I = PAT that human population may stabilize at around 11.2 billion in 2100, the I=PAT equation will continue to be relevant for the increasing human impact on the environment in the short to mid-term future. Increased population increases humans' environmental impact in many ways, which include but are not limited to: 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. While GDP per capita measures
Per capita Per capita Per capita is a Latin prepositional phrase: "per" (preposition, taking the accusative case, meaning "by means of") and "capita" (accusative plural of the noun "caput", "head"). The phrase thus means "by heads" or "for each head", i.e., per individual/person. The term is used in a wide variety of social sciences and statistical research contexts, including government statistics, economic indicators, and built environment studies. It is commonly and usually used in the field of statistics in place of saying "per person" (although "per caput" is the Latin for "per head"). It is also used in wills to indicate that