The key phrases in Pruitt’s testimony are “in some manner” and “with precision.” These allow Pruitt to acknowledge climate change is happening while moving uncertainty downstream, into the “details.”

This rhetoric is out of step with the latest science. The most recent IPCC report expresses 95 percent confidence that humans are the main cause of most global warming observed since the 1950s. According to one paper summarized on NASA’s Global Climate Change website, “97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are extremely likely due to human activities.” The list of scientists and agencies in agreement goes on and on.

Some conservatives have introduced uncertainty by suggesting climate change might be driven by “natural” global cycles. But according to Maureen Raymo of Columbia University’s Lamont-Doherty Earth Observatory, we know why climate changes naturally, and non-human activity can’t explain the rapid changes observed in the past century. “The Ice Ages happen due to subtle changes in the sun-earth distance that unfold over thousands of years, and which can lead to sometimes rapid climate change, when thresholds are crossed.” These cycles are still happening, but “the same factors that cause these huge Ice Age swings could not possibly be invoked to explain the warming we now see.” In fact, Raymo said, “left to its own devices, right now Mother Nature would be making the climate colder.”

The planet has warmed by about 2 degrees Fahrenheit since the 19th century. “You can quibble about tiny bits,” said Raymo, “but the vast majority of what we observe is that it’s because we’ve been combusting fossil fuels.”

As Gavin Schmidt, Director of the Goddard Institute for Space Studies and Principal Investigator for the GISS ModelE Earth System Model, put it, “In science, nothing is ever known perfectly. Is there remaining uncertainty in the exact value of gravity? Yes. But to something like the fourth decimal place. It doesn’t matter. So the question is: Is the remaining uncertainty relevant to any policy decision anyone would want to make? And the answer is: no.”

Uncertainty has proved a reliable tool to manipulate public perception of climate change and stall political action. In 2015, the Union of Concerned Scientists released The Climate Deception Dossiers, which describes a 1998 memo from the American Petroleum Institute that, according to the dossiers, “mapped out a multifaceted deception strategy for the fossil-fuel industry that continues to this day—outlining plans to reach the media, the public, and policy makers with a message emphasizing ‘uncertainties’ in climate science.” The UCS authors write that the memo (included in the report) states “victory” would be achieved “when ‘average citizens’ and the media were convinced of uncertainties in climate science despite overwhelming evidence of the impact of human-caused global warming and nearly unanimous agreement about it in the scientific community.”