THE WEEK started with a hopeful sign for those concerned about climate change: Former vice president Al Gore met with Donald Trump for about 90 minutes on Monday, leading some to believe that the president-elect might be ready to accept facts and evidence. By the end of the week, however, Mr. Trump had selected Oklahoma Attorney General Scott Pruitt (R) to lead the Environmental Protection Agency.

Mr. Pruitt wrote this in National Review in May: “Global warming has inspired one of the major policy debates of our time. That debate is far from settled. Scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind. That debate should be encouraged — in classrooms, public forums, and the halls of Congress. It should not be silenced with threats of prosecution. Dissent is not a crime.”

Dissent, indeed, is not a crime, and acknowledging the uncertainties in climate forecasts is reasonable. But rejecting or playing down the near-unanimous warnings of experts, which are based on decades of substantial and continually accumulating evidence and suggest vast implications for future generations, should disqualify a nominee from leading an expert agency charged with making science-based decisions. Among scientists there is virtually no dissent from the conclusion that human activity — the burning of fossil fuels, which releases heat-trapping gases that stay in the atmosphere — is leading to planetary warming, and that the coming changes pose severe risks.

No doubt we would disagree with Mr. Pruitt on any number of issues. He is a leading voice against the Clean Power Plan, President Obama’s centerpiece climate policy. Even before his nomination, the New York Times had uncovered extremely close ties between Mr. Pruitt and the oil and gas industry. He has been tapped to run an agency much of whose work he believes should cease.

We might not oppose Mr. Pruitt’s nomination based on these differences. There are legitimate arguments, based in states’ rights and concerns over overregulation, against the Obama administration’s assertive application of clean water and clean air laws. A president is entitled to advisers, if they are qualified, who reflect his views.

But rejecting settled science strikes us as being in a different category. The Senate should probe Mr. Pruitt’s position on climate change. If he explicitly or implicitly rejects the scientific consensus, that would be justification to vote no. If, on the other hand, he acknowledges the risks facing the globe, lawmakers should ask what Mr. Pruitt would be prepared to do as the nation’s chief environmental officer to combat them.