Discovery of carbon dioxide accumulation in the atmosphere, 1957 - Roger Revelle and Charles Keeling of Scripps Institution of Oceanography began documenting rise of CO2 from 315 parts per million (ppm) base that year. Revell writes: "Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future." Ice core studies later show that CO2 levels were at 280 ppm in the latter 19th century. CO2 level by the year 2010 is around 385 ppm. First predicted in 1896 by Swedish chemist Svante August Arrhenius, the alarming implications of CO2 accumulation began to be appreciated in the 1970s, and led to an international effort to study and understand climate change in the 21st century. (See Spencer Weart's Discovery of Global Warming, Harvard University Press, 2008.)
Publication of Silent Spring by Rachel Carson, Sept. 27, 1962 -- The book that catalyzed the worldwide environmental movement, Silent Spring called for an end to indiscriminate pesticide use and, on a broader level, a change in the way we view nature. Carson, as both a scientist and gifted writer, was uniquely qualified to warn about the long-term impacts of man's attempts to control nature through technology. The reaction to her book was highly polarized. Even before its publication, Silent Spring had turned into a "noisy summer," as the New York Times said that year, with the chemical industry "up in arms" about the book. One critic said the book implied a "return to the Dark Ages, and the insects and diseases and vermin would once again inherit the earth." Yet the book never advocated a complete ban on pesticides, only a more cautious approach to the link between human health and the environment. In one memorable passage, Carson wrote: "If the Bill of Rights contains no guarantee that a citizen shall be secure against lethal poisons distributed either by private individuals or by public officials, it is surely only because our forefathers, despite their considerable wisdom and foresight, could conceive of no such problem." (See Silent Spring Wikipedia article)
Discovery of atmospheric ozone depleting chemicals, 1974 -- F. Sherwood Rowland and Mario J. Molina describe the way refrigerants (CFCs or chlorofluorocarbons) break up ozone in a catalytic cycle in the June issue of Nature. Rowland and Molina win the Nobel Prize for chemistry in 1995 along with German atmospheric scientist Paul J. Crutzen. The discovery leads to an international effort to understand and then mitigate the impacts of CFCs in the Montreal Protocol of 1987, strongly backed by US President Ronald Reagan. The ability of international agencies to deal with this environmental issue has been seen as a hopeful development for better world cooperation in enviornmental protection. (See the Nobel Prize page; also EPA pages about the Montreal Protocol ).
1712 -- Bernardo Ramazzini (1633 - 1714), the father of occupational medicine, publishes De Morbis Artificum Diatriba (English title, printed in 1764 was The Diseases of Artificers, which by their particular callings they are most liable to, with the Method of avoiding them, and their Cure).
1773 -- William Bartram (1739-1823) American naturalist sets out on a five year journey through the US Southeast to describe wildlife and wilderness from Florida to the Mississippi. His book, Travels, is published in 1791 and becomes one of the early literary classics of the new United States of America. See the Travels of William Bartram web site.
1824 -- Jean Baptiste Joseph Fourier writes "Remarks on the Temperature of the Terrestrial Globe and Planetary Spaces" for Annales de chimie et de physique in which he proposes the theory that the sun's heat is partially trapped in the earth's atmosphere like a giant glass jar -- the first scientific reference to global warming.
1845- 1847 The first two volumes of the Kosmos published by Alexander Von Humboldt, German explorer and pioneering geographer for whom the Humboldt current is named. Von Humbolt observed in 1819 that the fluctuating levels of a Venezuelan lake were related to deforestation in the surrounding hills. "By felling the trees that cover the tops and sides of mountains, men in every climate prepare at once two calamities for future generations: the want of fuel and the scarcity of water... When forests are destroyed ... the beds of rivers, remaining dry during part of the year, are converted into torrents whenever great rain falls on the heights... "
1859 -- Charles Darwin's book On the Origin of Species is published, in which competition is seen as a mechanism for natural selection and survival of species. Alfred Russel Wallace independently came up with the same theory and spurred publication of the book.
1863 -- Thomas H. Huxley (a friend and defender of Charles Darwin) says "The question of questions for mankind – the problem which underlies all others" – was to ascertain "the place which Man occupies in nature ... What are the limits of our power over nature, and of nature's power over us?"
1864 -- George Perkins Marsh writes Man and Nature: The Earth as Modified by Human Action, with emphasis on forest preservation and soil and water conservation. Along with Alexander von Humboldt (1769 - 1859) and Ernst Haeckel (1834-1919), Marsh is considered a founder of environmental science and the scientifically-based conservation movement.
1866 -- The term "ecology" is coined (in German as škologie by Ernst Heinrich Philipp August Haeckel (1834-1919) in his Generelle Morphologie der Organismen. Haeckel was an anatomist, zoologist, and field naturalist appointed professor of zoology at the Zoological Institute, Jena, in 1865. Ecology is from the Greek oikos, meaning house or dwelling and logos, meaning discourse or study of a thing.
1875 -- Austrian geologist Eduard Suess proposes the term biosphere for the conditions promoting life on Earth including flora, fauna, minerals, matter cycles, et cetera.
1878 -- Alfred Russel Wallace, who independently theorized natural selection, publishes Tropical Nature and Other Essays in which he warned about the dangers of deforestation and soil erosion. Wallace also publishes Island Life in 1880 in which he proposed theories of biogeography.
1926 -- Vladimir I. Vernadsky, a Russian/French geologist, publishes "The Biosphere" describing principles of the biogeochemical cycles.
1936 -- Arthur G. Tansley coins the term "ecosystem"
1943 -- Jacques Cousteau develops the self-contained underwater breathing aparatus (scuba) which makes extended underwater exploration possible. Cousteau's 1953 book, The Silent World sells more than 5 million copies. His film by the same name wins an Academy Award for best documentary in 1957, the first of three such awards that his films would earn.
1957 -- 1958 -- International Geophysical Year is a global scientific effort to understand the earth and a major step forward for international understanding. It was modeled on the International Polar Years of 1882-1883 and 1932-1933 and was intended to allow scientists from around the world to take part in a series of coordinated observations of geophysical phenomena, according to a National Academy of Sciences history. Some 67 countries are involved.
1957 -- Discovery of carbon dioxide accumulation in the atmosphere by Roger Revelle and Charles Keeling as part of the International Geophysical Year.
1959 -- Jane Goodall begins to live among and observe wild great apes. Goodall's observations of wild chimpanzees, Dian Fossey's observations of wild gorillas, and Berute Galdikas' observations of wild orangutans substantially revised human perception of our closest relatives. Fossey was murdered in 1985. Goodall and Galdikas continue as advocates for animals of all species.
1962 -- Publication of the book Silent Spring by Rachel Carson
1970 -- The Gaia theory is proposed by James Lovelock advocating the view that the Earth can be seen as a single living macro-organism.
1974 -- Discovery of atmospheric ozone depleting chemicals by F. Sherwood Rowland and Mario J. Molina
1990 -- Intergovernmental Panel on Climate Change issues its first report, serving as the basis of the United Nations Framework Convention on Climate Change (UNFCCC).
1996 --Lead poisoning is linked to anti-social behavior in a study by Dr. Herbert Needleman, a psychiatrist at the University of Pittsburgh Medical Center. The study is published in the Journal of the American Medical Association and caps a long line of studies about physical and behavioral problems caused by leaded gasoline and lead paint.
21st century -- Observations by thousands of scientists working in the Arctic and Antarctic confirm that accelerated warming is taking place, and that polar ice caps are rapidly shrinking, as a direct result of the accumulation of fossil fuel byproducts in the atmosphere.