P stands for 'pollution'
Pollution contaminates the natural environment with harmful substances produced by human activity.
An obvious example of pollution is an oil spill. This happens when oil is released accidentally into the sea from a tanker, pipeline or refinery. The spill forms a thin layer of oil, called a slick, poisoning sea life, and damaging the fur and feathers of seabirds and mammals.
Much more widespread forms of water pollution result from sewage or fertilisers making their way into rivers, lakes or the sea.
These increase the amount of algae and bacteria, which starve the water of oxygen as they decompose, threatening animal life.
Car exhaust fumes are an obvious form of air pollution.
Production in factories and other industry can have very serious effects on the environment by releasing molecules like sulphur dioxide or nitrogen oxide into our atmosphere. These molecules can dissolve in water droplets in clouds to form acid rain, which damages forests and kills fish and other water animals.
Carbon dioxide gas is naturally released when we breathe out, but burning fuels releases a lot more.
The gas builds up in the atmosphere and traps heat, causing the Earth's temperature to slowly rise over time. This is known as the greenhouse effect. Over time it will create many changes in climate, such as widespread floods and storms, which will have a negative impact on both people and natural environments.
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