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17.12: Overpopulation and Over-Consumption

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    Is life the same for all 7 billion of us?

    No. A minority of people use most of the world’s energy and other resources. Not only are their needs met, but they have many luxuries. Many other people lack resources. Many don’t have enough to eat or live, with the threat of hunger. Many also do not have safe, clean water. Some people live in crowded, run-down housing. Some people live in mansions.


    Overpopulation takes place when the number of organisms exceeds the carrying capacity of the region. What is the carrying capacity of Earth for humans? Are seven billion people the human carrying capacity? Nine billion? We don't know yet.

    It seems that we have increased the carrying capacity of the planet for humans. We have done this with agriculture and fossil fuels and improvements in health care. Have we now exceeded Earth's carrying capacity (Figure below)? Are humans on Earth experiencing overpopulation?

    Manhattan, one part of New York City, is one of the most heavily populated regions in the world

    Manhattan, one part of New York City, is one of the most heavily populated regions in the world.

    There is not yet an answer to that question. So far, many of us have skated along without much trouble. But since we depend on resources that are non-renewable, the answer could well be yes. Either way, we face very serious problems, like climate change, that could devastate the human population and the world.

    Human Population and the Environment

    There is evidence that there are too many of us; that the large population is becoming too high. That’s because we are harming the environment. Some of the harmful effects of a high human population are:

    • Supplying all those people with energy creates a lot of pollution. For example, huge oil spills have killed millions of living things.
    • Burning fossil fuels pollutes the air. This also causes global warming.
    • Fossil fuels and other resources are being used up. We may run out of oil by the mid-2000s. Many other resources will run out sooner or later.
    • People are killing too many animals for food. For example, some of the best fishing grounds in the oceans have almost no fish left.
    • People have destroyed many habitats. For example, they’ve drained millions of acres of wetlands. Wetlands have a great diversity of species. As wetlands shrink, species go extinct.
    • People have introduced invasive species - species originally from a different area—to invade new habitats. The introduction can be intentional or accidental. Often, the aliens have no natural predators in their new home. They may drive native species extinct. In the mid-1900s, Australian tree snakes invaded Guam and other islands in the Pacific. The snakes stowed away on boats and planes. Tree snakes had no natural predators on the islands so their population exploded. The snakes have caused the extinction of nine of the eleven native bird species on Guam (Figure below).

    A brown tree snake, an invasive species

    A brown tree snake.

    • People themselves are also affected by the large size of the human population. Some people have a lot; some have very little. Many people refer to the abundance of luxury items in some people’s lives as over-consumption. People in developed nations use 32 times more resources than people in the developing countries of the world. The symbol of this is CO2 emissions, which are a waste product from fossil fuel burning. Populations that burn the most fossil fuels have a high standard of living.

    Map of carbon dioxide emissions

    CO2 emissions tell which countries are using the most fossil fuels.


    • Supporting 7 billion people is taking an environmental toll on the planet.
    • Pollution, habitat destruction, and invasive species are a few of the problems caused by the high population.
    • Over-consumption means that some people use a much larger amount of the resources than others.


    1. What are some of the ways that the large human population is harming the environment?
    2. What are invasive species? Why are they able to do so much damage?
    3. What is over-consumption?

    Explore More

    Use the resource below to answer the questions that follow.

    1. What was the prediction made about world population in SciShow’s early episode on Overpopulation?
    2. What will happen to the size of the human population by 2100?
    3. What is Total Fertility Rate? What has been happening to this number since the 1960s and why?
    4. What is happening to Total Fertility Rate in Africa? Why does that affect the future prediction of population?
    5. How could the average woman give birth to 0.8 children in her lifetime in Singapore? (What is 0.8 child?)
    6. Why is Africa’s total fertility rate relatively high?
    7. How many people are predicted to live in sub-Saharan Africa by 2100?

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