I = P-A-T Model

Global and environmental problems generally are the result of an extremely complex set of interacting causes. A simple model drafted by  Ehrlich & Holdren (1971) illustrates three main type of causes. The size of the human population (P), the level of material affluence of that population (A), and the impact on resources and the environment per unit of affluence (T). The relationship of the three main causes mentioned briefly above can be expressed in an equation that represents the total impact of human activity on the environment (I). Henceforth, I = P x A x T was formulated based on the three variables above.

Overall, a consistent finding is that growing consumption and population are major contributors to the CO2  levels in particular that humans are emitting to the environment. However for this section, we will examine and analysis the factor, “population”.  Population includes demographics such as population size, distribution, and density. Population size is often focused on as the relation between the population size and greenhouse emissions has been demonstrated.

The Human Population (P) has grown exponentially over the last 100 years. With regard to climate change, the effect of population change is much greater in countries with high per-capita emissions. Although the world’s increase in energy demand came from China and India, the United States is still projected to contribute the contribute the most per capita at an astounding rate of two to three more per person than China. However, economists have argued that increases in per capita energy consumption are necessary for economic development in China and India.

With reference to China, they have a large human population and they are increasing their in per capita energy consumption which could result in a dramatic increase in carbon dioxides in the future which could accelerate the rate of Global Warming. This model is just a form of illustration to understand how the impact of the human factors affect the environment per se.



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