Main Pollutants and Their Origins
Growing human populations across the world have led to an unprecedented increase in energy demand. This demand is met largely through the use of fossil fuels, coal, oil and natural gas, which release large quantities of pollution into the atmosphere during their extraction and use, i.e., when they are burnt to provide energy. The main pollutants released include carbon dioxide, methane gas, nitrogen oxides, sulfur dioxide and carbon monoxide.
Pollution and Global Warming -- The Greenhouse Effect
The greenhouse effect is a natural process in which energy from the sun is trapped by the Earth's atmosphere, allowing the planet to warm enough to support life, as explained by BBC News. In terms of increases in global warming, the greenhouse gases carbon dioxide, methane and nitrogen oxides are particularly important. A buildup of these gases from human activities, such as burning fossil fuels and deforestation, has led to an intensification of the greenhouse effect, consequently trapping more heat within the atmosphere and heating the planet. It is believed by many scientists, such as those researching for the Intergovernmental Panel on Climate Change (IPCC), that increased greenhouse gas emissions are exacerbating global warming.
Global Dimming
Another effect of pollution on the Earth is that of global dimming. Global dimming is a process in which airborne particles, released since the start of the Industrial Revolution, gather in the atmosphere and reflect heat back out to space, as explained by the Natural Environment Research Council. This process cools the Earth. However, particle pollution, which forms the airborne particles responsible for global dimming, is being reduced, whereas emissions of carbon dioxide and other greenhouse gases are increasing. Thus, according to one of the world's leading climate modelers, Peter Cox, the cooling effect from one type of pollution will be lost, whereas the heating effect from greenhouse gases is projected to increase, leading to the potential for greater warming.
Other Effects of Pollution on the Earth
In addition to the effects on global warming, pollution has many other detrimental impacts on the environment. Sulfur dioxide, for example, combines with water vapor in the atmosphere to produce acid rain. Acid rain has detrimental effects on rivers, lakes and soils. According to the National Geographic website, the acid rain makes rivers and lakes acidic, causing them to absorb aluminum from the soil, making the water toxic to aquatic animals. Other pollutants, such as nitrogen oxides and volatile organic compounds, can react in sunlight to produce ground-level ozone, a primary constituent of smog, which can have adverse respiratory health effects on humans, as explained by the U.S. Environmental Protection Agency.