Menu Close

Population is only part of the environmental impact equation

Every new person is a new consumer of resources. World Resources

SEVEN BILLION PEOPLE: In the early 1970s, three leading American scientists were locked in a passionate debate about what had made the greatest contribution to humanity’s impact on the environment.

The environmentalist and biologist Barry Commoner argued that advances in technology since World War II had been the most significant.

The entomologist Paul Ehrlich, author of the famous 1968 book The Population Bomb, and the physicist John Holdren, now director of the White House Office of Science and Technology Policy, maintained that humans’ environmental impact was also a function of population and consumption levels.

The debate led to the creation of what is now known as the IPAT formula. This states that humans’ impact on the environment (I) is the product of population (P), affluence (A) and the impact of technology (T): or I = PAT. An increase in just one of these parameters, therefore, increases our environmental impact.

The world’s population is now seven billion, and we are expected to reach nine billion by 2040.

A few nations, such as Japan, Russia and Italy, are experiencing negative population growth. But most countries’ populations are growing, albeit at a reduced rate in recent years.

Growth rates are particularly high in the Middle East, South and South-East Asia, Latin America and Sub-Saharan Africa.

Every new person is a new mouth to feed, a new body to clothe and keep warm, a new consumer of resources and a new producer of waste.

According to Ehrlich and Holdren, population growth has a disproportionately negative effect on the environment. A 1% increase in population doesn’t just mean a 1% increase in environmental impact.

In particular they argued that there was a strong link between population and pollution. Growth in population has a synergistic effect, so that different pollutants can interact and enhance their individual effects on humans and the environment – the whole effect is greater than the sum of the individual effects.

Secondly, they suggested that a threshold for pollution exists; below it, the environment can cope with the pollution, but above it, the system breaks down.

For example, 500 people living around a lake might empty their raw sewage into the lake, and the lake’s natural processes might be able to break down that sewage without harm. But if the population around that lake increases to 700 people and the lake is unable to cope, the environment begins to suffer.

Thirdly, the law of diminishing returns means that as populations increase, we are demanding more and more production from agriculture and forestry. Eventually, we resort to ever higher usage of fertilisers and chemicals in an attempt to wring more from an essentially fixed supply of land.

Whichever way you look at it, they argued that population growth is bad news for the environment.

However, the “A” of the equation – affluence – is also on the increase. To be affluent is to have an abundant supply of wealth, whether in monetary form or in commodities.

In economic terms, it’s an indication of the level of consumption per person, and is often measured as gross domestic product (GDP) per capita. So while China may be experiencing a population growth rate of around 0.6% per year, its GDP per person is increasing at up to 10% per year.

Likewise, India’s population is growing at 1.5% annually, but its GDP per capita is increasing by around 8%. With increased wealth comes increased consumption.

This means that people in China and India are now more than ever able to “keep up with the Joneses”, and they’re wasting no time in doing so.

Accoutrements such as luxury cars, flat-screen televisions and mobile phones – commonplace accessories in a western lifestyle – were once well out of reach for the masses. But as these products become cheaper, and as the average individual wealth of people in these nations increases, they are becoming more attainable.

An increasingly aspirational and rapidly enlarging group of consumers is buying up big-time. The result is greater consumption of resources and more rapid creation of waste. Over recent decades have this has lead to increases in “A” being much greater than increases in “P”.

Finally, we come to the “T” variable of the IPAT equation. This is a measure of the role technology plays in meeting the needs of these increasingly affluent and enlarging populations.

This particular variable is less set in stone than the other two, as it is a measure of the intensity of resource consumption. This means that better, more efficient technologies can lead to fewer resources being consumed for the same economic or societal benefit.

With a low T-value, a more efficient society is able to get more from less, consuming fewer resources to meet the same or increasing needs. It can also generate less waste from the same amount of production.

Of all these variables, T is the one with the most potential to move. Many of our current systems are extremely inefficient. For example, 85% of the energy that your internal combustion engine consumes is not used to move you forward but is rather converted into noise and heat.

This all leads to a critical challenge. As the equation I = PAT states, our impact on the environment is a function of our population, our affluence and the technologies available to us. So, while population increases and affluence are going up, we run the risk of severely impacting our natural resources.

One of the hallmarks of waves of innovation, however, is that technology should never be underestimated; in our book “The Sixth Wave” we argue that the next wave of innovation will be centred on resource efficiency.

In this vision of the world, technology allows us to begin to decouple economic growth from resource consumption, without compromising either population or affluence.

This article is an excerpt of “The Sixth Wave: How to succeed in a resource limited world” by James Bradfield Moody and Bianca Nogrady (Random House, 2010).

Read more:

Sustaining 7 billion: Australia’s part in planning for population growth

Why China’s mega-cities leave their citizens struggling

Seven billion reasons to open our hearts and homes to adoption

Seven billion reasons to be a feminist

Rise of the planet of homosapiens: The death sentence for other life

Want to write?

Write an article and join a growing community of more than 185,600 academics and researchers from 4,983 institutions.

Register now