Science communicator Bill Nye has cast doubt on the credentials of Mandy Gunasekara, a former top air policy official at the Environmental Protection Agency (EPA). According to a report in The Washington Post, she is set to become the organization’s new chief of staff.

Gunasekara joined the EPA in March 2017, overseeing the agency’s Office of Air and Radiation. During her time in this position, she was involved in attempts to roll back environmental regulations aimed at reducing greenhouse gas emissions and other types of pollution, the Post reported.

She also played a key role in the Trump administration’s withdrawal from the Paris climate agreement. Gunasekara left the EPA last year and set up what she described as a “pro-Trump non-profit” in Jackson, Mississippi, known as the Energy 45 Fund.

According to the non-profit’s website, the organization is “dedicated to informing the public about the environmental and economic gains made under the Trump Administration.”

“President Trump’s bold domestic energy dominance agenda has brought both economic prosperity and cleaner air and water. Energy 45 supports and promotes these policies as well as a broader push towards cooperative federalism,” the website reads.

In her resignation letter from the EPA, Gunasekara wrote “working on your America First agenda for the past two years was the honor of my life,” while praising the administration’s attempts to roll back environmental regulations.

“Historic resistance from Democrats, the media and even some Republicans has made your accomplishments even more monumental,” Gunasekara wrote. “I am increasingly concerned with the rhetoric from the far-left supportive of Venezuelan-style socialism, government take-overs and crony ‘green new deals’ that do little for the environment and threaten our economic success.”

The Post reported that Gunasekara is set to make a return to the agency as chief of staff, according to “two individuals briefed on the matter.”

Appearing on MSNBC’s Hardball with Chris Matthews, Nye said Gunasekara’s environmental policies were “striking” given that she and her husband have two young kids who will “inherit the Earth.” He noted that these children are going to have to interact with their mother, who has been a strong advocate of “putting more carbon dioxide” into the atmosphere.

Nye also questioned appointments that have been made at the EPA over the course of the Trump administration, some of whom, like current administrator Andrew Wheeler—a former coal lobbyist—have ties to the fossil fuel industry.

“What they do—very common in the people that they have hired, the environmental protection agency of late, including Mr. Wheeler—is confuse or try to blur the idea that carbon dioxide, although not a traditional pollutant, is a problem,” Nye said. “Carbon dioxide is the problem. Yes, methane is a problem, some other greenhouse gases are the problem. But because there is so much carbon dioxide, it is the main thing that we need to address.”

Despite the Trump administration’s lack of response when it comes to climate change, Nye said he was “so optimistic about the future.”

“When young people are running the show, all this stuff is gonna change. These people, the Gunasekaras of the world, are going to be throwbacks, they’re not going to be able to stay in business,” he said.

“Article 1, Section 8, Clause 8 of the U.S. Constitution refers to the progress of science and useful arts. We all like to talk about what the Founding Fathers had in mind, well they had science in mind everybody, and carbon dioxide being put into the air by the burning of fossil fuels has been shown to make the world warmer, faster than ever in Earth’s history with the exception of asteroid impacts,” he said. “So we can fix these problems, we can innovate. Clean water, renewable electricity, access to the internet for everybody in the world. That’s what we need.”

In response to a request for comment regarding the reported appointment of Gunasekara and Nye’s commentsthe EPA provided Newsweek with the following statement: “Ryan Jackson is Chief of Staff at EPA until February 21, at which time Michael Molina will serve as Acting Chief of Staff.”

This article was updated to include a statement from the EPA