This message of scientific uncertainty has been reinforced by the public relations campaigns of certain corporations with a large stake in the issue.… - Naomi Oreskes

Then-Vice President George H. W. Bush ran for president of the United States pledging to combat the “greenhouse effect with the White House effect”. 1988 was also the year in which the world nations joined together to create the w:Intergovernmental Panel on Climate Change (IPCC) to provide a scientific basis for policy action. Fossil fuel corporations might have begun to take steps to limit the damages their products caused to the global environment.
Instead, leading investor-owned fossil fuel corporations, including ExxonMobil, Shell, and British Petroleum, created the Global Climate Coalition (GCC) to oppose greenhouse gas emission reduction policies. From 1989 to 2002, the GCC led an aggressive lobbying and advertising campaign aimed at achieving these goals by sowing doubt about the integrity of the IPCC and the scientific evidence that heat-trapping emissions from burning fossil fuels drive global warming. They worked successfully to prevent the United States from signing the Kyoto Protocol after it was negotiated in 1997. When the GCC disbanded, they stated that they had achieved their goals....
Between 1988 and 2005, ExxonMobil invested over $16 million in a network of front groups that spread misleading claims about climate science. It also exploited its close relationship with the administration of President George W. Bush to pressure the administration to remove top scientists from leadership roles in the IPCC and the US National Climate Assessment and to promote federal policies driving further reliance on fossil energy

Exxon Mobil misled the public about the state of climate science and its implications. Available documents show a systematic, quantifiable discrepancy between what Exxon Mobil’s scientists and executives discussed about climate change in private and in academic circles, and what it presented to the general public....
In short, Exxon Mobil contributed quietly to climate science and loudly to raising doubts about it. We found that, accounting for reasonable doubt given the state of the science at the time of each document, roughly 80 percent of the company’s academic and internal papers acknowledged that climate change is real and human-caused. But 81 percent of their climate change advertorials in one way or another expressed doubt....
Even while Exxon Mobil scientists were contributing to climate science and writing reports that explained it to their bosses, the company was paying for advertisements that told a very different tale.

As early as 1977, one of Exxon’s senior scientists warned a gathering of oilmen of a “general scientific agreement” that the burning of fossil fuels was influencing the climate. A year later, he had updated his assessment, warning that “present thinking holds that man has a time window of five to 10 years before the need for hard decisions regarding changes in energy strategies might become critical.”...
Exxon chose the path of disinformation, denial and delay. More damagingly, the company set a model for the rest of the industry. More than 30 years ago, Exxon scientists acknowledged in internal company memos that climate change could be catastrophic. Today, scientists who say the exact same thing are ridiculed in the business community and on the editorial page of w:The Wall Street Journal.
We have lost precious time as a result: decades during which we could have built a smart electricity grid, fostered efficiency and renewables and generated thousands of jobs in a cleaner, greener economy. There is still time to prevent the worst disruptions of human-driven climate change, but the challenge is now much greater than it needed to be, in no small part because of the choices that Exxon Mobil made.