{"id":33,"date":"2019-01-14T19:17:11","date_gmt":"2019-01-14T19:17:11","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-sustainability-a-comprehensive-foundation\/chapter\/the-ipat-equation\/"},"modified":"2019-01-25T18:22:56","modified_gmt":"2019-01-25T18:22:56","slug":"the-ipat-equation","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-sustainability-a-comprehensive-foundation\/chapter\/the-ipat-equation\/","title":{"raw":"The IPAT Equation","rendered":"The IPAT Equation"},"content":{"raw":"

As attractive as the concept of sustainability may be as a means of framing our thoughts and goals, its definition is rather broad and difficult to work with when confronted with choices among specific courses of action. The Chapter Problem-Solving, Metrics, and Tools for Sustainability<\/strong> is devoted to various ways of measuring progress toward achieving sustainable goals, but here we introduce one general way to begin to apply sustainability concepts: the IPAT equation.<\/p>\r\n

As is the case for any equation, IPAT expresses a balance among interacting factors. It can be stated as<\/p>\r\n\r\n

[latex]I=P\\times A\\times T[\/latex]<\/div>\r\n

where I<\/em> represents the impacts of a given course of action on the environment, P<\/em> is the relevant human population for the problem at hand, A<\/em> is the level of consumption per person, and T<\/em> 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.<\/p>\r\n

Suppose we wish to project future needs for maintaining global environmental quality at present day levels for the mid-twenty-first century. For this we need to have some projection of human population (P<\/em>) and an idea of rates of growth in consumption (A<\/em>).<\/p>\r\n\r\n

<\/figcaption>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"412\"]\"graph World Population Growth<\/strong> Source: U.S. Census Bureau, International Data Base, December 2010 Update<\/a>[\/caption]<\/figure>\r\n

Figure World Population Growth<\/strong><\/a> suggests that global population in 2050 will grow from the current 6.8 billion to about 9.2 billion, an increase of 35%. Global GDP (Gross Domestic Product, one measure of consumption) varies from year to year but, using Figure Worldwide Growth of Gross Domestic Product<\/strong><\/a> as a guide, an annual growth rate of about 3.5% seems historically accurate (growth at 3.5%, when compounded for forty years, means that the global economy will be four times as large at mid-century as today).<\/p>\r\n\r\n

<\/figcaption>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"649\"]\"graph Worldwide Growth of Gross Domestic Product<\/strong> Source: CIA World Factbook, Graph from IndexMundi <\/a>[\/caption]<\/figure>\r\n

Thus if we wish to maintain environmental impacts (I) at their current levels (i.e. I2050<\/sub> = I2010<\/sub>), then<\/p>\r\n\r\n

[latex]{P}_{\\text{2010}}\\times {A}_{\\text{2010}}\\times {T}_{\\text{2010}}={P}_{\\text{2050}}\\times {A}_{\\text{2050}}\\times {T}_{\\text{2050}}[\/latex]<\/div>\r\n

or<\/p>\r\n\r\n

[latex]\\frac{{T}_{\\text{2050}}}{{T}_{\\text{2010}}}=\\left[\\frac{{P}_{\\text{2010}}}{{P}_{\\text{2050}}}\\right]\\times \\left[\\frac{{A}_{\\text{2010}}}{{A}_{\\text{2050}}}\\right]=\\left[\\frac{1}{1\\text{.}\\text{35}}\\right]\\times \\left[\\frac{1}{4}\\right]=\\left[\\frac{1}{5\\text{.}4}\\right][\/latex]<\/div>\r\n

This means that just to maintain current environmental quality in the face of growing population and levels of affluence, our technological decoupling will need to reduce impacts by about a factor of five. So, for instance, many recently adopted \"climate action plans\" for local regions and municipalities, such as the Chicago Climate Action Plan<\/a>, typically call for a reduction in greenhouse gas emissions (admittedly just one impact measure) of eighty percent by mid-century. The means to achieve such reductions, or even whether or not they are necessary, are matters of intense debate; 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.<\/p>","rendered":"

As attractive as the concept of sustainability may be as a means of framing our thoughts and goals, its definition is rather broad and difficult to work with when confronted with choices among specific courses of action. The Chapter Problem-Solving, Metrics, and Tools for Sustainability<\/strong> is devoted to various ways of measuring progress toward achieving sustainable goals, but here we introduce one general way to begin to apply sustainability concepts: the IPAT equation.<\/p>\n

As is the case for any equation, IPAT expresses a balance among interacting factors. It can be stated as<\/p>\n

[latex]I=P\\times A\\times T[\/latex]<\/div>\n

where I<\/em> represents the impacts of a given course of action on the environment, P<\/em> is the relevant human population for the problem at hand, A<\/em> is the level of consumption per person, and T<\/em> 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.<\/p>\n

Suppose we wish to project future needs for maintaining global environmental quality at present day levels for the mid-twenty-first century. For this we need to have some projection of human population (P<\/em>) and an idea of rates of growth in consumption (A<\/em>).<\/p>\n

<\/figcaption>
\"graph<\/p>\n

World Population Growth<\/strong> Source: U.S. Census Bureau, International Data Base, December 2010 Update<\/a><\/p>\n<\/div>\n<\/figure>\n

Figure World Population Growth<\/strong><\/a> suggests that global population in 2050 will grow from the current 6.8 billion to about 9.2 billion, an increase of 35%. Global GDP (Gross Domestic Product, one measure of consumption) varies from year to year but, using Figure Worldwide Growth of Gross Domestic Product<\/strong><\/a> as a guide, an annual growth rate of about 3.5% seems historically accurate (growth at 3.5%, when compounded for forty years, means that the global economy will be four times as large at mid-century as today).<\/p>\n

<\/figcaption>
\"graph<\/p>\n

Worldwide Growth of Gross Domestic Product<\/strong> Source: CIA World Factbook, Graph from IndexMundi <\/a><\/p>\n<\/div>\n<\/figure>\n

Thus if we wish to maintain environmental impacts (I) at their current levels (i.e. I2050<\/sub> = I2010<\/sub>), then<\/p>\n

[latex]{P}_{\\text{2010}}\\times {A}_{\\text{2010}}\\times {T}_{\\text{2010}}={P}_{\\text{2050}}\\times {A}_{\\text{2050}}\\times {T}_{\\text{2050}}[\/latex]<\/div>\n

or<\/p>\n

[latex]\\frac{{T}_{\\text{2050}}}{{T}_{\\text{2010}}}=\\left[\\frac{{P}_{\\text{2010}}}{{P}_{\\text{2050}}}\\right]\\times \\left[\\frac{{A}_{\\text{2010}}}{{A}_{\\text{2050}}}\\right]=\\left[\\frac{1}{1\\text{.}\\text{35}}\\right]\\times \\left[\\frac{1}{4}\\right]=\\left[\\frac{1}{5\\text{.}4}\\right][\/latex]<\/div>\n

This means that just to maintain current environmental quality in the face of growing population and levels of affluence, our technological decoupling will need to reduce impacts by about a factor of five. So, for instance, many recently adopted “climate action plans” for local regions and municipalities, such as the Chicago Climate Action Plan<\/a>, typically call for a reduction in greenhouse gas emissions (admittedly just one impact measure) of eighty percent by mid-century. The means to achieve such reductions, or even whether or not they are necessary, are matters of intense debate; 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.<\/p>\n\n\t\t\t

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Candela Citations<\/h3>\n\t\t\t\t\t
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