What Is IPAT? - Factors of the Human Impact on the Environment Video

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  • 0:05 What Is IPAT?
  • 2:49 P=Population
  • 3:54 A=Affluence
  • 5:01 T=Technology
  • 6:07 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy


What do the letters IPAT have to do with the environment? Learn how this four-letter equation helps explain the environmental impact of different variables, including population, affluence, and technology.

What Is IPAT?

The world population is growing at a fast pace. Today, you are one of more than seven billion people walking around planet Earth. This number is somewhat mind-blowing when you consider that the total population of the world was less than two billion in the year 1900. That was only a little over 100 years ago.

This population explosion has left many environmental scientists wondering whether there will be enough natural resources on Earth to support so many people. After all, it is pretty easy to imagine that the more people there are, the higher the demand will be for food, water and energy.

However, population is not the only thing that impacts the environment and the availability of resources. Scientists recognize that other variables, such as the consumption habits of individuals within the growing population, as well as the types of technology they use, also factor into the overall health of the environment. In this lesson, you will learn a simple equation that is used to help understand the different factors that impact the environment.

IPAT, which is sometimes written as I = PAT or I = P x A x T, is an equation that expresses the idea that environmental impact (I) is the product of three factors: population (P), affluence (A) and technology (T). This equation was first proposed by two scientists named Ehrlich and Holdren in the early 1970s as a way to calculate the impact of humans on the environment.

While this equation seems like an oversimplification of the many problems our environment faces, it is a good starting point to help understand the effects of economic prosperity and technological advancements on the environment. For example, if person A lives in a village in a third world country where there is no electricity or automobiles, his ecological footprint, which is the measure of the demand for resources required to support a lifestyle, will be lower than person B who lives in a suburban neighborhood of the United States, who drives to and from work every day in an SUV and relies on electricity for everything from cooking his dinner to air conditioning his home. Let's take a closer look at each of the variables of the IPAT equation.

P = Population

When considering the equation IPAT, P = population, or the total number of people. As mentioned earlier, the world population has exploded since the start of the 20th century. However, according to reports from the United Nations, the population is expected to peak at about 9.2 billion later in the 21st century.

Even with a slowdown in growth, population is an important factor in the IPAT equation. To support more people, it will be necessary to expand living areas, which could result in the clearing of more land for housing. At the same time, there will be a growing need for resources, such as water, food and fuel. Providing the basic needs of the growing population will result in the depletion of natural resources and an increase in greenhouse gas emissions that are detrimental to the environment. In other words, as the population increases, so does the environmental impact.

A = Affluence

A = affluence in the IPAT equation. While you might consider someone who is affluent as having an abundance of wealth, when we consider affluence in the IPAT equation, we are really using it to represent the average consumption rate of individuals within the population. As with population, we see that as the affluence, or consumption, of each individual increases, so does the impact on the environment.

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