Do you think that increases in the size of human populations and individual consumption of natural resources affect Earth systems? What evidence is there to support that statement? The population on Earth is over seven billion and growing. Yet scientists estimate that our total resources will only support two billion people. That means that we are consuming natural resources two to three times more than what is sustainable.

Human Impact on the Environment

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sustainable – not being harmful to the environment and not depleting natural resources

How have humans impacted the environment?Typically, as human populations and per capita consumption of natural resources increase, so do the negative impacts on Earth. What human activities have significantly altered Earth’s systems? We have changed the biosphere, lithosphere, atmosphere, and hydrosphere.

Human activity has sometimes damaged or destroyed natural habitats and caused the extinction of other species. But changes to Earth’s environments can have different impacts (negative and positive) on different living things.

per capita – for each personimpact – a strong effect

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Human Impact on the Environment

How do people have an impact on the biological systems on Earth? Human activities have a significant effect upon the biosphere, often in a negative way; however, some human changes to Earth’s environments can actually have a positive effect on living things. For example, look at the picture to the right that shows a sunken boat. What has happened to this man-made object? It is now the foundation of a new coral reef. Overall, do you think increases in the size of the human population and individual consumption of natural resources affect Earth’s systems? What evidence is there to support that statement?

Sunken boats are used to create artificial reefs to help rebuild a marine ecosystem’s wildlife.

biosphere – all the interconnected living and nonliving things on Earth

Oil spills and forest clearings are just two

ways humans negatively impact natural environments.

Negative Human ImpactThrough industry, agriculture, and simple everyday activities, humans can have a negative impact on the environment. What negative impact do you think each human activity has on the natural systems involved? Some examples are listed below.

Pollution: The top picture on the left shows pollution from the remnants of an oil spill that washed ashore. Oil spills damage marine habitats, can kill animals and plant species, decrease the amount of or the ability to do photosynthesis, and increase heat absorption of the oceans. A small oil spill can spread for miles and can affect ocean currents.

Deforestation: When forest ecosystems are systematically stripped of trees for the lumber industry or to clear land for agriculture (shown in the bottom picture on the left), habitats of various plant and animal species are wiped out, which can cause endangerment and, in some cases, extinction. As well, removal of forested land affects the carbon cycle and the global climate.

Water usage: Excessive withdrawal of water from streams and aquifers and the construction of dams and levees have negatively impacted freshwater habitats and the ecosystems that depend on those sources of water for food and shelter.

Land usage: Sustainable use of land has positive impacts on the environment. However, sprawling urban development, agriculture, and the removal of wetlands have damaged ecosystems and the wildlife in them.

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Human Impact on the Environment

What can be done to prevent or reverse the negative effects of human behavior?As individuals, people can reduce what they use, reuse or repurpose things when they can, and recycle items that need to be discarded. Recycling items helps eliminate waste that piles up in landfills. Landfills take over natural environments and impact the native species that once lived there.

Companies and industry leaders can fund the research of scientists and engineers. Their research should focus on developing new technologies that produce less pollution and waste as well as combat the extinction of native species. The consequences of increases in human populations and consumption of natural resources are described by science, but science does not make the decisions for the actions society takes.

The EPA also helps weigh the environmental costs of different human activities against their benefits to society. For example, if people in a city want to build a new bridge that would cut through an existing forest, they must submit a proposal to the EPA, outlining the benefits the new bridge would bring to the community as well as the potential harm to the natural environment. If the EPA deems the benefits are worth it, the project is approved.

Cleaning up pollution can also be a local effort, such as the project pictured on the right. The photo shows citizens with bags of debris they have collected along the shoreline for Operation Clean Sweep in San Diego.

What can local and federal governments do to prevent damage to the environment? In 1970, the Environmental Protection Agency (EPA) was formed to help combat some of the negative effects human activities have had on the environment. The EPA’s goal is to protect human health and the environment. The EPA makes sure that the environmental laws written by Congress and the regulations made to enforce those laws in the United States are followed.

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Human Impact on the Environment

Now it’s your turn to practice. Consider the negative human impact described in the left column of the chart below. Then explain a possible solution for it in the column on the right.

Negative Human Impact Possible Solution

Large sections of rain forest are burnedto remove trees and create farmland.

The building of a new subdivision forcesnative animal species out of their habitat.

A massive oil spill destroys marine habitatand significantly lowers marine populations.

A hydroelectric power plant requiresa dam that floods a nearby forest.