Scientists are divided on whether human-caused climate change is real or significant.

By 2001, the scientific evidence for human-caused climate change had been accumulating for decades. The Intergovernmental Panel on Climate Change, established in 1988, had published two major assessment reports, each more confident than the last. The Third Assessment Report, released in 2001, stated that evidence for warming was ‘unequivocal’ and that ‘most of the observed warming over the last 50 years is likely due to increases in greenhouse gas concentrations.’ This was the consensus of thousands of scientists across more than a hundred countries.

In March 2001, the Bush administration announced it would not ratify the Kyoto Protocol. The White House Council on Environmental Quality, headed by former petroleum industry lobbyist Philip Cooney, began editing government scientific reports to insert uncertainty language that the scientists who wrote them had not included. A 2002 White House communications memo advised the administration to emphasize that climate science was ‘uncertain’ and to call for more research rather than action. These edits were not public at the time; they were exposed in 2005 when internal documents showed Cooney’s handwritten changes to EPA and IPCC summaries. He resigned and immediately took a job at ExxonMobil.

The manufactured doubt was reinforced by a network of think tanks, the Global Climate Coalition, the Competitive Enterprise Institute, the Heartland Institute, funded substantially by fossil fuel companies and coordinating messaging designed to cast the science as unsettled. Their target audience was not scientists, who already had the data, but journalists, legislators, and the general public. The strategy was documented later in internal industry communications and closely resembled the campaign the tobacco industry had run decades earlier to delay action on smoking.

For students in school in the early 2000s, the result was that climate science was frequently presented as genuinely controversial. Some states required ‘balance’ in how climate change was taught; some teachers, uncertain themselves, presented the question as still open. A student graduating in 2003 might reasonably have concluded from their coursework that scientists were divided on whether human-caused climate change was real, not because that was what the science said, but because powerful interests had successfully inserted that impression into the educational environment.