Habitat loss  Agriculture  Pollution  Development  Transportation  War

Sulphur dioxide gas is produced when coal and fuel oil are burned. In plants such as broad-leaved plants, sulphur dioxide inhibits growth and can cause cells in the leaves to either collapse or become distorted. Air pollution has wiped out vegetation, and with the plants go all the animals that are dependent on them. Oxides of sulphur and nitrogen that are released into the atmosphere from factories and car exhausts undergo chemical reactions that convert them into nitric and sulfuric acids.

As a result, rain over large parts of North America and Europe are 10 to 1000's times as acidic as rain from unpolluted skies. Once this water reaches rivers and lakes, fish are killed as they cannot survive in such high levels of acidity. Scientists have recently isolated 48 000 lakes that will not be able to sustain life for the next two decades if current trends continue. Snowmelt ponds in upstate New York no longer have Spotted Salamanders living in them as the winter snows are now too acidic.

Offshore oil spills reaching beaches not only have a toxic effect on animals, but also interfere with filtration of water through the sand. Plastic and other forms of litter, caused by dumping at sea, poorly operated refuse dumps and people who carelessly discard things on the beach, increasingly pollute beaches. As many of these articles are not biodegradable, they can cause painful deaths for birds and animals if mistaken for food. In the Northern Pacific Ocean, Laysan albatross have a population of about 400,000 birds in total. There are recorded of birds flying approximately 6 500 km to find food for chicks, and then returning and unable to regurgitate as bits of plastic, namely toothbrushes, are stuck in their throats. Originally albatrosses used to swallow pieces of floating pumice for the fish eggs stuck to them. The albatrosses have now transferred such survival strategies to toothbrushes, bottle caps, nylon netting, toys and floating junk. Another animal that makes mistakes are turtles who think plastic bags are jellyfish and swallow them. The plastic gets stuck in the digestive tract and the animal dies later.

Oil spills wreak havoc on wildlife in the ocean and on the beaches near by. Oil pollution continually threatens penguin population in South Africa, the most recent being in June 2000 off the coast of Cape Town. Due to human error and ill decisions, an unseaworthy bulk ore carrier called Treasure was allowed into Table Bay and once ordered to leave, broke away from the tugs escorting it and sank. Thousands of tons of oil spilled into the ocean, coating thousands of penguins and other coastal birds. Due to a large-scale rescue operation by SANCCOB and public volunteers, many of the penguins were rescued and cleaned. It was unfortunate that South Africans were still recovering and counting the costs of an oil spill that happened four years previously. Another major disaster was when on March 24, 1989, the Exxon Valdez spilled over 11.2 million gallons of oil into waters off the Oregon coastline, coating sea life in petroleum. It remains one of the greatest ecological disasters of all time.

In 1871, a severe problem arose when the flow of the Chicago River in the USA was reserved to carry the city's sewage into the Illinois River system rather than into Lake Michigan, the source of its drinking water. Sewage, because it contains toxins and organic wastes, can overwhelm the decomposing capacity of natural ecosystems. The Illinois River system was destroyed, and along with it the commercial fishing for such species as turtles, mussels and fishes.

Mining and the development of minerals and energy have had many negative effects on habitats through both direct destruction and pollution. Mining can be lethal to the surrounding habitats as many of the waste products produced by mining contain toxic substances. Another problem is that cleaning up water pollution created by mines is extremely difficult.

The construction of dams also creates many ecological difficulties. The construction of the Dickey-Lincoln Dam in the U.S.A had many negative effects on the environment. This hydroelectric project destroyed the habitat of many species including the rare Bald Eagle, Osprey, Bobcat, Lynx, Otter, Moose, Blueback trout and Marten. It also flooded 140 square miles of valuable timber. The construction of high-voltage lines radiating from the dam scarred another 400 square miles of the surrounding landscape.

The building of dams is very expensive in both the short-term and the long-term. Many dams are built in wetland area and often destroy the natural habitat of that area. This is sometimes a strange occurrence as it is often cheaper to maintain the wetlands than to build dams.