How Humans Impact The Carbon Cycle

Article about how humans impact the carbon cycle.

            There are three major cycles of matter in ecosystems. These cycles are the carbon, phosphorous, and nitrogen cycles. Humans impact each of these cycles in different ways. Each way has negative effects on our planet, and will be discussed.

            The carbon cycle starts with carbon dioxide that is in our atmosphere. It flows into our plants through photosynthesis and additional metabolism. According to Boorse and Wright (2011, p.67), “The carbon atoms can then be eaten and become part of the tissues of all the other organisms in the ecosystem.” Half of this is breathed into the air by plants and animals and the other half is dumped into the soil in the form of dead plant and animal matter. Finally, organisms in the soil that eat dead matter breathe the carbon back into the atmosphere.

 Humans have affected this cycle significantly. We are constantly increasing the amount of carbon dioxide in the atmosphere. This is done by deforestation, soil degradation, and the burning of fossil fuels. When we burn coal, the carbon that had been trapped when it was underground is released into the air. The increase of carbon in our atmosphere is surely leading to the greenhouse effect which some say is the reason for our rapidly changing temperatures and the natural disasters such as tornadoes and hurricanes that are becoming more common. Through reforestation and some changed agricultural practices, we have somewhat improved the mess that we have already created. (Boorse and Wright, 2011, p. 68)

The phosphorous cycle is a slow process. As rocks slowly break down, phosphate and other ions are released (Boorse and Wright, 2011, p.68). Next, plants absorb the phosphorous from the soil or from water. The plants are then eaten and it begins to move through the food chain. From there, the organic compounds that hold the phosphorous are then broken down in cell respiration or by decomposers, and are released into urine and other waste material (Boorse and Wright, 2011, p. 69). Finally, it is reabsorbed by plants and the cycle starts all over.

This cycle, like the carbon cycle has been affected negatively by humans.  Through using fertilizers, animal feeds, detergents, and other products made with mined phosphorous, we have tripled the amount of it in the oceans (Boorse and Wright, 2011, p. 69). Because there is really no way to return this phosphorous to the land from these aquatic ecosystems, they become over fertilized, which leads to severe water pollution that causes “the overgrowth of algae, too many bacteria, and the death of fish.” (Boorse and Wright, 2011, p. 69)  

Just like the carbon cycle, the main reservoir, called nonreactive nitrogen, is in the air. The other forms are called reactive nitrogen and are what plants take up as ammonium ions or nitrate ions that are then integrated into vital organic compounds such as proteins and nucleic acids (Boorse and Wright, 2011, p. 70). Once in the plants, they are then moved into consumers and decomposers (Boorse and Wright, 2011, p. 70). Mostly through ammonium compounds, nitrogen wastes are freed. Finally, nitrifying bacteria oxidizes the ammonium to nitrate that produces energy for the bacteria, and is then ready to start the cycle over.

While they benefit human welfare intensely, the human involvement through agricultural crops, both leguminous and nonleguminous, and also through the fossil fuel combustion, causes major problems in our ecosystem. “Nitric acid has destroyed thousands of lakes and ponds and caused extensive damage to forests.”(Boorse and Wright, 2011, p. 70) Our interference with the natural nitrogen cycle has contributed enormously to greenhouse gasses, global climate change, and stratospheric ozone diminution. It has also caused mineral deficiencies in many producers. The presence of the extra nitrogen in estuaries and the coastal areas of oceans have killed seafood, caused damaging effects on human health, and has made some parts of the oceans unfit for fish to live in.

Overall, human involvement in these cycles has impacted them extremely negatively. Just from changing the natural levels of these cycles, we have caused climate change, created the greenhouse effect, increased natural disasters, killed fish, both fresh and salt water, and affected our own physical health. In some ways, we have benefited ourselves, but the negative effects on the ecosystem have outweighed all of that.




Boorse, D. F., & Wright, R. T. (2011). Environmental science: Toward a sustainable future. (11 ed.). San Francisco, CA: Pearson Benjamin Cummings.

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