In the mid-20th century, the Environmental Movement began growing at an accelerating rate as human misuse of the Earth's environment increased and became more visible to the public. Some of the more important conservation and environmental advocacy related events during the 20th century are shown in a timeline below:
= Beginning in the 1940s the United Nations and its agencies became concerned about the global environment.
= 1951, The Nature Conservancy founded.
= 1950s/60s, in Minamata, Japan, mercury pollution from industrial chemical production contaminates humans and other organisms.
= 1960s, laundry detergents were causing many streams to become covered with foam.
= 1960s/70s, number of bald eagles declined significantly in the United States due to loss of habitat, poaching, and the effects of pesticides.
= 1961, World Wildlife Fund established.
= 1962, Rachel Carson published the book Silent Spring. This book alerted the general public to the dangers of pesticides, particularly the dangers to humans.
= 1963, atmospheric pollution in New York City kills about 300 and injured thousands.
= 1967, people of the world witnessed through television the environmental effects of an oil spill with the wreck of the Torrey Canyon.
= Late 1960s scientists begin to express their concerns about the state of the environment (for example, Paul Ehrlich, Barry Commoner, LaMont Cole, Eugene Odum, Kenneth Watt, Garrett Hardin).
= 1967, Environmental Defense Fund established.
= 1968, Biosphere Conference in Paris examined the condition of the global environment.
= 1968 Garrett Hardin publishes his article The Tragedy of the Commons in the journal Science.
= Early 1970s, scientific evidence suggests that acid precipitation is killing lakes in North America and Europe.
= 1970, first Earth Day was held in the United States on April 22 (also see John McConnell's Earth Site home page).
= 1970, Natural Resources Defense Council founded.
= 1971, Environment Canada established.
= 1971, Founding of Greenpeace.
= 1972, the book Limits to Growth was published. In this book computer models were used to predict the exhaustion of resources and the future state of the Earth's environment. This book suggested that if growth trends in world population, industrialization, pollution, food production, and resource depletion remained as they are, the limits to growth on the Earth will be reached sometime within the next one hundred years.
= 1972, Nixon creates the Environmental Protection Agency in the United States.
= 1972, the United Nations held a conference on the Human Environment in Stockholm. This conference examined the problemsassociated with growth and development. It produced the a number of important global policies.
= 1972, the United Nations created the United Nations Environment Programme.
= 1972, DDT banned in the USA because of its toxic effects of living organisms.
= 1973, OPEC oil embargo demonstrated the necessity for conservation of finite resources such as oil.
= 1973, Cousteau Society established.
= 1977, Love Canal incident taught the public about the dangers of hazardous waste.
= 1979, Three Mile Island nuclear power plant almost had a meltdown.
= 1980, The Global 2000 Report to the President, was submitted in the US.
= 1980, James Lovelock writes Gaia: A New Look at Life on Earth. In this book, Lovelock theorizes that the Earth is a self-regulating entity that maintains optimal conditions for the life that inhabits it. This theory is commonly known as the Gaia Hypothesis. Several scientists have suggested that humans may be changing the state of planet to an extent where life may not be able to return these conditions to their optimum.
= 1980s to 1990s, atmospheric monitoring at Antarctica documented seasonal reductions in stratospheric ozone.
= 1981, Citizen's Clearinghouse for Hazardous Waste founded by Lois Gibbs in response to the problems at Love Canal (now called Centre for Health, Environment and Justice).
= 1983, Julian Simon and Herman Kahn publish The Resourceful Earth: A Response to Global 2000. This book took opposition to the environmental need for reducing population growth and resource use.
= Beginning in 1983, Green Parties are elected in several European Nations.
= 1985, Rainforest Action Network set up to reduce tropical deforestation.
= 1986, Chernobyl Nuclear Power Plant explosion released large amounts of radioactivity into the atmosphere.
= 1986, Rainforest Alliance founded.
= 1987, World Commission on Environment and Development published Our Common Future. This publication introduced the world to the concept of sustainable development.
= 1987, Montreal Protocol was signed by 24 nations to protect the stratospheric ozone layer by cutting back on the emission ofCFC's into the atmosphere. This agreement has been amended three times, in London in 1990, in Copenhagen in 1992 and recently, in Montreal in 1997.
= 1988, James Hansen, from NASA, explains to the United States Congress that global warming due to an enhancement of the Earth's greenhouse effect could disrupt water and food supplies and raise sea levels.
= 1988, Earth Share founded.
= 1989, Exxon Valdez released 11 million gallons of oil into Prince William Sound, Alaska.
= 1990s, closure of numerous fisheries demonstrated the problems associated with resource management.
= 1990, twentieth annual Earth Day was held in 141 countries by an estimated 200 million people.
= 1991, Envirolink is created on the Internet.
= 1992, United Nations Rio Conference held in Brazil.
= 1992, United Nations Framework Convention on Climate Change established agreements between countries dealing withgreenhouse gas emissions and the threat of climate change.
= 1998, Kyoto Protocol was signed by 67 countries. This agreement created a framework for reducing the emission of greenhouse gases into the atmosphere.
= 2002, Johannesburg United National Conference on Sustainable Development. It was here Agenda 21 to Action 21 was discussed in much greater detail.