What is Thermal Pollution?

Jessica Ellis
Jessica Ellis

Thermal pollution refers to an increase of temperature in a body of water due to human or environmental causes. While a degree or two of difference may sound minor, warming of an aquatic or marine environment even by a small amount can result in devastating alterations to the habitats of fish, insects, plants, and animals. There are several main causes of thermal pollution, each contributing to what some environmental experts call a possible environmental catastrophe.

Using water as a coolant adds to thermal pollution.
Using water as a coolant adds to thermal pollution.

One of the major causes of thermal pollution is industrial use of water as a coolant. Factories and power plants typically use nearby sources of water to keep machinery cool and functional. While inexpensive and effective, this form of cooling process can wreak havoc on aquatic ecosystems. Water is typically siphoned away from a source, run through cooling systems at a factory or plant, then returned to the original source.

Unfortunately, in the process of cooling machinery, the water temperature rises, sometimes by several degrees. The influx of warm or hot water back into a natural source can destroy food sources or kill off species that require a certain temperature to survive. Many environmental scientists consider the industrial heating of water to be the largest factor in localized thermal pollution.

Soil erosion and deforestation are two other major factors that can lead to unnatural increases in temperature. Shore plants and trees help shade water, keeping temperatures in check by providing protection from sunlight. When plants are removed, not only does a body of water absorb more sunlight, soil held in place by root structures falls into the water. Soil erosion can cause river and lake beds to rise, creating shallower pools of water which heat more quickly.

One of the primary causes for concern with thermal pollution is the depletion of oxygen in the water. Fish rely on a certain amount of oxygen to survive underwater; they do not easily adapt to oxygen level shifts. The warmer water is, the less oxygen it can hold, making a flourishing ecosystem turn deadly for inhabitants in a short time. Additionally, shallow and warmer waters increase the production of oxygen consuming plants such as algae, which decrease oxygen levels even farther as they decompose.

There are several ways to help mitigate the effects of thermal pollution in order to stabilize and sustain aquatic environments. Factories that use water as coolant can install cooling towers and ponds which return water to original temperature before releasing it back into the natural source. Ensuring that banks and shorelines have adequate vegetation to provide shade and retain soil can also help prevent thermal pollution.

Jessica Ellis
Jessica Ellis

With a B.A. in theater from UCLA and a graduate degree in screenwriting from the American Film Institute, Jessica is passionate about drama and film. She has many other interests, and enjoys learning and writing about a wide range of topics in her role as a wiseGEEK writer.

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Discussion Comments


Industrial pollution poses a serious threat to well being in third world and developing nations. In some places in Eastern Europe, people do not value natural life, and let their industrial practices hurt the rest of the world. The sooner the world realizes that we're all in this together and need to care about each other the better.


Ocean pollution has become a large problem, especially with the recent oil spills in the Gulf of Mexico. The sooner we switch to alternative forms of energy besides oil the better. We are mixing natural substances which were not meant to be mixed: oil was meant to stay well below ground, and now it is washing up on shores everywhere.



It is quite sad to note how people living in a polluted environment realize that they have to be either a victim or a prey, and join in the big factory living, in order to make money and escape the harsh environmental conditions. In working for these factories, they contribute to the low life expectancy and hardship of those living around the factories.


Environment pollution is a leading cause of death to both animals and humans. People who are forced to eat contaminated fish and other animals or substances affected by pollutants can put their health at serious risk. Making sure that this risk is eliminated by keeping rigid legal environmental rules for companies can ensure the general well-being of the earth and of creatures which are forced to live in such environments.

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