Water Pollution

Air Pollution

Habitat Destruction and Species Extinction

Depletion of the Ozone Layer

Ozone is a gas that blocks harmful ultraviolet sunlight. Industrial chemicals released into the atmosphere have caused ozone to break down, opening holes in the ozone layer that tend to concentrate at the poles.

The consequences of continued depletion of the ozone layer would be dramatic. Increased ultraviolet radiation would lead to a growing number of skin cancers and cataracts and also reduce the ability of immune systems to respond to infection. Additionally, growth of the world’s oceanic plankton, the base of most marine food chains, would decline. Plankton contains photosynthetic organisms that break down carbon dioxide. If plankton populations decline, it may lead to increased carbon dioxide levels in the atmosphere and thus to global warming. Recent studies suggest that global warming, in turn, may increase the amount of ozone destroyed.

Plant and animal species are dying out at an unprecedented rate. The leading cause of extinction is habitat destruction, particularly of the world’s richest ecosystems—tropical rain forests and coral reefs. If the world’s rain forests continue to be cut down at the current rate, they may completely disappear by the year 2030.

A significant portion of industry and transportation burns gasoline. When it burns, chemicals and particulate matter are released into the atmosphere. Although a vast number of substances contribute to air pollution, the most common air pollutants contain carbon, sulfur, and nitrogen. These chemicals interact with one another and with ultraviolet radiation in sunlight in dangerous ways.

Smog can usually be found in urban areas with large numbers of automobiles. Smog can cause serious health problems.

Air pollution may cause acid rain. Acid rain has made numerous lakes so acidic that they no longer support fish populations. Acid rain is also responsible for the decline of many forest ecosystems worldwide.

With almost 80 percent of the planet covered by oceans, people have long acted as if those bodies of water could serve as a limitless dumping ground for wastes. However, raw sewage, garbage, and oil spills have begun to overwhelm the diluting capabilities of the oceans, and most coastal waters are now polluted, threatening marine wildlife. Beaches around the world close regularly, often because the surrounding waters contain high levels of bacteria from sewage disposal.

Дата добавления: 2014-12-16