The Complete Guide to Thermal Pollution

Thermal pollution can be as dangerous as waste, personal pollution, and carbon emissions. However, people seem to not think about thermal pollution when the word ‘pollution’ comes to mind. Thermal pollution is a persistent problem. Usually, it happens when a human-made organization or an industry takes water from a natural source and either heats it up or cools it down.

Then, they will eject that water back into its natural environment, all of a sudden altering the oxygen levels. This technique can have terrible effects on communities and local ecosystems. Therefore, thermal pollution is the sudden decrease or increase in temperature of a natural body of water, which may be a pond, river, lake or ocean, via human influence.

This may occur when a facility or plant takes water from a natural resource and then puts it back with a different temperature. Most likely, some of these plants and facilities use it a cooling method for their machinery.

However, waste water facilities or plants which produce different products are the ones to be blamed for this huge exodus of thermal pollution. Even if many governments and organizations around the world have tried to diminish the dangerous effects of this type of pollution, they have not annihilated the problem. The terrible effects still linger today.

Causes of thermal pollution

Urban runoff

Runoff from paved surfaces can also trigger thermal pollution. When urban runoff is discharged into water, it can determine a terrible increase in water temperatures. During the warm season, the pavement can be quite hot, developing warm runoff which gets into water bodies and sewer systems.

Cooling agent in industrial plants

Specialists indicate that manufacturing and production plants are some of the primary sources of thermal pollution. They draw water from natural water sources to maintain their machines at a certain temperature and then release it back with higher temperature. Therefore, when this heated water follows its course back into the lake or ocean, the overall water temperature rises, and oxygen levels are altered.

Unfortunately, the variations of oxygen levels can affect the longevity and quality of wildlife in the area, disrupting several ecosystems. Besides affecting the sea animals, this phenomenon can also wipe away thousands of species of marine plants which are dependent on constant temperatures and oxygen levels.

Industries are contributing to the decrease of the marine creatures’ life quality, destroying many habitats when altering natural water sources. If these practices are not controlled, the effects can be devastating.


When plants and trees are cut down, all the sunlight will fall directly on rivers, ponds, and lakes, heating the water. Therefore, deforestation is another terrible cause contributing to thermal pollution and affecting many species of animals and plants. Without the trees and plants around the rivers and lakes, the water is likely to heat due to direct sunlight. Besides causing thermal pollution, deforestation is also responsible for the emission of greenhouse gases.

Soil erosion

Soil erosion also contributes to thermal pollution, causing water bodies to increase. In this way, they are clearly more exposed to sunlight, and the water temperature is likely to grow. The high temperatures can severely affect the marine life, proving to be deadly for aquatic biomes, fueling the occurrence of anaerobic conditions.

Natural causes

Geothermal activities and volcano eruptions under water can also cause thermal pollution. When warm lava raises, the temperature of those water bodies also increases, affecting many marine habitats. Furthermore, lightening can also discharge a massive amount of heat when striking into the ocean. Therefore, the overall temperature of the water can increase, negatively impacting the environment.

Two fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province

Thermal pollution can cause changes in the reproduction process of plants and animals due to warm water.

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The effects of thermal pollution

This type of pollution is detrimental when it comes to positive environmental practices. However, we should also think about the terrible impact it has on marine ecosystems. Some people may say that it will be harder without these industries that operate in this way. They believe that some of the basic things we’d do today would be obsolete if we were to eliminate thermal pollution.

We would not have the industries we have today to produce the goods we need. Nevertheless, the terrible effects of thermal pollution on ecosystems definitely outnumber the benefits obtained by certain industries when participating in the act.

Loss of biodiversity

If the biological activity in the natural source of water is disrupted, then it may trigger a massive loss of biodiversity. The changes that will occur in the ecosystem can trigger different species of organisms to shift their base to other places. Organisms which can easily adapt will have an advantage over those organisms which cannot adapt to warm temperatures.

Decrease of dissolved oxygen levels

When the industries discharge the warm water back into the natural body of water, it reduces the levels of dissolved oxygen. We all know that warm water contains less oxygen compared to cold water. Therefore, this drastic decrease in oxygen levels can determine the suffocation of marine plants and animals, affecting copepods, amphibians, and fish. This can trigger the occurrence of anaerobic conditions.

Furthermore, warm water can trigger an abnormal growth of algae which will slowly surface the water. Over the long term, this phenomenon will decrease the oxygen levels in the water.

Increase in toxins

The constant flow of high-temperature discharge from industries will trigger a rise in toxins. These toxins reach into the natural body of water whenever warm water is discharged back into the natural source. The discharged chemicals can contain radiation and chemicals which may have a massive impact on the local ecology. Furthermore, they may also pose a serious threat to nearby communities, being susceptible to different illnesses.

Affects the reproductive systems

Thermal pollution may also affect the reproduction processes of marine wildlife. Even if reproduction may still occur, the newborns may be born with multiple defects because of the increasing temperatures. Furthermore, excessive temperatures can also determine the release of immature eggs.

Summing up

All these causes and effects of thermal pollution should increase awareness regarding the protection of the environment. Thermal pollution is a severe threat to many ecosystems, affecting the reproduction and developmental processes of many species of marine animals and plants. Authorities should definitely control these industries’ practices to avoid the disruption of marine habitats.

Image Source: Greentumble

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William E. Eubanks

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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