Beginning in 1950, spectrography showed that carbon dioxide (CO2) and water vapor lines did not overlap completely. At that same time, climatologists also realized that little water vapor was present in the upper atmosphere. Both events illustrated that the CO2 greenhouse effect would not be overwhelmed by water vapor, leaving environmental scientists with the realization that CO2 was building in the atmosphere. This issue led to the further realization that global climates were warming within a “greenhouse” effect created by that CO2. While scientists have come to agreement over the climate change issues over the past half century, corporations within the U.S. had a great deal of influence over the halting of any consensus. Now, more than ever, it seems apparent that global warming is occurring and that the U.S. continues to remain in denial about this issue. Understanding the history of climate change will provide a solid foundation before you get your degree.

1950 – 1970

Scientists began to experiment with various climate change models. Perhaps one of the first experiments that confused the public regarding environmental warming vs. cooling was the one Maurice Ewing and William L. Donn offered in 1958. The Ewing-Donn theory holds that the barrier standing between then-current populations and another Ice Age was a steadily thinning layer of about six feet of ice covering the Arctic Ocean. Should it melt completely, the birthplace of glaciers would be reopened. The weight of evidence from both American and Russian scientists is that the Arctic is warming appreciably. This could mean that all the conditions which led to the four ice-cycles of the last million years are still in operation.

In that same period of time, between 1957 and 1958, the noted International Geophysical Year brought new funding and coordination to climate studies. During that year, Roger Revelle discovered that CO2 produced by humans will not be readily absorbed by the oceans, a landmark opening salvo that destroyed a long-term standing that the immense mass of the oceans would quickly absorb whatever excess carbon dioxide might come from human activities.

In the 1960s, attention turned to historic temperature changes. Although temperatures had been rising since the late 19th century, J. Murray Mitchell, Jr. of the U.S. Weather Bureau’s Office of Climatology reported a downturn of global temperatures since the early 1940s. However, he also acknowledged random variations from place to place and year to year.

Charles David Keeling accurately measured CO2 in the earth’s atmosphere and detected an unusual rise. The Keeling Curve is still used to measure the progressive buildup of CO2 in the atmosphere. The level was 315 ppm and the mean global temperature (five-year average) was 13.9 degrees centigrade. As of October 2014, the CO2 level is 395.93 ppm. 2014 is on pace to be the warmest year on record since records began in 1880.

From 1965 to 1970, scientists became more aware of the small changes that could alter climate. The first meeting on causes of climate change met in Boulder Colorado in 1965, and it was here that scientists pointed to the chaotic nature of the climate systme and the possibility of sudden shifts. The International Global Atmospheric Research Program was launched in 1967, mainly to gather data for better short-range weather prediction, including climate. Syukuro Manabe and R.T. Wetherald [PDF] made a convincing calculation that doubling CO2 would raise world temperatures a couple of degrees.

For the first time in 1968, studies suggested the possibility that the Antarctic ice sheets [PDF] could collapse, raising sea levels catastrophically.

1970-1990

The global environmental movement becomes stronger, and the celebration of the first Earth Day occurred in 1970. That same year, the U.S. National Oceanic and Atmospheric Administration (NOAA) was created as the world’s leading funder of climate research. More organized research efforts were underway, and public awareness increased, thanks to drastic weather changes across the globe. Some highlights include:

1976: Studies show that chlorofluorocarbon (CFCs), methane, and ozone can make a serious contribution to the greenhouse effect. Deforestation and other ecosystem changes are recognized as major factors in the future of the climate.

1977: Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in next century.

1978: Attempts to coordinate climate research in US end with an inadequate National Climate Program Act, accompanied by rapid but temporary growth in funding.

1979: World Climate Research Programme launched to coordinate international research.

1980: Reagan’s election brings backlash against environmental movement. Political conservatism is linked to skepticism about global warming.

1981: Warmest year on record to date.

1982: Greenland ice cores reveal drastic temperature oscillations in the space of a century in the distant past.

1985: Villach Conference declares consensus among experts that some global warming seems inevitable, calls on governments to consider international agreements to restrict emissions. Wally Broecker begins to speculate that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change.

1987: Montreal Protocol of the Vienna Convention imposes international restrictions on emission of ozone-destroying gases.

1988: Toronto conference calls for strict, specific limits on greenhouse gas emissions; UK Prime Minister Thatcher is first major leader to call for action. Intergovernmental Panel on Climate Change (IPCC) is established.

1989: Fossil-fuel and other U.S. industries form Global Climate Coalition to tell politicians and the public that climate science is too uncertain to justify action. This coalition dies in 2002 after a major scientific report on the severity of global warming by the IPCC in 2001, leading to large-scale membership loss.

1990 – 2000

Global warming skeptics come to the forefront, and U.S. corporations continue their war against news about climate change. In 1990, the IPCC begins to report on a regular basis with dire news, and the breakup of Antarctic ice shelves begin to affect public opinion. Some highlights include:

1991: Global warming skeptics claim that 20th-century temperature changes followed from solar influences, although the solar-climate correlation is debunked in the following decade.

1992: Conference in Rio de Janeiro produces United Nations Framework Convention on Climate Change, but the U.S. blocks calls for serious action.

1993: Greenland ice cores suggest that great climate changes can occur in the space of a single decade at least on a regional scale. This study was upscaled in 2008 to show that each climate change was accompanied by a massive reorganization of atmospheric circulation.

1995: Second IPCC report detects “signature” of human-caused greenhouse effect warming, and declares that serious warming is likely in the coming century. Reports of the Antarctic ice shelves breaking up and other signs of actual current warming in polar regions begins.

1997: International conference produces Kyoto Protocol, setting targets for industrialized nations to reduce greenhouse gas emissions if enough nations sign onto a treaty. The U.S. Senate rejected this effort in advance.

2000 — Now (2012)

Despite the dissolving of the Global Climate Coalition, the oil lobby convinces the U.S. administration that the global warming problem does not exist. A meeting in Bonn included the end of a debate about climate change and global warming among all but a few scientists, and most countries outside the U.S. develop mechanisms toward Kyoto agreement targets.