Only forty-some years ago, "climate science" suddenly turned from advancing a theory of global cooling to one of global warming.  A 123-page paper by Christopher Booker, published by the Global Warming Policy Foundation (GWPF), explains this sudden change in terms of a "groupthink" belief system formulated and perpetuated by a few strong personalities.  Through key positions, and with sympathetic lobbyist groups, the theory overwhelmed politics during its formative years in the 1970s from its center in various United Nations agencies until its unraveling began in the late 1990s.

The first of those personalities was Swedish meteorologist Professor Bert Bolin (1925-2007), who believed that increasing atmospheric levels of carbon dioxide from industrialization would inevitably lead to global warming.  Bolin presented his views in 1979 at a first-ever meeting of the "World Climate Conference," sponsored by the World Meteorological Organization (WMO).  The WMO is a 191-member-country agency of the United Nations (U.N.), headquartered in Geneva, Switzerland.

Bolin had developed his theory in the 1950s during thirty-five years of declining temperatures.  Through the 1970s, many scientists, activists, and policymakers had voiced alarm at global cooling.  A common view was that the cooling effect of more dust in the atmosphere, from volcanoes and industrial smokestacks, more than offset the warming effects of carbon dioxide and might require dire policies, such as those proposed by Dr. Arnold Reitze, to include banning the internal combustion engine, regulating industrial research and development, and limiting population.

Six years later, Bolin presented a longer paper for a 1985 conference in Villach, Austria, in which he concluded that "human-induced climate change" called for urgent action at the "highest level."  An attendee who became convinced was Dr. John Houghton, a former professor of atmospheric physics at Oxford, who had been head of the U.K. MET since 1983, was founder of the Hadley Centre in 1990, and would be the lead editor of the first three reports (1990, 1996, and 2001) of the International Panel on Climate Change (IPCC).  The IPCC was established in 1988 by two U.N. agencies, the WMO and the United Nations Environment Program.  UNEP was founded in 1972 by Maurice Strong, its first director, as a result of the U.N. Conference on the Human Environment held in June, 1972. 

Strong was a Canadian self-made billionaire in the energy business, who once self-identified as a "socialist in ideology, a capitalist in methodology."  He became greatly involved in U.N. activities and influenced the Stockholm Conference through a 1971 report he commissioned on "the state of the planet," a summary of the findings of 152 "leading experts from 58 countries."  A December 2015 Breitbart article described Strong as a "totalitarian control freak" for his expressed desire to deny national sovereignty to achieve "global environmental co-operation" through the transformation of the U.N. into a world government.  (Strong later co-founded the Chicago Climate Exchange.)

The IPCC originally represented 34 nations, with Bolin its first chairman and Houghton chairing "Working Group I," charged with contributing the climate change section of a first "assessment report."  Houghton himself wrote the summary of that report, which cited computer models indicating that global temperatures would increase "up to 0.5 degrees Celsius" per decade, despite only a 0.6-degree increase the previous 100 years.  In contrast, the text of the long report was reserved and underscored underlying uncertainty.  The summary was designed to raise concerns, in anticipation of the 1992 "Earth Summit" in Rio, being organized by Strong.  The "summit" added to political momentum and was attended by 108 world leaders, some 20,000 delegates, and an additional roughly 20,000 climate activists.

The only real proof of the scientific theory was computer models, programmed to assume that increasing carbon dioxide was the most important factor driving climate.  One of those who objected to the "predetermined" conclusions of such models was Dr. Richard Lindzen, the Alfred P. Sloan professor of meteorology at the Massachusetts Institute of Technology.  His 1992 paper pointed out that the models ignored other important factors that would have had cooling effects – namely, water vapor, cloud cover, and oceans.  Lindzen also noted that global temperatures had risen in the 1920s and 1930s, when carbon dioxide emissions were comparatively low, but fell back between 1940 and the 1970s, when emissions were rising much more steeply.  He also concluded that the models would have predicted a 20th-century warming four times more than actually recorded.  Some of Lindzen's criticisms are demonstrated in the chart below, from NASA GISS data.  One should note that the GISS frequently "adjusts" its data to be consistent with warming, so the data in the chart do not reflect those available to Lindzen at the time.

Lindzen also focused on how an "illusion of a consensus" had been used to dominate public debate by marginalizing credible scientists who evaluated the same data and disagreed with the prevailing conclusions.  He described how influential interest groups had fervently joined the cause of global warming, such as the Union of Concerned Scientists (UCS), Greenpeace, Friends of the Earth, and the World Wildlife Fund (itself funded by Maurice Strong).  Many of these had formerly lobbied against nuclear weapons during the Cold War, which had just ended.  While the UCS submitted a petition to combat global warming, only "three or four of them, according to Lindzen, were qualified climate scientists."  Frank Press, the president of the National Academy of Sciences (NAS), stated that "overt advocacy ... tended to delegitimize ... independent advice on science and policy."

"Consensus" was furthered with an increase in federal funding for climate research (reference: beginning at 18 minutes in this video) from $240 million annually, in 1989, to $1.5 billion, and to $10 billion over the next twenty years.  The IPCC's 1996 Second Assessment Report attempted to consolidate consensus by 1) introducing verbiage in the summary that had not appeared in a draft report reviewed by authors and 2) deleting 15 key statements that had appeared in the reviewed draft.  Former head of the NAS Frederick Seitz stated in a Wall Street Journal article that he had "never witnessed a more disturbing corruption of the peer-review process ... to deceive policymakers and the public into believing that scientific evidence shows that human activities are causing global warming."  Responsibility lay with the lead author, Ben Santer, associated with the climate Research Unit (CRU) at East Anglia University.

The 1996 controversy was soon overwhelmed by the some-10,000-person Kyoto Conference the following year, a seeming example of consensus designed to continue the political momentum, and later preparation for the 2009 U.N. Climate Change (Copenhagen) Conference.  But the 2009 release of over 1,000 emails and 3,000 other documents from the CRU, known ClimateGate, further revealed the shakiness of climate change theory and resulted in a weak, nonbinding "Copenhagen Accord."

An especially controversial "Climategate" email by Jonathan Overpeck complained that "we have to get rid of the Medieval Warm Period."  A long held conclusion had been that the so-called Medieval Warm Period (c. 950-1250) was much warmer than the modern era, appearing in the IPCC First Assessment report (chart below).

Seemingly on cue, in April 1998, an unknown young Ph.D., Michael Mann, and two colleagues published an article eliminating not only the Medieval Warm Period, but the previous four-century-long "Little Ice Age."  Known as the "hockey stick" graph, it showed an unwavering downward line, until sharply increasing in the late 20th century. When it appeared in the 2001 IPCC Third Assessment Report, Houghton himself appeared in front of a huge blow-up of the "hockey stick" graph to assert that most of the previous 50 years of warming was attributable to human activities.  The hockey stick was meant to be evidence supporting the conclusions of the widely discredited models.

McIntyre and McKitrick (2003) found that the Mann, et. al study 1) showed temperatures only for the northern hemisphere, hence ignoring the rest of the world, and more disturbingly 2) used "proxy" data in the form of tree rings.  "Almost the only tree rings ... which actually had a hockey-stick shape had been one group of bristlecone pines in California."  But Mann's algorithm weighted the California samples 390 times more than samples "from Arkansas, which failed to show a 'hockey stick' shape."  Moreover, 3) in the IPCC report, the temperatures for the last decades of the 20th century were from not tree rings, but thermometer data, spliced onto the tree ring data.  In 2006, a committee of the U.S. Congress commissioned a report by Dr. Edward Wegman, an eminent statistician, that rebuked Mann's methods as well as the wider peer review process.

While the "hockey stick" itself has fallen into scientific disrepute, it still lingers in the public mind, supported by a 2006 National Academy of Sciences report citing seven subsequent studies with similar conclusions.  However, all of those seven studies used "reconstructed" data involving various kinds of proxies (ice cores, tree rings, etc.) and "instrumental" records beginning in 1856, weaknesses found in the Mann, et al. study.  Moreover, many of the authors and participants in these seven studies are the same ones cited in the Wegman report, based on a "network analysis" such that "independent reconstructions are not as independent as one might guess" and that "there was too much reliance on peer review which was not necessarily independent."

Much more is in this timely, informative, and non-technical report from the GWPF, with its credible twenty-five-member scientific Academic Advisory Council, including eighteen having the title of "professor."