The Earth currently has a human population of over seven billion people. This large population is causing or exacerbating many of the issues that humanity and all life on Earth face, issues such as pollution, biodiversity loss, insecurity of food supply, lack of living space, overloaded infrastructure, crowded public facilities, disease transmission, and threatened peace and security. 

None of these problems will be easier to resolve with even more people, and all would be easier to resolve with less, and yet our population continues to grow.  Our global population is expected to peak at 9.7 billion in 2064, and to fall back to 8.8 billion by the year 2100: or perhaps to peak at around 11 billion by the year 2100.  These predictions are necessarily imprecise and are the mid-figures of a wide range of possibilities, so the size of the human population on Earth could come to be much greater. 

To understand why such a large and growing population is a problem we need to understand how we are causing the issues that we face.

We humans, like all living things, interact with the environment that we live in by collecting from it the resources that we need to live, and ultimately producing waste from those resources.  Because we exist in such large number and in great concentrations, when we take what we need from our environment we do so at an unsustainable rate that threatens to eliminate finite resources, and at a greater rate than renewable resources can renew.  We also produce waste at a greater rate than other life and the environment around us can absorb it. 

Not only do we produce a large amount of waste, much of the waste that we produce in the modern world is long-lasting, polluting, environmentally destructive, and, unlike the waste our ancient ancestors produced, cannot be absorbed by the natural world.  

The size of the human population is undoubtedly a problem for humanity and all other life on the Earth.  However, to look at just the number of people on Earth, now or in the future, oversimplifies the problem.

When we talk about the process of obtaining the things that we need to live we are talking about our economy, and consuming the products of our economy, which is called consumption.  Our economic activity, and therefore consumption, is the immediate cause of the resource use and waste creation that have such negative effects on the environment and on our own lives.    

Because the issues that we face are most directly caused by our economic activity, the damage caused by these issues can be quantified as the size of the economy.  The global economy is already very large, and is structured in such a way that it must always grow larger, so the damage that we do is large and must grow as the economy grows.

While our large and growing human population certainly exacerbates the many serious issues that the Earth, its environments, and humanity face, it is our economic activity that actually causes these issues.

The large human population of Earth is a factor in the amount of the unsustainable economic activity that we generate, but there is another factor: the amount of economic activity that each person generates.  These two factors combined set the size of the global economy, so the size of the global economy is the size of Earth’s population multiplied by the average consumption of those people. 

However, there is a wide disparity in the amount of economic activity that individual people and different societies generate across Earth – richer people and societies generate far more than poorer people and societies, and therefore use far more resources and generate far more waste and pollution.  For example, in two weeks the average person in the United Kingdom generates more carbon dioxide than the average person in a poor African nation does in an entire year. 

This means that the vast number of poor people individually contribute little to the issues that earth faces, and that the individual responsibility for most environmental damage falls to people from the richer nations. 

Because poor people contribute little to the issues that Earth faces, many people argue that Earth’s large and growing human population is not a concern, because most of the increasing population is poor. 

(Earth’s population is growing fastest in poor regions, such as Africa and the Middle East, where the population is expected to grow from 1.63 billion people in 2017 to 4 billion people in 2100.  The populations of the richest regions of Earth are expected to fall, halving in 23 countries and territories by 2100.)

However, this argument is only valid if those people remain poor.  The poor people of Earth have a right to pursue a quality of life equal to that of those in the rich world, and morally the rich people of Earth should both allow them and help them to achieve this.  

Reducing poverty and raising the quality of life for poor people means that, by definition, they will consume more.  Poor people have an equal right to a comfortable existence as other people; however, as they become less poor they will consume more resources and create more waste, increasing the demand on the Earth and its environments.  

We are responsible for protecting the existence of our own species as much as any other species because we are part of life on Earth – we have evolved here with all other life.  This not only gives us the right to be here but also gives us a responsibility to ensure our own continued survival as part of the outcome of the existence of Earth and the universe.

Earth has a large, but limited, capacity to sustainably provide for the material and spiritual needs of humanity.  Humanity must collectively share that capacity – the less of us there are, the more we can each have.  The maximum number of us that Earth can sustainably provide for will be the number at which we each have the bare minimum necessary to survive.  Below that number the less of us there are the more we can each have, and the more comfortably we can live.   

To ensure humanity’s sustained existence on Earth we must reduce and equalise our individual consumption and reduce the human population so that the global economy stabilises and reduces to a size that Earth can support, while maximising humanity’s security and comfort. 

There’s a limit to the size of our economy that Earth can support, and therefore there is a limit to the size of our population.  If we don't stop the growth of our population and our economy we will eventually reach that limit.  When we reach it we will suffer the usual consequences for life that uses up its resources.

So, why does our already excessively large population keeps growing, and why do we let it keep growing when it causes so many problems now, will cause more problems in the future, and there are so many reasons to not let it grow? You can find out why we keep our population growing, here.

These letters from choose the future! discuss similar ideas on population to those on this web page:

Read a letter to Kevin Rudd, former Prime Minister of Australia. 

The letter was written when Mr Rudd was Foreign Minister and appointee to the UN Secretary-General's High-level Panel on Global Sustainability, regarding the potentially contradictory nature of the two stated objectives of the panel, which are to facilitate global sustainability and to tackle poverty.

Read a letter to Professor Kishore Mahbubani, Dean of the Lee Kuan Yew School of Public Policy, National University of Singapore

The letter discusses the professor’s statement about the outcome of reducing poverty in Asia, and the need to equitably share the level of economic activity that can occur sustainably, and reduce the size of the global economy.

This page is linked from:

the causes

real world exponential growth

food and water security 

blog post: comment on population in the SMH

the consequences of easy energy

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