Overpopulation is an existential threat to humanity

Large crowds gather in the afternoon on Cacuaco bay, north of Luanda, Angola. Credit: Getty Images / iStock / mtcurado

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We have read about the dangers of climate change and the potentially disastrous effects of growing levels of greenhouse gases in the atmosphere and increased temperatures — most recently detailed in warnings in a UN report. Still, we are rarely told about the single most important factor driving global warming, and that we have no plan to stop or minimize it: human population growth.

My parents were born in 1910 and 1911, when the world population was 1.7 billion. I was born in 1946, when the world population was around 2.5 billion. During my 70-plus years that population has tripled to 7.5 billion and is expected to reach 9.3 billion in the year I would turn 100. You don’t have to be a rocket scientist to understand that this growth is out of control and unsustainable. We won’t significantly decrease greenhouse gas emissions until we stabilize and decrease world population.

Global population has not increased uniformly. Despite the population increases of 1 billion South Asians and 850 million Chinese during my lifetime, there is little danger of a widespread ecological collapse or continent-wide famine in these two Asian regions in the immediate future.

But that’s not the case for sub-Saharan Africa. For reasons that include soil type, farming and pastoral patterns, historic low rainfall, weaker social infrastructure compared with Asia, and little technical irrigation, sub-Saharan Africa is dangerously close to an ecological collapse. Human population pressure and decreased and irregular rainfall have forced millions to abandon their pastoral and farming activities. In 2017, about 25 million sub-Saharan Africans lived outside their countries of birth. My colleagues working on agricultural research and development projects in Africa are concerned that, in their lifetimes, drought and population pressure will cause famine simultaneously in a number of sub-Saharan countries.

If there was ever a case where an ounce of prevention is worth a pound of cure, it is with imminent ecological disaster in sub-Saharan agriculture. Strategically placed wells and the planting of multi-purpose tree crops that fix nitrogen and provide animal feed and fuel can help stabilize pastoral systems, potentially save millions of lives and buy time to address the issue that Earth cannot sustain a population of 7.5 billion people, let alone the nearly 2 billion more projected by mid-century.

In the long term, we must begin a global conversation about how many people should live on planet Earth. This conversation will be difficult but it is necessary. Most of the overpopulated areas of the world have black, brown, or Asian populations. Who should tell Nigeria or Kenya to reduce its population or that India and China have a combined 500 million more citizens than is sustainable? This conversation will also be complicated because Canada and the United States annually produce 20 tons of carbon dioxide per capita, Germany and the Netherlands produce 8.5 tons, India produces 2 tons, and Nigeria 1.8 tons. If our goal is to reduce greenhouse gases as quickly as possible, reducing the United States or Canada’s population by 1 has the same effect on greenhouse gas reduction as reducing overpopulated Nigeria’s population by 11.

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We must start from the common premise that human population growth at current levels makes control of greenhouse gases impossible. The Earth will become increasingly uninhabitable during this century. Let us take our fate in our own hands and control our numbers in a humane and civilized manner before mother Nature does it for us.


Joel Levine is a retired agricultural scientist who has worked on USAID, World Bank and Asian Development Bank projects.