Indirect effects of pollution
Besides its direct effects, pollution has indirect effects that follow from the damage it does.
Loss of habitats
The natural environment in which a plant, animal or other organism lives is its habitat. As the environment is polluted, such habitats are lost to living things. Wild elephants, having lost their habitats, destroying village farmland is an indirect effect of pollution.
Desertification
Land becoming desert because it changes in a way unsuitable for plant growth is called desertification. Clearing forests, the greenhouse effect and rising salinity of farmland, as well as natural causes such as climate change, contribute. Droughts occurring when the monsoon rains fail to come on time are one result.
Lower crop yields
When plants do not get the factors needed for growth and photosynthesis properly, their yield falls, and so less food is produced. Using farmland continuously for cultivation makes the soil infertile, and polluted soil lowers crop yields.
Decay of built and natural heritage
Effects such as acid rain destroy metal statues, buildings, ruins and marble structures, and wear away natural limestone deposits. The rise in environmental temperature has put the walls and wall paintings of the Taj Mahal in India at risk of damage.
Health hazards
A dirty environment lets communicable and non-communicable diseases arise and spread fast. Diseases such as dengue spreading because rubbish is not disposed of properly are a result of pollution.
Why these effects are called indirect
A direct effect follows straight from the pollutant: acid in rain eats the statue. An indirect effect comes one step removed, through a change in the living world. Pollution destroys a forest; the elephants that lived there move out and eat a farmer's crops. A plastic bottle is not a disease, but lying in a drain it holds the rainwater where dengue mosquitoes breed. Indirect effects are often the harder ones to see coming, which is why understanding the whole ecosystem matters.
Damage that follows damage
Indirect effects include loss of habitats, desertification, lower crop yields, decay of monuments and the spread of disease.