overpopulation causes effects and solutions

In the year 1800, there were approximately 1 billion inhabitants on Earth. In 1940, those numbers rose to 2.3 billion, then 3.7 billion in 1970, and about 7.5 billion today.

The United Nations has projected that this exponential population growth will continue: in 2030, the world’s population will likely reach 8.5 billion by 2050, 9.7 billion, and 10.4 billion by 2100.

Some experts say that since 1970, the world has been overpopulated. Overpopulation refers to the state in which the Earth cannot regenerate the resources used by the world’s population each year.

This nuanced trend has impacted everything from climate change to food resources worldwide. It’s critical to understand the factors enabling such rapid population growth and what we can do to curb the adverse effects of overpopulation.

In this guide, we’ll dive into all the overpopulation causes, effects, and solutions you need to know.

Is the world overpopulated?

The state of our Earth’s population has been fiercely debated for decades, with some deterrents stating that the concern of overpopulation is exaggerated. Many scientists state that human population growth will eventually end, and the United Nations also predicts that Earth’s population will not exceed 12 billion.

Regardless of which side you take in the debate, it’s true that a steadily expanding human population proposes immense challenges to all nations.

As The Overpopulation Project states, the Earth is overpopulated for two main reasons:

  1. Humans are rapidly displacing wildlife species across the globe.
  2. We are degrading ecosystems that provide essential, irreplaceable environmental services that future generations will need to live decent lives.

This reasoning is driven by the argument that Earth has never been equipped to house this many human beings. Today, we are not sharing Earth fairly with the millions of other plant, animal, and aquatic species that call it home.

overpopulated residential buildings
Human population growth undoubtedly poses challenges to all nations

Indeed, humans are consuming more natural resources than ever and encroaching on more and more natural habitats as the population has grown. It’s fair to assume that as the population keeps growing, so too will our damage to the Earth.

Only a few countries will make up over half the projected population increase by 2050: India, Nigeria, Pakistan, the Democratic Republic of the Congo, Ethiopia, Tanzania, the Philippines, and Egypt.

It’s important to understand that while population growth is highest in impoverished countries, consumption, carbon emissions, and resource use are far more significant in developed parts of the world. Thus, the environmental impact of each individual in wealthy countries is higher than in poorer countries.

What is causing overpopulation in the world today?

Now that we better understand the overpopulation debate and where population growth is occurring most rapidly worldwide, let’s examine the causes of this phenomenon.

Longer life expectancy

One of the most significant causes of overpopulation is what many would view as a positive development: the average life expectancy has continued to grow, and mortality rates worldwide have decreased in the last centuries.

Advances in modern medicine and increasing access to food and clean water are reasons life expectancy has continued to grow.

The World Health Organization (WHO) notes that global life expectancy at birth is expected to rise from 72.8 years in 2019 to 77.2 years in 2050. However, large gaps in this progress exist between the least developed countries and those that are more developed.

Death rates have also decreased: in 1973, the global mortality rate was 12.2 per 1,000 people, and in 2022, this rate decreased to 8.4 deaths per 1,000 people. While it’d normally be considered a positive trend, this increase in life expectancy means that the consumption footprint of each person also increases.

As people live longer and have children that, in turn, live longer, global demand for food and essential resources will continue to increase.

Underutilization of contraception and family planning

A 2019 study found that around half of the annual 21 million pregnancies in low- and middle-income countries in individuals aged 15-19 years were unintended.

They found that 8 million out of 9.5 million unintended pregnancies occurring annually in only twelve countries could have been prevented with modern methods of contraception.

These results illustrate the staggering effects of the lack of modern contraception on population growth. Underutilization of modern contraception occurs for a few reasons, including lack of access, fear of potential side effects, and lack of education on contraception and family planning.

Lack of access to contraceptives is an immense issue worldwide: around 1.2 million women live in a county without a single health center offering the full range of contraceptive methods.

A lack of adequate family planning also persists in many places. Family planning refers to the number of children a person wants to have. This right has been hindered in countries where there are gender or culturally-based barriers, a lack of access to adequate medical services, and where religious leaders reject the idea.

Better fertility treatment

Fertility treatment has become more advanced as medical care has improved globally, especially in wealthier countries where inhabitants can afford these treatments.

In the U.S., for example, more than 1 million babies have been born due to assisted reproductive technology since 1996. In fact, since 1978, the number of people conceived by reproductive technology has reached several million today and is rapidly approaching 0.1% of the total world population.

Over time, as more and more people utilize assisted reproductive technology, such as IVF, to grow their families, this portion of the population will continue to grow.

Migration and urban concentration

Today, cities worldwide are at the center of the overpopulation problem, and they’re continuing to grow.

 The top five most overpopulated cities are:

  • Tokyo, Japan: 38,140,000
  • Delhi, India: 26,454,000
  • Shanghai, China: 24,484,000
  • Mumbai, India: 21,357,000
  • São Paulo, Brazil: 21,297,000

These massive cities have been populated by migration and expansion for several reasons. People migrate from land damaged by climate disasters and flee social upheaval, conflict, and economic disparity.

While Tokyo and Delhi have experienced some of the highest economic growth in the world, these cities are not expected to grow much more. Instead, smaller cities in countries like India will continue to grow.

It’s projected that within 35 years, more than 100 cities will have populations larger than 5.5 million people. Where will these fast-growing cities be? By 2100, the world’s population centers are anticipated to shift to Asia and Africa.

What are the negative effects of overpopulation?

As more and more people are born, more food, clean water, energy, housing, healthcare, transportation, and energy are needed. This demand not only adds pressure to our already-strained resources but also increases the chance of conflict, large-scale disasters, and environmental degradation.

Let’s look a bit more closely at the negative effects of overpopulation.

Poverty and disease

Poverty is both a cause and effect of overpopulation. Social factors such as lack of education and reproductive care underlie both poverty and population growth, meaning that as long as these needs remain unmet, poverty and overpopulation will continue in a vicious cycle.

an aerial view of the slum in Mumbai
Slums in Mumbai – one of the world’s most populated cities

The UN projected that the total population of the world’s least developed countries is projected to rise from just over 1 billion people in 2020 to 1.76 billion in 2050. Overcrowding, especially in the most populous cities, leads to health issues caused by smog, pollution, and lack of access to sanitary personal and medical care.

In less developed countries with higher poverty rates, the mortality rate for children and adolescents is higher. In fact, scientists note that epidemics and pandemics are occurring at a more frequent rate and are being fueled by human overpopulation.

Ecological degradation

One of the most pressing effects of overpopulation is the damage our growing population is doing to our planet. Increasing global populations puts more pressure on our Earth’s resources, including our forests, water sources, and biodiversity.

As our cities become more populous and expand outward, we will continue to encroach on the habitats that animals rely on to survive. The increased use of natural resources, as well as added pollution and carbon emissions, will also ultimately exacerbate climate change and global warming.

aerial view of landfill on shore
Waste management is one of the big challenges that come with the population growth

However, experts also say that consumption is a large piece of the environmental puzzle. Consumption varies greatly between countries, and wealth plays a crucial role.

The UN reports that high-income and upper-middle-income countries contribute about 85% of global carbon dioxide emissions. Meanwhile, in these countries like the U.S. and Canada, fertility rates and the total population has continued to decrease.

Globally, the average carbon footprint is close to 4 tons, while the average carbon footprint for a person in the U.S. is 16 tons, one of the highest rates in the world. Thus, while birthrates fall in the U.S., each person’s impact is damaging our environment more.

Increased conflict

An additional negative impact of overpopulation is the increased occurrence of conflict. Most experts warn that overpopulation and a lack of resources will likely breed unrest and conflict.

A recent study found that population growth increased conflict related to natural resources in particular, especially in countries that are growing slower. The study found that the average population change caused roughly 4.2 additional years of full-blown civil war in the 1980s relative to the 1940s.

While the correlation between overpopulation and conflict is difficult to measure, it’s clear that when communities need to compete for natural resources, the chance of conflict is greater.

Child labor

When children are too young to work or are involved in work activities that compromise their physical, mental, social, and educational development, this is considered child labor.

little boy carrying can
Poverty often leads to the growth of child labor

While the dangers of child labor are clear, many families worldwide put their children to work for various reasons. The underlying causes and effects of overpopulation also contribute to increased child laborers, particularly poverty, lack of education, conflict, and natural disasters.

In the world’s least developed countries, slightly more than 1 in 4 children aged 5 to 17 are engaged in labor detrimental to their health and development.

When poverty levels are high, many families have no choice but to put their children to work. In this way, poverty exacerbates overpopulation because families need more children to contribute to the household. 

Tackling overpopulation: what are the solutions?

The negative effects of overpopulation are drastic and require multifaceted solutions that often go beyond the individual. Now that we understand the causes and effects of overpopulation let’s examine some of the main solutions to this issue.


One large part of combating overpopulation is improving reproductive education around family planning and contraceptive use. As we’ve established, lack of family planning – especially in poorer countries – is one of the main drivers of overpopulation.

Empowering women and girls to understand their options regarding family planning is crucial. More family planning programs should be implemented, especially in communities with high infant mortality rates and birth rates.

two young girls sitting on a bench
The lack of family planning education is one of the drivers of overpopulation

As the U.S. Center for Disease Control outlines, some of the elements of a successful family planning program include contraceptives and reproductive health surveys that provide high-quality data on various reproductive health indicators.

Education on family planning, reproductive health, and greater access to schools typically lead women and children to have fewer children. Thus, education is a huge part of decreasing birth rates in especially overpopulated countries.

Sustainable economic growth

As we’ve established, population growth over the next few decades will be driven by the world’s poorest countries. Because poverty worsens overpopulation and vice versa, investing in less developed countries with international aid, fair trade, and global justice will all help bring poverty and population rates down. 

In addition, we should strive for a more equal distribution of resources and transition towards more renewable sources of energy and production in all areas of the world.

One way to do so includes investing in research, development, and innovation to develop better production methods, improving the efficiency of our food production, energy distribution, water access, and more.

Environmental policy

In addition to decreasing birth rates, addressing the consumption of the world’s worst climate offenders is essential. As we know, people in high-income countries tend to overconsume resources.

Enacting policies and incentives that benefit the environment, limit carbon emissions, and protect resources on a national level will help curb some of the negative effects of overpopulation.

residential house with solar panels on a roof
Preserving natural resources on all levels can help curb the negative effects of overpopulation

While large corporations and the world’s wealthiest individuals are doing the most damage to the Earth, there are still things you can do to fight it. You can take steps in your life that help the environment, such as limiting your waste, using greener products, and adopting renewable energy sources.

Overpopulation causes, effects, and solutions wrap up

The overpopulation causes, effects, and solutions discussed in this guide are almost all interrelated. Various trends, such as poverty and climate change, serve as both causes and effects of overpopulation in many ways.

While there is no easy fix to these complex issues, looking at the whole picture of economic, social, and environmental factors is crucial when attempting to lessen the overpopulation problem.

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