How is affluence usually measured in the I = PAT equation?

Affluence is usually measured as consumption or economic output per person, such as GDP per head. Higher affluence generally means more goods, energy and travel per person.

What does the technology factor in I = PAT measure?

The technology factor measures the environmental damage caused for each unit of goods or services consumed. Cleaner, more efficient technology gives a lower value of T.

Explain why technology can either increase or decrease environmental impact.

Polluting technologies such as coal-fired power stations can raise the damage per unit consumed. Efficient or renewable technologies such as wind turbines can reduce it.

A country's population rises by 50% and its affluence doubles, while cleaner technology halves the damage per unit consumed. By what factor does its environmental impact change?

The impact rises to 1.5 times its original value. The calculation is 1.5 × 2 × 0.5 = 1.5.

CCEA A-Level Environmental Technology 3930

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Sustainable Development

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Sustainable Development

The I = PAT equation and the role of technology

3 things to know
A2 1

Overview

Ehrlich and Holdren's I = PAT, population, affluence and technology, worked impact calculations, techno-optimism and its critics, the rebound effect and the Jevons paradox, and the limits of the equation.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Debate whether reducing affluence or improving technology is the better way to lower environmental impact.

Key term

Who proposed the I = PAT relationship, and when?

Key term

What does each term in the equation I = PAT represent?

Questions from this subtopic

Each one with the model answer underneath.

1
Who proposed the I = PAT relationship, and when?
Model answer
Paul Ehrlich and John Holdren proposed the I = PAT relationship in the early 1970s. The equation arose from a debate with Barry Commoner about the causes of environmental damage.
2
What does each term in the equation I = PAT represent?
Model answer
Impact (I) equals population (P) multiplied by affluence (A) and technology (T). Affluence means consumption per person, and technology means the damage caused per unit consumed.
3
How is affluence usually measured in the I = PAT equation?
Model answer
Affluence is usually measured as consumption or economic output per person, such as GDP per head. Higher affluence generally means more goods, energy and travel per person.
4
What does the technology factor in I = PAT measure?
Model answer
The technology factor measures the environmental damage caused for each unit of goods or services consumed. Cleaner, more efficient technology gives a lower value of T.
5
Explain why technology can either increase or decrease environmental impact.
Model answer
Polluting technologies such as coal-fired power stations can raise the damage per unit consumed. Efficient or renewable technologies such as wind turbines can reduce it.
6
A country's population rises by 50% and its affluence doubles, while cleaner technology halves the damage per unit consumed. By what factor does its environmental impact change?
Model answer
The impact rises to 1.5 times its original value. The calculation is 1.5 × 2 × 0.5 = 1.5.

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Fossil Fuels

Global Action on Energy Conservation and Climate Change

Macrogeneration

Microgeneration

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