Responding to the problem begins with realising too many of us consume too much bad crap

This post is serves as a pivot between the problem and the response.

What has caused emissions to rise? How have we found ourself in this predicament? Why are they still rising?

Put simply:

there are too many of us and we consume too much bad crap

In the 1970s, three scientists—Barry Commoner, Paul R. Ehrlich and John Holdren—wondered what caused environmental problems.

The IPAT equation emerged from their discussion, and it proposes that environmental impact is a product of population, affluence and technology.

In other words, too many of us consume too much bad crap.

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The I in the IPAT equation stands for the impact on the environment, or in this case, emissions. The drivers of this are population and affluence, with technology a mitigating factor that can make the ‘bad crap’ less bad.

there’s too many of us

The P in the IPAT equation represents population. There are almost 8 billion of us on Earth and around 80 million more people are born each year.

Holding everything else constant, an increased population means more land and resources are used, and more greenhouse gases are emitted as a result.

After all, 8 billion people need to be fed, watered, transported and sheltered.

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So what do we do?

This is one approach, but putting the ethics and practicality to one side, who are you going to cull first? Slow drivers? The irritating in-laws? The guy that takes the window seat on a plane and gets up every hour to go to the bathroom?

In its medium growth scenario, the United Nations projects that population will increase and stabilise at around 11 billion by around 2100.

So how do we avoid the high and medium growth scenarios and move towards low growth? The clue lies in the next chart:

The chart shows that the population growth rate has been steadily declining over time.

But what drives this downward trend?

Two of the key drivers have been increased access to modern contraception and female education.

Robert Engelman and Robert Kunzig have explored this, noting that around 40 per cent of all pregnancies remain unintended (closer to 50 per cent in the developed world) and that a strategy that elevates women’s status and increases their access to contraception would mean births only result from intended pregnancies.

The strategy would have other benefits—like freeing women to earn money and participate actively in society (as opposed to raising 6, 7, 8, or more children).

There is also a negative correlation between fertility rate and GDP per capita, highlighting how fertility follows levels of development.

This makes sense, right?

If you are an 18-year-old in Western Europe you might be thinking about university, travel, a future career and starting a family.

If you are an 18-year-old in Niger you are less likely to have the privilege of being able to choose between those things.

So sustainable development may offer a path towards a more stable population. But even if population decreased, there’s another key driver…

We consume too much…

The A stands for affluence and represents the average consumption of each person.

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Affluence can be measured through GDP, which at a global scale has been steadily increasing for years.

In fact, the growth in global wealth in the last 30 years has been nothing short of remarkable. By some measures, the amount of global wealth today is five times greater than it was in 1990.

It has lifted billions out of poverty and expanded the global middle class.

And with this increase in wealth comes increased emissions.

This is evident when we plot emissions per capita against GDP per capita. The result being that countries with wealthier citizens tend to emit more per citizen.

The theory here is that a person’s ability to consume grows as they get wealthier, leading to an increase in total environmental impact.

Why is that?

First, the added disposable incomes allows people to consume more of everything, and the production and transportation of these things is generally emissions-intensive.

Second, as people get wealthier, their spending preferences change to more emissions-intensive options.

And it makes sense.

If you are well-off, your household has a car or two in the garage, you consume a diet that emitted a lot of greenhouse gases to produce and transport, you turn on the air-conditioning, and you take international holidays.

Your weekly groceries look very different.

L: Ecuador R: USA. Photograph: Peter Menzel /Barcroft Media

The IPCC’s sixth assessment report explains that households with incomes in the top 10 per cent contribute to around 40 per cent of global emissions, while those in the bottom 50 per cent contribute around 14 per cent.

The IEA has also produced research highlighting how the world’s top 1 per cent of emitters produce over 1000 times more CO2 than the bottom 1 per cent.

Earn more, spend more, emit more.

You might assume that if consumption is leading to more emissions, then the greenhouse gas emissions would be increasing at the same rate, like this:

In reality, emissions per unit of GDP have declined by around 70 per cent compared to 1990 levels.

In other words, economies have grown but have not produced greenhouse gases at an equivalent rate.

The trend for emissions per unit of GDP is consistent across developed and emerging economies.

This might be confusing.

Historically, there have been cases where unchecked development has been closely followed by environmental decay.

The theory goes like this: societies grow, they use the resources around them and pollute their environment until the society collapses, right? This is referenced in Jared Diamond’s ‘Collapse‘ and is an often-cited explanation for the rapid decline of the Mayan civilisation.

Instead, evidence over the last 30 years suggest economies have been able to grow without corresponding increases in emissions. This is in part due to the evolving make-up of national economies and the emergence of technological efficiencies.

Nonetheless, although wealth does not lead to an equivalent increase in emissions, we consume too much per person and overall emissions increase.

So what is too much per person?

The carbon footprint offers one way of measuring this. It is the total greenhouse gases caused by an individual or an entity.

Here is a carbon footprint calculator. It will probably tell you that your footprint is somewhere between 20 and 40 tonnes of CO2 per year.

The global average is closer to 5 tonnes and if everyone lived like those in high-income countries, we might collectively emit 200 billion tonnes of CO2 into the atmosphere every year instead of 35 billion tonnes—and with that, we would have a cooked planet.

Studies will tell you that the best way to reduce your number down from 40 tonnes of CO2 per year is to have fewer children, use your car less, avoid air travel and change your diet.

On top of that, you can decide to change your household energy use, consume different types of goods and services.

But even if you never bought anything, never went anywhere and took animal products out of your diet, the calculator will still show your footprint as being somewhere around 10 tonnes per year.

So what do we do?

The answer is simple. Give away all your possessions, move out of your home, walk to the top of the nearest mountain, find a rock, sit on it and meditate. Once you’ve done that, convince everyone else in the world to do the same…



Ultimately, we live in a world of trade-offs.

Just as it doesn’t make sense to consume nothing, it also doesn’t make sense to have zero pollution. What if you need an ambulance? What if you need to take an emergency flight home? What if you use a laptop for your studies? What if you’re developing technology that sucks emissions out of the air? What if you’re just trying to get to work?

So the answer to the question what is ideal consumption lies somewhere within the quarter-circle in the above image. It exists in a magical point where our needs are met, while minimising the damage to the environment. It is up to each of us to decide where this is.

One way to minimize the overall enrivonmental damage relates making the bad crap less ‘bad’.

bad crap

The term ‘bad crap’ is this context is applied loosely.

An apple is not ‘bad’, a car is not ‘bad’, but the emissions generated in their processing and transportation is problematic.

The T in the equation represents technology, which affects the emissions intensity of consumption. If done well, improvements in efficiency brought on by new technologies can make the ‘bad crap’ we consume less bad, as well as have a mitigating effect on overall emissions.

A key driver of this is technological efficiency and innovation. Firms invest in technologies that allow them to produce the same amount with fewer inputs.

In 1956, American cars had heavy steel frames and inefficient engines resulting in a fuel efficiency of around 15 miles per gallon. Today, a Chevrolet Spark will get you closer to 33 miles per gallon.

Over time, products become better, cheaper, cleaner and more efficient. And while we may be consuming the same, or even more, the ability to consume at a reduce emissions intensity means the emissions per unit of GDP decreases.

Despite this, it is unlikely that society can grow its way to zero emissions. One explanation for this is the rebound effect—where the benefits of efficiency gains are not fully realised. For example, your car becomes cheaper to run per mile, so you drive more.

There are also thermodynamic limits to efficiency improvements. You could never completely reduce material requirements to zero and you couldn’t recycle something forever.

But don’t rule out technology playing a role. When electric cars were first deployed, they used lead-acid batteries, like this.


The cars were heavy, they travelled short range and no one bought them. Then in the late 2000s, electric vehicles switched to lithium ion batteries, like this.

Nokia Battery.jpg

And the efficiency and performance of electric vehicles increased.

Costs also fell. In 2010, the average price of a battery pack for a car was US$1183 per kWh. By 2019 that had fallen to US$156, and is expected to continue to fall.

Low emissions transport is now within reach.

The same trend has been observed for solar cells, wind turbines, in fact—human ingenuity regularly sees technology get better, cheaper and more efficient over time as more funding is invested in research and development.

Our energy predictions are often wrong. Who’s to say what’s on the horizon?

Without these innovations, we would be living in a coal-powered world, driving petroleum vehicles on our way to 11 billion humans.

There are limitations to what technology can do to reduce emissions. Two examples of this are things that involve high heat (e.g. to make cement and steel) and agriculture (e.g. animals digest food and produce methane).

While solutions are in development, they are many years away from being commercially deployable.

A final word

So too many of us consume too much bad crap. Cull the population? Consume less? Invent the technology to make things less bad?

Responses to difficult challenges in the future will need to be smart. They will need to address multiple challenges at once and deliver benefits to different groups of people.

They will need to harness the best parts of an economic system that allocates resources efficiently, encourages innovation and new ideas, promotes fairness and stays within the planetary boundaries.

Some of these ideas will be explored throughout this project.

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