Environmentalism or environmental rights is a broad philosophy, ideology and social movement regarding concerns for environmental protection and improvement of the health of the environment. Environmental movements are all the activities and organizations involved in protecting the environmental, including those involved in climate and nature protection, as often also promoting sustainable energy and animal protection.

Such organizations were already active at the end of the 19th century, but it really took off after WWII and especially about 1970. AS environmentalism advocates the preservation, restoration and improvement of the natural environment and earth system elements or processes such as climate, to control pollution or protect the animal diversity. While air pollution was clearly visible in the Great Smog in 1952, which killed thousands in London, this is much less true of structural air pollution, that may have claimed the life of between 25 and 40 million people in the 20th century. A broad social movement, including the student movement, women's movement and the peace movement, was founded. Environmentalism is often represented by the color green.

The origins of smoke pollution lay in the atmosphere during the Industrial Revolution. Great factories emerged everywhere in the western world. After identifying the environmental degradation and pollution, the highest priority went to water and air pollution. The Public Health Act 1875 required all furnaces and fireplaces to consume their own smoke. It was only after the Great Smog of 1952 that the Clean Air Act 1956 was passed and airborne pollution in the city was tackled.

Due to the international nature of the problem, the major economic interest, scientific uncertainties and the effects not always immediately visible, it proved difficult to get progress. Climate change and the decline of biodiversity are hard to handle. These problems have far-reaching consequences for humankind.

Ideas inspired various environmental groups around the globe to establish protest groups to campaign for greater protection for animals, and began measures of nature conservation. In the 20th century, environmental ideas continued to grow in popularity and recognition. Efforts were starting to be made to save some wildlife. For example, during the 1930s Nazis had elements that were supportive of animal rights, zoos and wildlife. They took several measures to ensure their protection.

After the Second World War throughout the 1950 and beyond the 1970s, photography was used to enhance the public awareness of the need for protecting land and recruiting members to environmental organizations. After a focus on preserving wilderness in the 1950s and 1960s, focus was broadened to include issues as air and water pollution. Environmentalism continued to evolve to face up to new issues as global warming, overpopulation, genetic engineering and plastic pollution.

In 1962, the environmental impacts of spraying DDT was questioned by not understanding the effects on human health and ecology. It was suggested that DDT and other pesticides may cause cancer. The resulting public concern led to the creation of the United States Environmental Protection Agency in 1970, which banned the agricultural use of DDT in 1972. Environmental interest grew. New pressure groups formed, e.g. Greenpeace. The creation of Earth Day, the first day of spring, 1970, was another milestone in the movement. Earth Day is now (2021) a globally celebrated day in 192 countries.

The UN’s first major conference was held in 1972 as the United Nations Conference on the Human Environment. It was a major turning point in the development of international environmental politics. Research demonstrates a precipitous decline in the US public’s interest in different areas of environmental concern. Americans are less likely be actively participating in such movement or organization and more likely to identify as unsympathetic to environmental movements than in 2000. The lingering factor of the great Recession of 2008 is likely the cause. A survey of the National Geographic indicates a strong desire for commitment, indicating a majority were in favor of more than half of the Earth’s land surface protected.