Thermal Pollution: What It Is and the Effects on the Planet

, Staff Writer
Updated May 13, 2021
example thermal pollution in river
    example thermal pollution in river
    claudio.arnese / E+ / Getty
    Used under Getty Images license

Thermal pollution occurs when the temperature of a natural body of water is changed as a result of manmade actions. This results in the temperature of the body of water changing suddenly and drastically, which can lead to dangerous conditions for wildlife that makes its home in the water.

What Is Thermal Pollution?

Thermal pollution can be defined as an abrupt increase or decrease in the temperature of a body of water. This is very different from other types of pollution, which involve the release of toxic substances into the environment. Thermal pollution can be associated with toxic substances, but it doesn't have to be. Instead, anything that causes water temperature in oceans, seas or other bodies of water to rise or fall rapidly represents an example of thermal pollution.


Causes and Examples of Thermal Pollution

While there are a few natural causes of thermal pollution, it is primarily caused by the influence of humans. Manmade processes, such as manufacturing, power generation and land use development are the biggest culprits behind thermal pollution. There are many causes of and examples of thermal pollution.

  • manufacturing - Thermal pollution often occurs as a result of a manufacturing facility using water from a river to cool down equipment, then releasing it back into the river.
  • power generation - When water that has been used in nuclear cooling re-enters the natural water source from which it was drawn, it is much hotter than the water already in the river.
  • retention ponds - When water from shallow retention ponds is pumped to natural bodies of water, it is usually much hotter than the water it is entering. This leads to thermal pollution.
  • sewage - Untreated municipal sewage is often pumped into natural bodies of water. It is usually hotter than the water into which it is being pumped, so it causes a rise in water temperature.
  • deforestation - When trees are removed to make way for urban development, bodies of water once shaded from the sun now absorb more sunlight and thus experience elevated temperatures.
  • greenhouse gases - The increase of greenhouse gases in the atmosphere, much of which is attributed to deforestation and other manmade causes, leads to global warming and thermal pollution.
  • water runoff from roads - More development near the water means more paved roads. As more runoff passes over hot paved surfaces into natural bodies of water, the water temperature rises.
  • soil erosion - Soil erosion, much of which is caused by human factors, causes bodies of water to rise. Being elevated positions water closer to the sun, which can cause its temperature to rise.
  • natural causes - Natural sources of sudden water temperature changes include things like lighting strikes, underwater volcano eruptions or hydrothermal vents on the floor of the ocean.

Effects of Thermal Pollution

When the temperature of a body of water changes drastically, this can lead to several negative effects. Not only does it negatively impact the body of water itself and the marine life living in it, but it can also impact human beings and the planet as a whole.

  • An abrupt change in the temperature of a natural body of water causes the oxygen level in the water to diminish. Wildlife that lives in the water can suffocate due to insufficient oxygen.
  • Warmer water provides an opportunity for algae to flourish on the surface, a situation that can lead to an even further reduction of the level of oxygen in the water.
  • A drastic increase in temperature due to thermal pollution can lead to mass killings of fish and other wildlife. This will disrupt the natural ecosystem and can drastically reduce biodiversity.
  • When fish and other life forms that dwell in natural bodies of water die prematurely, this reduces the access that birds and other water-dwelling wildlife have to food.
  • Thermal pollution can also have a negative impact on whether or not water-dwelling animals will be able to reproduce and if their offspring will be able to survive to maturity.
  • Since many people rely on fishing as a way to earn a living or to get food to eat, thermal pollution has a negative economic impact and reduces human access to a nutritious food source.
  • Vegetation along the shore of the water can also be damaged or killed as a result of sudden, unnatural changes in temperature or oxygen levels in the water that nourishes them.
  • Damage to shoreline vegetation can lead to increased soil erosion, which in turn contributes to even more thermal pollution. As a result, thermal pollution becomes a vicious cycle.

How to Prevent Thermal Pollution

The key to preventing thermal pollution is to stop processes that lead to extremely hot water finding its way into natural bodies of water that have a significantly lower temperature. This could involve finding ways for water to be temporarily diverted away from industrial sites for cooling prior to entering natural body sources and seeking additional solutions for areas of development near bodies of water.

  • Building artificial lakes between roadways and natural water sources or using cooling towers at industrial sites could help to reduce thermal pollution.

  • Taking steps to reduce greenhouse gases can also have a positive effect.

Thermal Pollution and the Planet

Thermal pollution can lead to many negative effects on the planet, but there are ways to prevent this phenomenon from occurring. Now that you are aware of thermal pollution, consider exploring the difference between global warming and climate change. The more you learn about how to protect the environment, the better able you will be to advocate for positive change.