How Many People Can Planet Earth Support?

There are nearly 8 billion people living on Earth today, but our planet wasn't always so crowded. Around 300,000 years ago, our total population was small, between 100 and 10,000 people. There were so few people at the start, that it took approximately 35,000 years for the human population to double in size, according to Joel E. Cohen, head of the Laboratory of Populations at the Rockefeller University and Columbia University in New York City. 

After the invention of agriculture between 15,000 and 10,000 years ago, when there were between 1 million and 10 million individuals on Earth, it took 1,500 years for the human population to double. By the 16th century, the time needed for the population to double dropped to 300 years. And by the turn of the 19th century, it took a mere 130 years.

From 1930 to 1974, the Earth's population doubled again, in just 44 years. But will the human population continue growing at this rate? And is there an upper limit as to how many humans our planet can support?

Source: https://www.worlddata.info

In 1679, Antoni van Leeuwenhoek, a scientist and inventor of the microscope, predicted that Earth could support 13.4 billion people. He calculated that Holland occupied 1 part in 13,400 of Earth’s habitable land, and so multiplied Holland’s population of 1 million people by 13,400. Over 40 years of research Cohen has collected 65 estimates, ranging from 1 billion to over 1 trillion people. 

Engineers initially used the term "carrying capacity" to describe how much cargo a ship could hold. In the 19th century, wildlife managers then used the term in herd management, before scientists later applied the concept to ecology to describe the maximum population of a species that a given habitat could support. Within a habitat, a population will remain stable if birth and death rates are equal. But environmental changes, such as pollution or disease, can increase or decrease a habitat's carrying capacity. For instance, natural constraints include food scarcity and inhospitable environments. Human choices include interactions between economics, and culture, such as how we produce and consume goods, as well as birth rates, average lifespans and migrations.

Many low-income countries around the world have high birth rates and large family sizes, but also a high rate of infant mortality and shorter lifespans.  Global population growth peaked in the 1960s and has slowed since then. In 1950, the average birth rate was 5.05 children per woman, according to the UN Population Division. In 2020, it had fallen to 2.44 children per woman. 

The scientific consensus is that the population of the world will reach a peak some time later this century. The world population is projected to reach 10.4 billion people in the 2080s and remain there until 2100, according to the United Nations Population Division. 

The number of people Earth can support is not a fixed figure. The way humans produce and consume natural resources affects how our environment will be able to sustain future populations. 

One study published in the journal the Proceedings of the National Academy of Sciences found that if the population of the United States switched to a vegetarian diet, the land used to grow crops for humans rather than animal feed for meat production would feed an additional 350 million Americans. High-income countries, where females have increased access to education and family planning, tend to have lower birth rates and smaller family sizes than middle- and low-income countries.

So, what is the upper limit? Technology, climate, education, income and many other related factors all play a part in what could be an upper limit. From now to 2080, let us strive to improve quality of life on the planet rather than quantity!

Reference:

How many people can Earth support? Martin Mcguigan, www.livescience.com, July 11, 2022