30 Things Scientists Say Will Happen if the Population Keeps Expanding

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30 Things Scientists Say Will Happen if the Population Keeps Expanding

The world’s population continues to balloon—we’re currently 7.6 billion people, according to the United Nations’ latest estimate. That’s pretty astonishing when you consider that, in 1900, the planet had just 1.5 billion people on it. As this growth shows no sign of slowing, it’s become increasingly important for the scientific community to assess the potential result of overpopulation. More and more people means fewer and fewer resources, which can create plenty of problems for the health of individuals and the planet as a whole, in ways that might surprise you—like these. And for more views of the future, learn the 30 Craziest Predictions About the Future Experts Say Are Going to Happen.

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Increased Rates of Respiratory Disease

The increase in air pollution inevitably leads to a rise in respiratory disease and asthma. Research has shown that air pollution can lead to worse asthma symptoms. For example, one study found that older adults were more likely to visit the emergency room for breathing problems when summer air pollution levels were higher. The worse air quality caused by overpopulation soon impacts individuals’ health.

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Severely Polluted Water

As the infrastructure supporting the growing population becomes overwhelmed, polluted water supplies can result. In India, Dr. Jayakanth M. J., an internal medicine specialist in Bangalore, has found that “People die each year because of contaminated water-related disease,” noting that filtering drinking water can sometimes fall short as a method for purifying water, especially when the number of drinkers keeps rising.

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Proliferation of Infectious Diseases

For any virus looking to spread, the more people and the closer they are to one another, the better. With the higher concentration of people resulting from overpopulation, the more likely infectious diseases are to spread. According to the World Health Organization, “inadequate shelter and overcrowding are major factors in the transmission of diseases with epidemic potential.” These include meningitis, typhus, cholera, scabies, and more. And for ways to prevent against unwanted illness, learn the 40 Ways to Never Get Sick After 40.

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Overwhelmed Hospitals

As has been seen after natural disasters that tax a city’s hospitals and health services, too many people and not enough medical resources can create a dangerous situation. The World Health Organization notes that when suffering from overcrowding, “public structures such as health facilities not only represent a concentrated area of patients but also a concentrated area of germs,” adding that, “Decreasing overcrowding by providing extra facilities and a proper organization of the sites or services in health-care facilities is a priority.”

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Exacerbated Climate Change

While global climate change is already rising dangerously, increasing the number of people on the planet will only intensify the problem. Travis Rieder, a moral philosophy professor and bioethicist at Johns Hopkins University, suggests that “we ought to consider adopting a ‘small family ethic’ and even pursuing fertility reduction efforts in response to the threat from climate change.”

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Suburban Sprawl

As overstuffed cities expand to accommodate additional people, many will develop areas that had been left alone, creating ever-expanding suburban sprawl. This causes plenty of problems, including infringing on natural local habitats. As the National Wildlife Federation puts it, “The conversion of natural areas for homes, offices, and shopping centers has become one of the most serious threats to America’s native plant and animal species”

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As researcher Max Katz-Balmes explains, “Overpopulation affects deforestation on a truly global scale, even in relatively uninhabited regions. From deforestation-overpopulation studies to date, a clear correlation exists between extremely low population density and maintenance of forests. Generalizing from these studies, at population densities less than two people per square kilometer, populations generally tend to be able to sustain themselves without agriculture and timber products.”

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Minimized Wildlife

Hand-in-hand with deforestation is the wider damage that development “around the world, in low-density regions as well as in high-density ones, population pressures create incentive to clear and develop land, in particular forests. Deforestation not only eliminates land and destroys ecosystems, but also fragments and changes many animals’ migration patterns and makes them easier targets for poachers.”

panda bear

Mass Extinctions

Yikes. All of this infringing on animals’ natural habitats will lead to major extinctions as vulnerable populations lose the precious little natural resources they have left. According to National Wildlife Federation, “nearly 20 plant and animal species become extinct every hour.” And for some much-needed good news here, learn the 15 Animal Species That Were Miraculously Saved From Extinction.

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Food Shortages

According to the Population Reference Bureau, one in eight people around the world suffered from hunger or undernourishment between 2010 and 2012. This is felt especially in overpopulated parts of the world where demand is far outpacing the supply of food—a situation that only increases as the population grows.

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Skyrocketing Food Prices

Overpopulation often can result in the driving up of food prices as production struggles to keep pace with the growing number of people. The Food and Agriculture Organization projects that food production must increase 70 percent by 2050 to keep pace with growing demand. “The world really has to sit up and pay attention,” Ngozi Okonjo-Iweala, a managing director of the World Bank, told Time. “The food security problem is a global security problem.” And if you need some tips on saving dough at the supermarket, learn the 15 Grocery Shopping Mistakes That Are Killing Your Wallet.

Doctor in surgical mask

More Effective Airborne Diseases

As people are in closer contact with one another, it becomes ever easier for airborne illnesses such as tuberculosis to spread. “There’s a strong correlation between the risk of pandemic and human population density. We’ve done the math and we’ve proved it,” Dr. Peter Daszak, a disease ecologist and the president of Eco Health Alliance, told Scientific American.

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Drug Treatment Declines

Just as overpopulation facilitates the spread of airborne diseases, it also hampers our ability to treat them. Looking specifically at the rise of Multi Drug Resistant Tuberculosis (MDR-TB), researcher Emma Griffith writes that, “Overpopulation is a systemic cause that contributes to the MDR-TB epidemic.”

Mosquito Bug-Bite

Malaria Everywhere

Overpopulation also makes it easier for infectious diseases such as malaria to spread between people. Urban crowding and environmental damage related to the excessive number of people can facilitate the transmission of malaria within a community.

HIV blood test

HIV/AIDS Proliferation, Too

Public policy organization Population Action International writes that “there is frequently overlap among countries with youthful populations, high rates of HIV prevalence, and low access to family planning,” giving the example of Swaziland, where 69,000 children have been orphaned by AIDS. The country has “been heavily affected by AIDS-related deaths among working-age adults and fertility remains at an average of four children per woman.”

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Clogged Morning Commutes

Of course, horrible traffic is one of the more immediate results of too many people. While infrastructure improvements can help alleviate some congestion, but the sheer numbers of cars filling the freeways and roads means that getting places will take much longer—to which anyone who has tried driving in concentrated metropolitan areas like New York City and Los Angeles can already attest. To make the most of your Monday-Friday slog, learn the Ways to Make Your Commute the Best Part of Your Day.

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Overcrowded Public Transportation

While driving anywhere becomes increasingly unbearable, the pressure a growing population puts on subways and other public transportation systems could be even more damaging. Major cities from New York City to Melbourne have already seen a crush of passengers cripple their ability to function at the levels they should be. (And don’t get me started on the difficulties in India.)

sunscreen application inside Skin Cancer Risks

Skin Cancer Rates Grow

As air pollution worsens due to the large number of people, it will cause a depletion in the ozone layer. As Dr. Jayakanth M. J. explains, this results in “the ozone layer of the atmosphere no longer protects us from the harmful ultraviolet (UV) rays of the sun causing skin problems such as skin cancers and premature aging of the skin. UV rays also result in a host of eye-related problems, such as cataracts and blindness. Most of all, it weakens the human immune system.” And for help on protecting against the disease, don’t miss the 20 Habits That Increase Your Risk of Skin Cancer.

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Access to Safe Drinking Water Limited

“One of the consequences of overpopulation is the pressure that is put on available water resources in order to serve a growing population,” writes researcher Daniel Altieri, pointing out that as of 2013, there are an estimated 780 million people without access to safe drinking water and two billion without water sanitation. “From the projected population size of around ten billion by 2050, the number of people who will live in urban areas is expected to increase almost two and a half billion people by that same year, on top of almost four billion people currently, putting the global urban population at about 65 percent in 2050.”

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Increase in Lung Cancer

Similar to asthma, according to Dr. Jayakanth M. J., the overpopulation of India and the toxic air that has resulted has led to increases in the number of people suffering from lung cancer.

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Throat Inflammation and Chest Pain Widespread

Dr. Jayakanth M. J. also has seen increasing numbers of complaints about chest pains and throat inflammation as terrible air resulting from too many people with too many cars makes daily breathing more uncomfortable.


Fish Vanish from the Oceans

As human populations increase their use of natural resources grows and tamps down the commercial fish stock available to eat. Dermot O’Gorman, the CEO of World Wildlife Fund Australia, writes that overfishing “is as much a humanitarian issue and one with profound implications for food security as demand for seafood grows and the world’s population marches.” He continues, “With many commercial fish stocks already in serious decline, it is clear we have an enormous challenge on our hands, made all the more urgent by the fact that global seafood demand is expected to grow another 50m tons by 2025.”

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Higher Crime Rates

As resources grow more scarce and other difficulties of living in concentrated, packed urban areas rise, so do crime rates. As Aisha Tariq of the Pakistan Times writes, “It has been observed that the countries which have balanced population, crime rate is very low in such regions. When people are not provided with the basic necessities, it elevates crime rate.”

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Rise in Air Pollution

The impact of overpopulation is not something scientists have to make abstract predictions about, since it’s already causing problems in several parts of the world. For example, India has been coping with overpopulation for years and offers a case study in the health troubles that can create. Dr. Jayakanth M. J. points out that, “with the increasing number of people traveling by their vehicle, there is a growing concern about the health impacts caused due to the traffic on the road.” How bad is the air pollution in India? According to the World Global Ambient Air Quality Database, 11 of the 12 most polluted cities of the world are in the country.

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The need for producing more food puts pressure on local and commercial farms to produce ever more and cheaper food. This leads to intensive consumption of plants by livestock, or overgrazing. This lack of rotation of the grazing animals and having them graze at inappropriate times can degrade the soil and lead to a range of other environmental issues. Such as…

Tick, ticks, pests

New Parasites

Intensive farming practices can lead to new parasites or the re-emergence of ones previously considered under control. “Furthermore,” according to environmental organization Everything Connects, “intensive farming kills beneficial insects and plants, degrades and depletes the very soil it depends on, creates polluted runoff and clogged water systems, increases susceptibility to flooding, causes the genetic erosion of crops and livestock species around the world, decreases biodiversity, and destroys natural habitats.

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Higher Birthrates

Overpopulation and its negative effects on the world and human health can create a vicious cycle. In overpopulated areas, as disease spreads and food shortages take their toll, birthrates often increase rather than decrease. “It’s fundamental in demographic transition theory that higher death rates lead to higher birth rates,” Jonathan Mayer, a medical geographer at the University of Washington, told The Atlantic. “Lots of kids die of malaria before age five, which means that people will have lots more kids to make sure some stay alive.”

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When dry land is overused, as tree and plant cover that would usually serve to bind the soil is removed, for cultivation or other purposes, it eventually leads to desertification. According to the International Fund for Agricultural Development, desertification threatens the livelihoods of some 1 billion people across 100 countries—a number that is only likely to increase as the population grows.

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Higher Unemployment

Unsustainable numbers of people can lead to fewer opportunities due to the lack of resources and greater competition for those that are available. This leads to what one academic panel referred to as, “an imbalance between the supply of labor and the demand for it gave rise to unemployment and underemployment. The vicious cycle generated by a high dependency burden associated with a young age-structure led to low savings and investments, which in turn led to low economic growth and a low standard of living.”

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Rising Conflict and War

On a larger scale, the strain overpopulation puts on resources and opportunities can lead to tensions between nations and communities, leading to conflicts over land ownership or supplies and potentially even wars. Population Institute president Lawrence Smith, looking at the conflicts of Angola and Sudan, says that while overpopulation “is not the exclusive factor. We just think it is such an important one that it is probably the key factor. Seventeen of the countries, for example, in the severe level [category] are going to more than double their populations by the middle of this century.”

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