The human presence and impact on this Earth has been changing with our population, technology, and affluence. In order to start understanding how these variables have an impact on Earth (in a general sense) the IPAT equation was created. As is the case for any equation,
I = P x A x T
"I" represents the impacts of a given course of action on the environment
"P" is the relevant human population for the problem at hand
"A" is the level of consumption per person
"T" is impact per unit of consumption. Impact per unit of consumption is a general term for technology, interpreted in its broadest sense as any human-created invention, system, or organization that serves to either worsen or uncouple consumption from impact
The equation is not meant to be mathematically rigorous; rather it provides a way of organizing information for a “first-order” analysis. To achieve meaningful reductions of human impact, there are intense debates on where the focus should lie. Where one group sees expensive remedies with little demonstrable return, another sees opportunities for investment in new technologies, businesses, and employment sectors, with collateral improvements in global and national well-being.