Ken Kimmell is the president of the Union of Concerned Scientists, a nonprofit science advocacy organization. The views expressed in this commentary are his own. View more opinion on CNN.

(CNN) When Scott Pruitt stepped down as the Environmental Protection Agency administrator and his deputy Andrew Wheeler took over as acting administrator, many of us in the science advocacy community thought that it couldn't get worse. We hoped that Wheeler would listen to his agency's scientists and alter Pruitt's misguided policies of eliminating science-based policies and rolling back lifesaving climate and public health protections.

The Senate, which will soon vote on whether to confirm Wheeler as EPA administrator, should know this hasn't happened. Instead, Wheeler has continued to advance an agenda focused on undermining safeguards upon which Americans rely to keep their air and water safe.

When I met with Wheeler in October, we talked about the impact of climate change: dangerously high temperatures, rising seas, deadly wildfires, torrential rainfalls and devastating hurricanes. I pressed him to stop the climate policy rollbacks that Pruitt had launched.

I was gravely disappointed to hear him claim that the EPA didn't have the legal authority to do much of anything about carbon pollution from power plants, a departure not only from Supreme Court decisions , but also from the Trump administration's expansive claims of executive power in so many other areas.

Wheeler made it clear he would press ahead in dismantling the two safeguards that lower major sources of US climate change pollution: the Clean Power Plan , which cuts carbon pollution from coal-fired power plants, and the clean car standards , which have already been saving consumers money at the pump. As an additional gift to the oil industry, the EPA is proposing the rollback of safeguards that limit the release of methane pollution , leaving communities near oil and gas facilities at even greater risk of developing serious health issues.

How does Wheeler justify policies that fly in the face of science? He obfuscates. Several months after our meeting, after a US government-led National Climate Assessment was released, he said in a press interview that he had not read the full report to which his own agency scientists had contributed.

Even more disturbing, Wheeler still felt comfortable speculating about the conclusions. The report had, in fact, made clear that the harms caused by climate change will increase exponentially without action. Wheeler again dumbfounded the scientific community when he claimed that future iterations of the report would need to be reviewed by the Trump administration's political appointees.

But Wednesday is a moment of truth, as Wheeler will appear before the Senate committee that will consider his nomination. Lawmakers must grill him about how he has ignored the scientific community's overwhelming consensus on climate change and showcase just how dangerous it is when those in power leave science out of the equation.

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Senators must also focus on Wheeler's recently proposed plan to tilt the playing field against public health and safety protections. He has recommended a new formula for assessing mercury pollution from coal plants (mercury is one of the most toxic pollutants). Under this formula, the EPA can weigh coal plant owners' direct and indirect costs of installing technology to cut mercury pollution, but cannot look at all the protections' benefits to the public.

More specifically, if a pollution control technology reduces mercury pollution and also other dangerous air pollutants, such as soot, the EPA can only consider the value of lives saved and health care costs reduced due to mercury reductions -- and must ignore the benefits of reducing soot. Putting this blinder on makes no sense, but counting all the benefits of this safeguard makes it harder to roll back the protection, which is what the coal industry -- Wheeler's former client -- wants.

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