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Every plant and animal species on Earth has evolved to live in a particular habitat with specific conditions regarding temperature ranges, predator/prey relationships, landscape features, and more. Human population growth is drastically altering these habitats. As human numbers increase, we demand more space and natural resources, but taking more for ourselves leaves less for other species. As the global population exploded in the past two centuries, we’ve entered an unprecedented age of wildlife extinction and biodiversity loss commonly referred to as the “Sixth Extinction.” This loss of wildlife changes and destroys ecosystems and poses threats to human health. Properly functioning ecosystems create the air we breathe, break down our wastes, provide our food, purify our drinking water, and provide the necessary resources to support human life.

Changing Landscape

In the next 30-40 years, the world population is expected to grow by an additional two billion people, and communities will require more homes, businesses, and roads to support their needs. Often, this results in habitat destruction through deforestation, filling wetlands, or flattening hills. Habitat fragmentation is also possible as roads limit animals’ movement on land or dams disrupt migration through water. Each year, up to 1 billion birds die from hitting glass surfaces in the U.S. while flying; glass skyscrapers in major cities like New York are especially treacherous. Pollution from noise, light, and waste also disturbs wildlife health and ecological processes.

Wildlife habitat is often destroyed when land is cleared to grow food and biofuel crops. More people also require more water resources, but dams and other water diversions built for irrigation and energy purposes can change and destroy the surrounding marine and freshwater ecosystems.


To produce more food, our growing population demands more production from current croplands. Current agricultural practices incorporate many chemical pesticides and fertilizers to produce larger crop yields. Pesticides are intended to kill pests like crop-eating bugs, but they also pose a risk to the health and welfare of non-crop-threatening animals in the area. Runoff from fertilizers is detrimental to the biodiversity of surrounding ecosystems as well. When fertilizer runoff enters streams, ponds, and eventually oceans, it promotes the growth of algae that rob the water of oxygen and cause dead zones in which water-dwelling species suffocate and die. Livestock runoff (manure) can create a similar problem in the water system, killing marine species and introducing disease-causing organisms, which, if present in sufficient numbers creates a health hazard.

Human-driven accidents like oil spills continue to be one of the major threats to marine ecosystems. Spilled oil can remain in the environment and its organisms for decades, and thousands of animals can die from a single incident.

Ecosystems Under Attack

Invasive species, non-native plants or animals brought to an area either intentionally or unintentionally, are a threat because they consume the habitat’s resources and can push out native organisms. For example, cane toads, indigenous to South and Central America, were released into Australia in the 1930s to prey on beetles thought to be destroying sugarcane crops. But now the toads have exploded in population because they have no natural predators and are consuming many resources, making it difficult for the native species to survive. 

Individual ecosystems are impacted in different ways by population pressures. Here are three examples, though there are countless others.

  • Coral reefs: Increasing demands for seafood encourages destructive commercial fishing methods, like deep sea trawling and the use of explosives, which destroy diverse coral reef habitats. Another threat, warmer water temperatures due to human-induced climate change, can result in harmful coral bleaching that causes corals to expel the algae living in their tissues, hastening their destruction.
  • Tropical rainforests: Rainforests are being clear-cut to provide for agriculture and grazing lands. They are also logged to provide raw materials for buildings, pulp for paper, and rubber products. Although tropical rainforests cover only about 6% of the Earth’s dry land, it is believed that they’re home to about half of all the species on Earth.
  • Arctic: Cooler climate-dwelling species may soon run out of habitat as global warming melts the Earth’s ice. In fact, the Arctic has already declined by over 43% since 1979. Many species, like polar bears, depend on sea ice to hunt prey, rest, and breed. These species may become endangered and even extinct over the next few decades as warmer conditions alter the habitat they depend on and human development blocks them from migrating elsewhere.

Impact on Humans

The loss of natural spaces has far-reaching effects on people and communities. Habitat loss of certain animals promotes the spread of disease. In some cases, disease-carrying animals come into closer contact with humans as housing developments push out into the animals’ territory. Growing populations also mean higher demand for meat, seafood, and other products derived from wildlife, which may carry diseases. For instance, seafood and wet animal market were instrumental in kickstarting the spread of the COVID-19 virus from animals, in which it originated, to humans.

Additionally,  one-quarter of all medications come from rainforest plants. Demolishing rainforests for human homes and industry destroys potential cures for human illnesses.