence====
<!-- Not a great example - needs fleshing out; number of automobiles per capita would be a better example, as it changes, ... -->

Increased consumption significantly increases human environmental impact. This is because each product consumed has wide-ranging effects on the environment. For example, the construction of a car has the following environmental impacts:

* 605,664 gallons of water for parts and tires;<ref name ="Phillis">{{Cite journal | last1 = Andriantiatsaholiniaina | first1 = L. A. | last2 = Kouikoglou | first2 = V. S. | last3 = Phillis | first3 = Y. A. | doi = 10.1016/j.ecolecon.2003.08.009 | title = Evaluating strategies for sustainable development: Fuzzy logic reasoning and sensitivity analysis |journal = [[Ecological Economics (journal)|Ecological Economics]]| volume = 48 | issue = 2 | page = 149 | year = 2004 | bibcode = 2004EcoEc..48..149A }}</ref>
* 682&nbsp;lbs. of pollution at a mine for the [[lead battery]];<ref name ="Phillis" />
* 2178&nbsp;lbs. of discharge into water supply for the 22&nbsp;lbs. of copper contained in the car.<ref name ="Phillis" />

The more cars per capita, the greater the impact.
Ecological impacts of each product are far-reaching; increases in consumption quickly result in large impacts on the environment through direct and indirect sources.