(Update: Adding comment from Heartland Institute)

A conservative think tank that does not believe in human-induced climate change has been sending to tens of thousands of K-12 and college science teachers materials that reject basic principles on which nearly all climate scientists agree — and now, some U.S. senators are asking Education Secretary Betsy DeVos whether staff members in her department have anything to do with it.

The Education Department did not  respond to a query about the letter sent by Democratic Sens. Sheldon Whitehouse of Rhode Island, Brian Schatz of Hawaii, Elizabeth Warren of Massachusetts and Edward J. Markey of Massachusetts. The reason the senators are asking, they said, is because DeVos issued a statement last week — her first about any non-education-related White House actions — in support of President Trump’s decision to pull the United States out of the landmark Paris climate agreement (which all countries had signed except Syria and Nicaragua). The Michigan billionaire said in her statement:

“The announcement made today by the President is one more example of his commitment to rolling back the unrealistic and overreaching regulatory actions by the previous Administration. President Trump is making good on his promise to put America and American workers first.”

Shortly after she issued the statement, DeVos was asked by reporters whether she believes in human-caused climate change. She responded, “Certainly, the climate changes. Yes.” Then, asked what should be done about it, she responded: “I don’t have any answer. I’m here to talk about students in schools today.”

The senators reacted with a letter that accuses DeVos of having done a “quick about-face” from statements she had made in her February confirmation hearing before the Senate.

In their letter, the senators said in part:

It is our sincere hope that neither White House staff nor Department of Education officials have turned to the Heartland Institute on the issues of climate change and climate science, or had any roll in this mailing to educators. At your nomination hearing, you were asked whether you would stand on the side of students or with the political entities trying to force junk science into schools. You responded that you ‘support the teaching of great science and especially science that allows students to exercise critical thinking and to really discover and examine in new ways.’ We agree that ‘great science’ and critical thinking are cornerstones of a high-quality education, but that is not achieved with Heartland’s industry-funded and possibly fraudulent materials.

Heartland sent to teachers materials that include a DVD, pamphlets and a book titled “Why Scientists Disagree About Global Warming,” which question the scientific consensus among climate researchers that human activity is fueling climate change.

Trump has said in the past that climate change is a hoax, and Trump spokesman Sean Spicer said recently that he hadn’t asked the president about the subject and couldn’t clarify Trump’s position. Scott Pruitt, administrator of the Environmental Protection Agency, also refused to discuss Trump’s views on climate change.

The nonprofit National Center for Science Education said most science teachers understand the scientific consensus on climate change, according to a national study conducted in 2014-2015 by the center and Pennsylvania State University researchers. But, it said, about three in 10 middle and high school science teachers “reported telling their students, wrongly, that the causes of recent climate change are the matter of scientific debate.”

In a piece on the Heartland website, Joseph Bast, president and chief executive officer of the institute, criticized the senators, saying it was “despicable” that they would “lie” in an open letter about the institute’s funding and other issues. “Shame, shame, shame,” it said. It also said in part:

Happily, it now appears our work is informing the decisions of the Trump administration, conscientious members of the U.S. House and Senate, and governors and state elected officials from coast to coast. I understand this is bad for you, but it is good for the nation, for the environment, and for us.

Here is the letter to DeVos from the four senators; below that is a letter that Sen. Whitehouse had sent out earlier to science teachers and their organizations: