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The Numbers Game: Population Growth and its Environmental Impact

Updated: Jul 2, 2023

The world population is growing faster than at any other point in human history. But how did this happen and what does it mean for the future of the planet?


Scientists currently estimate that modern human beings (Homo sapiens) first evolved 200,000 years ago: only 0.004% of the Earth’s history. Since then, the global human population has grown steadily over thousands of years, but in recent decades there has been a notable boom. In the 20th century alone the population jumped from 1.5 to 6.1 billion and is predicted to continue to rise.

So why has this happened? Who cares if there are a few extra people around? And why should it matter to us?

“Between 2015 and 2050 world population is projected to increase by nearly 2.5 billion, rising from 7.3 billion to an estimated 9.8 billion. The vast majority of that projected increase—an estimated 97 percent—will occur in the developing world”J. Walker (2016)

And here is that infamous graph everybody seems to be talking about. As you can see, in recent decades there has been an exponential explosion in our population. (If you want to procrastinate, check out this cool website to see the current changing world population).

The History

So how did we get to where we are now? Demographers have identified 3 stages in time where our population has changed significantly. So buckle up and take a tour back in time.

1. Pre-agricultural Period (roughly 12,000 years ago)

The world population today is 1,860-times the size of what it was 12 millennia ago when the world population was around 4 million, or half of the current population of London. During this period we began to transition from hunting and gathering to settled agriculture (also known as the Neolithic Revolution).


Real photo of a prehistoric tractor.

2. Agricultural Period (10,000 – 1,000 years ago)

Animals became domesticated for farming and crop yields went up with the advancement of irrigation and ploughing techniques (yeah, your ancestors were definitely better at ploughing than you). So with more land and more food, there became more of us. About 6,000 years ago we hit 10 million people, which is about the current population of any British seaside town on a sunny day. But the biggest increase was yet to occur.

3. Industrialization Period (1,000 years ago to present)


As wages and work opportunities were more desirable in the cities, people migrated from rural areas into growing urban areas. Better wages, more food, tapped water, and eventually, medical advances meant people were living for longer. At this time, infant mortality was still high so it was quite normal for 2 parents to have 6 children, and 4 of them not to survive past 5 years.


Reasons to Worry

Overpopulation is an undesirable state where the number of existing human population exceeds the carrying capacity of Earth. Only in recent decades have countries taken big leaps to decrease fertility rates. This obviously benefits families almost immediately, but it means we will still have at least another 70+ decades of rapid growth until these actually take a noticeable effect globally. So what will happen if we become overpopulated?

Depletion of Natural Resources

“If everyone on the planet consumed as much as the average US citizen, four Earths would be needed to sustain them.”

This statement has been going around since 2012 after Tim De Chant published how much land would be required if 7 billion people lived the same lifestyle for a range of different countries. He used data produced by the Global Footprint Network (GFN), which has been trying to measure the impact of humans on the planet since 2003.  “Ecological footprinting” is where researchers look at how much land, sea, and other natural resources are used to produce what people consume.

A global hectare is the unit used to answer the question ‘If there is one planet – how much planet is available per person and how much planet do we use per person?’. Using this unit, it’s clear that today the US doesn’t actually have the biggest ecological footprint. It’s actually the United Arab Emirates, which means if everybody lived the same way we would need over 5 planets!

According to the GFN, the world’s population at 7.3 billion is currently using one-and-a-half Earths. The take-home message from this is that there is an imbalance of resource use and the trend shows that the super rich and developed countries are the ones overusing.

Degradation of Environment

Often when resources are depleted, the environment is degraded too. As the demand for natural resources increases and their availability reduces, the methods in which organisations and governments use to extract them become more damaging. Increased use of explosives to expose rocks and minerals for mining (which are only found deeper in the earth’s crust) can wipe out entire habitats and any animal communities which haven’t already fled. Oil companies drill deeper with the risk of earthquakes and spillages, which puts marine and coastal communities at great risks.

According to Population Connection, population growth since 1950 is the cause of the clearing of 80% of rainforests, the loss of tens of thousands of plant and wildlife species, an increase in greenhouse gas emissions of some 400 percent, and the development or commercialization of as much as half of the Earth’s surface land.

It’s this large-scale land alteration which is one of the greatest impacts of rapid population growth. With agriculture comes soil erosion/degradation, possible overuse of fertilizer and pesticides and leaching which contaminates freshwater. On top of this, the livestock sector accounts for 15% of global emissions, equivalent to exhaust emissions from all the vehicles in the world. Something to think about next time you decide to treat yourself to a Macca’s beef burger.


Conflicts and Wars

With resource scarcity comes conflict. Tensions rise within communities when there may not be enough food and water to go around for everyone. This can escalate to crime and protests as people demand more from their governments. This is particularly evident in rural communities where infrastructure is limited, it can leave people in rural regions feeling like they’ve been abandoned by higher powers.

But this is more than just local level conflict. Resource scarcity can define regions and turn countries against each other. In Pakistan and Bolivia, for example, violent protests have broken out over the distribution of water and in the Middle East, disputes over oil fields in Kuwait, among other issues, led to the first Gulf War. By 2050 global energy use will have doubled, and global water demand will have increased by 55 percent over 2012. It’s abundantly clear that the politics of this century will be shaped by how these conflicts are managed and hopefully resolved.

High Cost of Living

Most residents in MEDCs (that’s More Economically Developed Countries for all you that are reading this instead of studying) can absorb the rising costs of living, considering their wages rise proportionally. However, the record high food prices in recent years are proving an immediate threat to the health, and in some cases, even the lives of those who earn the lowest incomes.


In case you need proof to ask your parents for more money for food.

So why has a trip to the supermarket has suddenly become a luxury expenditure for so many people? Extreme weather events have been put forward as one of the reasons. The devastating heat wave that struck Russia in 2010 damaged the wheat crop enough to cause the Russian government to halt grain exports for the year, and heavy rains in Australia damaged wheat crops so much so that they were downgraded for animal food only.  A sure sign of climate change, these extreme weather events are only going to increase in severity and frequency.


More dead than your future prospects.

So what does this mean in the face of increasing demand as our population increases too? A need for more effective food management strategies and education addressing how important it is that we don’t abuse food resources where they are plentiful. If demand goes down, so should the supply in theory, but only if this is backed by everyone making a conscious effort to reduce food miles and waste.

Not only food, but oil and gas prices are likely to keep increasing. George Friedman, in ‘The Next Decade: Where We’ve Been…and Where We’re Going’, said:

‘Certainly oil production has moved to less and less hospitable areas, such as the deep waters offshore and shale, which require relatively expensive technology. That tells us that even if oil extraction has not reached its peak, all other things being equal, oil prices will continue to rise…the increased energy consumption that we will see over the next decade cannot be fueled by oil, or at least not entirely.’

What We Leave Behind


Plastic is one of the cheapest and most widely used materials. Everything is either made of plastic or is packaged in it. Every week, the US alone discards enough plastic bottles to encircle the Earth 5 times! And unfortunately, it’s so well-designed that it won’t disappear at all. Plastic takes 700 years to degrade – and that’s just ‘photo’-degrade, meaning lots of tiny little toxic pieces are left forever. Yep, there is such a thing as being too good at something.

And if that’s not enough to ruin your morning, we have an area of rubbish in the middle of your bedroom the North Pacific Gyre known as the Great Pacific Garbage Patch, which is currently the size of India, Europe, and Mexico combined.

But what has population growth got to do with all of this waste being produced? Essentially, it’s a mix of the volume of the materials being produced now in our very globalised world, and then how little we recycle once we are done with them. Only 1 to 3% of all plastic waste is recycled. After we use them, we throw them away. Your plastic cutlery, Sainsbury’s meal deal packaging, ASOS delivery parcels, early morning Starbucks cup: this is where it’s going. And just like the numbers on the scale, ignoring it doesn’t make the problem go away.

But is it all doom and gloom?

In Hans Rosling’s ‘Don’t Panic- The Truth About Population’ (worth a watch if you want to procrastinate even more!), he analyses a case study from Bangladesh, a country where the population since the 60’s has tripled from 50 million to 150 million. In 1972, after the first full year of independence, the fertility rate was 7 babies per woman with a life expectancy of fewer than 50 years, and now just 40 years later, this has decreased to 2.2 babies per woman with a life expectancy of 70. This is a remarkable culture shift and is proving hugely popular amongst young families in Bangladesh.


A picture might tell a story but it’s not necessarily a true one

But how did it happen? And can all countries with high fertility and birth rates follow suit?

The answer is simple. In Bangladesh, the government employed women to become family planning officers. Their role was to educate and spread the word that ‘2 children is good, 1 is better’ and in the process, offer advice, support, and contraceptives to other women and families in communities.

The benefits of the scheme are well known: the government pays for girls to stay on in school, so much so that girls in some areas now outnumber boys in classrooms. Industries and the jobs sector are now flourishing with the involvement of women in the workplace. Fundamentally, better child survival rates have underpinned the whole success of the scheme. Previously, 1 in 5 children died before they reached 5 years of age in the last generation in Bangladesh, but now with vaccines, better hygiene, and nutrition, which families can afford with fewer children, the majority are surviving childhood.

This isn’t some kind of weird Bangladesh-specific phenomenon: many countries have made huge cultural leaps in the last few decades, including many typically associated with large families. For example in Brazil, Vietnam, and India, the most common family size is 2 children. Globally, in 1963, the average number of children per woman was 5 (although this number is affected by the developed/developing divide). Today, the average is 2.5 babies per woman. So our belief that every developing country has a high birth rate and a huge population says more about our attitudes than reality. The fact is that these countries have made the largest efforts to curb rapid population growth.

So what does the future hold and what can we do as ever stressed, helplessly broke students?

It has been projected by Hans Rosling and other prominent statisticians that by end of the century, we will be at the end of fast population growth. The number of children in the world will remain at 2 billion and not increase, but inevitably when they grow up, we will reach a steady state and our population will level off.

The most pressing obstacle we will face is resource scarcity, and without proper management, a waste explosion. We see these signs already today.


As students, we have the privilege of being in an environment where we are surrounded by many other like-minded people, and like packs of wild animals, if we work together, we will be more successful. So take control and encourage your university and the people around you to make changes. Promote energy saving alternatives, talk to your friends, your flatmates, educate them.

Explore ways to make reducing waste fun, label your bins and call out carless flatmates who don’t recycle. Join a protest, join a society, sign a petition which will make your opinions heard and encourage better and more sustainable change. Buy a long-lasting water bottle and use tap water, because heck, we spend enough money purifying that stuff and plastic bottles are not cool.

Take a walk, get a bike, reduce your time in a car and on those overcrowded buses. Change your diet, have a meat-free weekend or weekday? If demand goes down, so will supply. Because the more of us there are in the world, the more we have to share and nurture what we’ve got. Everything we do counts and more often than not, how we live our daily lives can be more powerful than any government incentive.

About the Author: Amy Beckford studies Environmental Geography at the University of York and has travelled to Honduras and Madagascar to further study her interests of sustainability and ecology.

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