This article covers an all too important relationship between environmental pollution and tropical rainforests, inlcuding the role of rainforests as pollution sinks as well as the sources & effects of rainforest pollution.
Pollution invariably disrupts the environmental services provided by tropical rainforests. Among other things, the rainforests serve as:
So these vital services are seriously disrupted by air, water and soil pollution which all cause damage to the rainforests and people living in or around them.
The big relationship between environmental pollution and tropical rainforests appears to be three-fold:
As an example of point 1, waste dumped into rainforests can be generated by industrial or agricultural activities. For instance, production of oil by Texaco in Ecuador rainforest led to this company dumping millions of gallons of toxic waste into pristine rainforests that acted as pollution recipients.
Point 2 is well illustrated by the process of rainforest destruction which leads to pollution of the forests and wider environment. Activities such as clearance of rainforests for growing “cash” crops, cause the release of carbon dioxide into the atmosphere and contribute to global warming. Here rainforests act as pollution sources.
In point 3, rainforests act in their unique capacity as pollution sinks – they remove carbon dioxide from the atmosphere and thus are capable of neutralizing pollution.
A sink is defined as “the process, activity or mechanism that removes a greenhouse gas, aerosol, or precursor of a greenhouse gas from the atmosphere” (1).
Another known type of greenhouse gas sinks are oceans.
As we know, greenhouse gases such as carbon dioxide (CO2) are serious pollutants which contribute to climate change on Earth, specifically global warming.
We have seen in point 3 above that tropical rainforests act as environmental pollution sinks.
For example, cars are among the biggest producers of CO2 emissions in the world.
Car emissions produced anywhere in the world may be absorbed and removed from the atmosphere by rainforests located in tropical countries. By absorbing these emissions, rainforests help relieve the global warming pressure.
So from this point of view, tropical rainforests are uniquely placed to help regulate and stabilize global climate patterns.
In other words, by acting as pollution sinks rainforests provide a common global good for the rest of humanity.
On the other hand, if rainforests are destroyed they will also act as major sources of global warming pollution.
This happens because rainforests are huge storages of greenhouse gases. And as a result of deforestation these greenhouse gases will be released back into the atmosphere and thus will further contribute to global warming.
Deforestation is a very serious problem - it has recently become one of the main causes of global warming.
Global warming may, in its turn, have a negative impact on the rainforests.
For example, warmer temperatures may cause an accelerated growth of pests which destroy the trees. Learn more about it in our article on effects of global warming.
So it is in the interest of all nations to have the rainforests intact and healthy.
Rainforest pollution has negative impacts on people, animals, trees & plants as well as the wider environment.
Sources of environmental pollution affecting rainforest ecosystems can be both natural and anthropogenic (human-caused).
Local Anthropogenic Sources and Effects of Rainforest Pollution
Agriculture is a well known source of environmental pollution, specifically causing ammonia emissions from livestock farming and animal waste.
Agricultural activities in rainforest areas are no exception to that.
But in addition to ammonia emissions, rainforest clearance by fire for agricultural purposes (especially cattle ranching) is also a source of harmful carbon dioxide emissions which contribute to global pollution and global warming.
Dark Clouds in Singapore
These clouds in Singapore originated in Indonesia as a result of illegal rainforest burning by farmers to clear land for plantations and other purposes.
Photo: Seema K K
Below is a summary of agricultural contribution to rainforest pollution:
- Use of “slash and burn” method to clear land for agriculture; the burning process releases carbon dioxide into the atmosphere contributing to air pollution and global warming
- Rainforest soils are poor in nutrients; this leads settlers to continuously seek new land and clear even more rainforest by burning
- Where there are human settlements, there will always be human-generated waste left behind causing further rainforest pollution
- Forest clearance by fire for cattle ranching releases more carbon dioxide into the atmosphere further contributing to environmental pollution and global warming
- Overgrazing causes severe soil degradation (2)
- Contributes to ammonia pollution
“Cash” crops growing:
- Widespread use of p esticides (for example, for soybean or sugarcane cultivation) (3) may lead to major pollution of water and soil
- On the positive side, nitrogen pollution coming from the use of nitrogen fertilizers can actually boost the growth of plants in tropical rainforests (4)
It’s not difficult to imagine that industrial sources are major contributors to rainforest pollution.
Some of the most important industrial activities causing pollution are summarized below:
Logging / Timber extraction (5)
- Waste wood chips (“slash”) from logging left behind pose a danger in case of forest fires
- Use of heavy machinery may lead to soil compaction as well as leaking of oils used for managing such machinery
- Removal of trees can cause nutrient depletion [for rainforest ecosystems]
- Removal of trees leads to the release of carbon dioxide into the atmosphere contributing to air pollution and global warming
- Logging companies will often slash and burn large areas of forest just to get access to one commercially valuable tree; such [mindless] forest burning will release more carbon dioxide into the atmosphere (6)
- Logging leads to deforestation / rainforest destruction and the loss of potential pollution sinks and their ability to remove carbon dioxide from the atmosphere
- Land cleared by logging helps new farming settlers make their way into the rainforests and cause more deforestation / pollution
- Logging also destroys rainforest animals’ habitat; many of rainforest animals are now endangered due to habitat loss and environmental pollution
- Mercury used in extracting the gold during the “Gold Rush” of the 1980s in Brazil’s Amazon, polluted waterways causing the fish to be inedible (7)
- During mining activity, blasting releases particles and noxious fumes; the winds blow across open-cast mines, waste heaps and dumps of toxic mined products like asbestos, spreading the pollution (8)
- Dust from mining can also negatively affect agricultural fields (9)
Hydropower is a major source of energy supplies in developing rainforest countries. For example, around 83% of total power production in Brazil in 2004 came from this source. (10)
Itaipu Dam, Largest Dam in the World
Large areas of the rainforest were destroyed and many people displaced during the construction of this dam.
Construction of dams used to generate hydroelectric power is a serious cause of rainforest pollution.
The effects of dam construction on rainforests are as follows (11):
- Large areas of the rainforest are flooded, thousands of people living in the vicinity are uprooted and moved
- Rates of waterborne diseases increase
- Dams trap silt that contains valuable nutrients for aquatic life, thus damaging downstream ecosystems
- Reduced levels of silt cause coastal soil erosion
- Water pollution that damages and kills aquatic life
EXAMPLE: – the Balbina dam, Brazil (12):
- 1,400 sq. miles of rainforest flooded, with trees rotting in water
- Water pollution:
- Water acidified, undrinkable with heavy metal pollution
- Large number of fish have died
Oil production and its related activities are infamous around the world for their capacity to bring pollution upon virtually any life-hosting environment that comes in contact with them, including water, soil and air.
Oil-related activities have been known to pollute vulnerable and highly valuable rainforest ecosystems as well. An excellent example of that is the above mentioned case of Ecuador rainforest pollution by Texaco oil operations.
Below we discuss some effects of oil production on people and rainforest ecosystems:
- Oil spills in coastal areas as well as on land due to oil production and transportation cause water pollution, soil pollution and air pollution. Some of the effects are as follows:
EXAMPLE: – The Niger Delta case:
5 to 10% of all mangrove forests of the Niger River disappeared as a result of oil spills aggravated by human impacts. It is assumed that this happened due to high toxicity of oil and its ability to evaporate easily and penetrate living components of the surrounding ecosystems. (14)
- Natural gas flaring as part of oil production releases methane and carbon dioxide (greenhouse gases) into the atmosphere contributing to air pollution and global warming. Other toxic chemicals are also released – nitrogen dioxide, sulfur dioxide, volatile organic compounds (VOCs). These chemicals may cause acid rain with all its consequences on humans, animals and rainforests. (15)
- Construction of oil producing facilities as well as pipelines may itself require clearances of large chunks of rainforests, which will most likely bring up further environmental pollution issues.
EXAMPLE: – The Chad–Cameroon Pipeline:
The pipeline cuts through the coastal Cameroon rainforest. Project-related construction of roads led to illegal poaching and logging (with all the environmental consequences resulting from it). Construction already caused oil spills and pollution of drinking water. (16)
Large industrial projects (such as the mining and logging ones described above) require road infrastructure for their successful implementation.
Not only does construction of road networks through rainforests lead to rainforest pollution and destruction of animal habitats, but it also opens the forests up and facilitates settlements of human populations alongside these roads. This causes further rainforest pollution associated with human settlements, and so the cycle goes on and on.
Global Anthropogenic Sources of Rainforest Pollution
Since tropical rainforests act as global pollution sinks, this means they are also affected by air pollution (specifically greenhouse gases) coming from different parts of the planet.
Most anthropogenic greenhouse gas emissions come from the burning of fossil fuels in industrial production, various industrial processes, commercial and residential sectors, and in road transport; also from deforestation and agricultural activities. (17)
Natural Sources of Rainforest Pollution
Wild forest fires and volcano eruptions are some of the natural sources of rainforest pollution.
Alongside the structural changes to rainforest ecosystems resulting in widespread pollution (as we described above), rainforests have to deal continuously with ongoing pollution processes affecting their health.
Specifically, we refer to air pollution which knows no borders and can pose serious, albeit invisible, danger to forests and their animals.
As already mentioned, air pollution affecting rainforests comes from both local and global sources.
Rainforests can neutralize some forms of air pollution (for example, removal of a certain amount of CO2 from the atmosphere) while unable to resist other pollution types (for instance, acid rain).
There are many types of air pollutants that will negatively affect the health of rainforests and animals residing within them.
Some of the effects of air pollution on humans, such as problems with the respiratory system due to ozone pollution, may also apply to higher forms of animal life.
Apart from carbon dioxide emissions, acid rain is possibly one of the more serious types of rainforest pollution.
- Can slow growth of forests and cause leaves to fall off (18)
- May affect forests’ soils by depleting vital nutrients and minerals (19) and indirectly harm growth of trees
- May cause reduction of forest yields
- Can seriously harm rainforest aquatic life
For further details of acid rain effects, please see the Air Pollutants Summary.
Environmental pollution is a global problem, and the rainforests are not immune to it.
The global importance of the rainforests is very clear – among many other things, they act as pollution sinks and help fight global warming.
We have a “double whammy” situation here: on the one hand, clearance of the rainforests causes environmental pollution; on the other hand, the cleared rainforest area is lost as a pollution sink which even further magnifies the global pollution problem.
It is therefore the responsibility of the whole international community to come together and make sure rainforests are kept healthy and safe, to ensure our own survival.
Written by: Irina Bright of Tropical-Rainforest-Animals.com
Publication Date: April 2008
Updates: October 2011