Air pollution from factories is a serious environmental problem.
Environmental problems can be found in all parts of the world and affect land, water and air. Some result from what humans take from the environment, in the form of land for agriculture and accommodation for a rapidly growing population; mineral and fossil fuel resources; and wood. These problems include deforestation, erosion, damage to ecosystems and reduced biodiversity. Other problems stem from what humans put into the environment in the form of various pollutants. These issues include climate change, damage to the ozone layer, urban pollution, and acid rain.
Clear cutting is a form of environmental degradation.
One of the most publicized aspects of degradation is deforestation. In the Amazon rainforest in particular, trees are being cut down at an alarming rate to provide more land for agriculture. This is threatening the survival of many animal species, for example the jaguar. In Borneo and Sumatra, another forest animal, the orangutan, is threatened for the same reason.
Environmental scientists use samples collected in the field to track air, water and soil quality.
Deforestation can also lead to soil erosion. Trees stabilize the soil with their roots, reduce the amount of rain that hits the ground, and help the soil retain moisture. When they are removed, heavy rain can quickly wash away dirt, and during periods of drought, bare, desiccated soil can be removed by the wind. Deforestation on hills and mountain slopes can lead to flooding, as water can then run unimpeded down the slopes, and can also result in disastrous landslides.
Water polluted by an oil spill.
In some cases, successful campaigns have been launched to alleviate some of these problems. For example, in the United States, logging in forested areas was destroying the habitat of the endangered northern spotted owl. After a lengthy court process, however, logging was restricted in these areas. Since 2013, campaigns have been underway to save a variety of endangered animals.
Soil erosion can expose tree roots and uproot forests.
This is a global problem that affects the atmosphere, oceans, lakes and rivers, as well as the land. Many human activities result in the release of toxic chemicals into the air or water, which can harm the environment or cause health problems for people. Two of the worst air pollutants are sulfur dioxide (SO 2 ) and nitrogen dioxide (NO 2 ). SO 2 is produced by sulfur compounds in fossil fuels, particularly coal, while NO 2 comes mainly from automobile exhaust. Both are toxic and high levels in urban environments can cause, or worsen, respiratory problems in humans.
Burning wood emits carbon.
These gases are also responsible for acid rain. Both undergo reactions in the atmosphere that produce strong acids, which dissolve in rainwater. The resulting rain can increase the acidity of soils and lakes, killing sensitive species and can directly damage trees and other plants. It can also damage some stone buildings and monuments.
Another cause for concern is the depletion of the ozone layer, high in the atmosphere. This layer absorbs ultraviolet light, mainly the most harmful forms, minimizing exposure at ground level. The release of chemicals known as chlorofluorocarbons (CFCs), used in aerosol sprays, is blamed for damaging this layer and potentially increasing the exposure of humans, animals and plants to dangerous levels of ultraviolet light. These chemicals were banned in the US and Canada, but many other countries still use them.
CFCs in aerosol sprays are now banned in the United States.
Air pollution can also take the form of tiny particles. Many combustion processes, such as wood and coal fires, wood stoves, and the burning of fuel in cars produce minute particles of carbon, in the form of soot and smoke. These may affect climate, by reducing the transparency of the atmosphere, and by acting as “condensation nuclei,” which encourages water vapor to condense into droplets, increasing cloud cover. At lower levels, these “particulate” pollutants may contribute to respiratory problems in people.
Car emissions contribute to air pollution.
One of the biggest environmental problems facing mankind is due to a pollutant that is not normally directly harmful to humans. Carbon dioxide (CO2) is produced in huge quantities by the burning of fossil fuels, for example by cars, industrial processes, and airplanes. It traps heat in the Earth’s atmosphere, and is the most important “greenhouse” gas. Increased levels resulting from human activities are thought to be raising air and ocean temperatures across the planet, a phenomenon known as “global warming” or “climate change.” This, in turn, seems to be causing melting of glaciers and ice sheets on a large scale, which may lead to rises in sea level and the consequent loss of large areas valuable, low-lying agricultural land, and the displacement of huge numbers of people.
Fertilizer runoff from farms is damaging to aquatic life.
Climate change may also have a drastic effect on agriculture due to changes in temperature and rainfall. Many crop plants may be unable to adapt to drier or wet conditions. Droughts may affect some areas, while others may suffer from flooding, due to increased rainfall. It may be that warming of the oceans will lead to more frequent, and more severe, hurricanes.
This can occur through the release of industrial waste, for example from mining and metal refining activities, into streams and rivers, from where it may make its way into the ocean. A variety of toxic metals can affect aquatic and marine life and may accumulate in the food chain, posing a threat to humans. Another major source of water pollution is fertilizers, which can be washed into rivers and lakes from farmland, causing a phenomenon known as eutrophication. Nitrates and phosphates, present in fertilizers, and essential for plant growth, can also promote uncontrolled multiplication of algae in lakes, causing an “algal bloom.” This reduces water quality and oxygen levels, and may kill fish.
Humans often introduce animal and plant species to areas outside their natural range. Sometimes this is done intentionally and sometimes not, but often it can lead to serious environmental problems. Domestic pets may kill local wildlife, while non-native garden plants may escape and become established in a new area, taking over from native species, perhaps because they have no natural predators in their new environment. Increased international travel means that disease-causing organisms can be easily introduced to new areas, where they may cause devastation among species that have no natural resistance.
Solutions to many of these problems will require action by governments across the globe, for example, to reduce burning of fossil fuels and develop renewable energy resources. Ordinary people, however, can make their own contributions; for example, cutting down on car journeys helps reduce levels of carbon dioxide, nitrogen oxides and soot. Avoiding long haul flights wherever possible may also help. Companies can play a role by using teleconferencing facilities so that employees do not have to travel to meetings, and allow staff to work online from home, where practical. Individuals can also help many small ways, such as minimizing their use of garden fertilizers, not using them when rain is forecast, picking up litter and rubbish that might harm wildlife, and properly disposing of harmful chemicals.