Environmental careers have grown rapidly since the 1980s, and just about everybody expects that growth to continue for some years. Of course, the reasons behind this success are often disquieting, if not ominous. Ground-level ozone and airborne particles are affecting millions of people throughout the United States. Wildlife habitats continue to be threatened, and around 1,662 plants and animals in the United States alone were considered endangered or threatened as of late 2019, according to the U.S. Fish and Wildlife Service. Hazardous waste still needs to be cleaned up at thousands of Superfund sites. Also periodic contamination, or poisoning, of water supplies by pollutants shows that much work is left to be done to ensure safe drinking water for all.

Fears about such phenomena as global warming, holes in the ozone layer, acid rain, and other environmental crises have many people wondering what the planet will be like in the coming decades for future generations. Public support for environmental work is strong and apparently continues to grow all the time. A 2019 Gallup poll found that 65 percent of respondents think protecting the environment should be given priority over economic development—the widest margin in nearly 20 years.

Environmental careers can be divided into these broad categories: parks and outdoor recreation, air and water quality management, education and communication, hazardous waste management, land and water conservation, fishery and wildlife management, forestry, planning, and solid waste management. What's more, new kinds of jobs are being created all the time to meet new demands. There currently are more than 30 major environment-related areas of study at the college level, and some experts say that we've only begun to see the tip of the iceberg in terms of types of environmental jobs.

Many environmental problems are interconnected and broad ranging. Acid precipitation, often known as acid rain, is caused by pollutants released into the air from cars, trucks, planes, factories, and power plants. When acid rain or acid snow falls, lakes, streams, and oceans are contaminated, causing harm to marine and freshwater life, drinking-water supplies, crops, buildings, and forests. In other words, air pollution can lead to water pollution and to forest destruction. Likewise, forest destruction leads to air and water pollution. These problems further become human problems when they directly affect our health and well-being. This interconnectedness of environmental problems has led to a distinct trend. Environmental professionals increasingly are encouraged to be cross-trained to be able to work on issues involving, for example, both wildlife biology and forestry.

The history of environmental problems is closely linked to two things: the expanding world population and the many advances in technology that began with the Industrial Revolution. When relatively few people inhabited the earth and before they lived in cities, they could afford to pollute their environment with few adverse effects. Trees could be cut for fuel in small enough numbers, and the smoke from widely scattered fires dissipated in the atmosphere. Sewage and garbage could be disposed of without causing disease. Air and water pollution existed, but not in large enough degrees to spark a public outcry or to halt the activities that caused them.

As early as 1300, London, the most heavily populated city in England, was suffering ill effects from the widespread use of coal as a fuel. The air was thick with smoke and smelled bad. In 1306, King Edward I banned coal-burning in London, though the reasons are unclear. Some believe the king was successfully lobbied by the powerful wood establishment to ban coal at a time when England's wood was in short supply, thus keeping wood prices high. Others believe that the king showed remarkable wisdom and foresight in recognizing the harmful effects of air pollution. After a time, however, coal use resumed because there simply wasn't enough wood to fuel the city.

The state of the environment started to deteriorate much more rapidly with the advent of the Industrial Revolution in Europe in the mid-1700s. Large numbers of people living in closely concentrated cities began to produce immense quantities of pollutants with no means of efficiently and harmlessly dispersing them. Great clouds of smoke spewed from factories fueled by coal. By 1750, England had become the first country to be largely powered by coal, but people were so excited by the mechanization of industry and the conveniences that industry and city living afforded, that they pressed full speed ahead without giving much consideration to the damage being done. The mastery of coal, combined with the advent of the steam engine, not only made England the leading industrial nation in the 1800s, but it made it the world's largest polluter as well. Smog engulfed the city, and all manner of wastes were dumped into the Thames River. Later, when these wastes got into the drinking-water supply, thousands of people became ill with typhoid fever. In the 1900s, the situation was worsened by continuing technological developments, including the automobile. In 1952, the sulfur dioxide smog was so severe in London that 4,000 deaths were attributed that year to breathing and respiratory problems caused by pollution.

The United States relied on wood as its primary fuel until 1850, as the amount of wood was abundant and clearing the forests was a major American industry. Coal became the most utilized fuel from about 1885 until about 1950, when oil and gas ended its reign. Although there was no single precipitating event in this country to draw awareness to environmental problems, the biggest contributing factor was probably the net consequence of our reliance on and high consumption of nonrenewable fossil fuels. The environmental movement in the United States was spawned in the 1960s, though its roots were to some extent in the conservationist movement that emerged in the 19th century. By that time, most lakes and rivers in this country had suffered damage, and Lake Erie was actually declared dead, devoid of any plant or animal life. (It has since been revived to some extent.) Air pollution plagued every major U.S. city. And scientists discovered in the mid-1960s that fir and spruce trees in the eastern part of the country were being damaged by something called acid rain.

From the beginning of the Industrial Revolution, some voices have called out for protection, conservation, and care of the environment. Henry David Thoreau was celebrating nature and warning about the encroachment of railroads and industry in the mid-19th century; the Audubon Society and the Sierra Club were formed in the 1890s out of concern that wilderness areas were disappearing; and, in 1903, the National Wildlife Refuge System helped stop the slaughter of waterfowl on Pelican Island, Florida (the birds' feathers were being used for women's hats). The National Park Service was created in 1916 to conserve the national parks' scenic areas and wildlife. Fishery management began in the 1870s and was a busy profession by the 1950s. The first Clean Air Act was passed in 1955, the Air Quality Act in 1967. Rachel Carson's book, Silent Spring, published in 1962, was an urgent statement about the serious health and environmental threats of insecticides. But there was no environmental industry per se until the 1960s; a comparatively few rangers, foresters, public health officials, and advocates essentially made up the environmental field until this time.

However, the watershed year for the U.S. environment movement surely was 1970. In 1970, Americans celebrated the first Earth Day, a nationwide event to promote awareness of the planet's fragility. Earth Day called on consumers and government leaders to clean up the country's messes, to develop alternative and renewable energy resources, and to preserve and take better care of the pristine areas that remained. It raised public awareness and helped fire up environmental action at the grassroots level—that is, citizens began to take action themselves to help the environment. The federal government established first the Council on Environmental Quality and then the Environmental Protection Agency (EPA) to implement environmental legislation. Out of the EPA were born all the state-level EPA organizations, which also work to implement the laws. Since the inception of Earth Day, Congress has enacted more than 40 major federal environmental laws. Today, Earth Day is observed by more than 200 million people worldwide, in more than 140 countries.

The National Environmental Policy Act, which took effect in 1970 as well, required that any federal agency with plans to build, support, or regulate a large facility such as a highway, dam, or power plant first must issue an environmental impact statement (EIS) that would assess any damage the project might cause to the environment. The EIS must also take alternative proposals under consideration. A preliminary EIS is reviewed by federal, state, and local authorities and is made available to the public before the federal agency prepares a final EIS and decides whether to proceed with the project. Sometimes an EIS has resulted in projects being challenged legally and delayed; one well-known example is the Tellico Dam on the Little Tennessee River, which might have eradicated a little-known, endangered species of fish called the snail darter. The project was challenged by 11 lawsuits and held up for several years. It was resumed only after the three-inch-long fish were relocated to other tributaries of the river. The status of the snail darter since has been upgraded from endangered to threatened.

The environmental movement picked up steam in the 1970s. In the 1980s, environmental groups, such as the Sierra Cl