Bill Nye says President Donald Trump’s anti-science policies could have devastating ramifications for the environment and humanity.

The celebrity scientist railed against Trump administration climate change skeptics Monday during a Facebook Live interview with Sen. Bernie Sanders (I-Vt.), an outspoken advocate for climate action and renewable energy development.

“The longterm implications are potentially catastrophic,” Nye told the 2016 presidential candidate. “The problem is the speed at which the world is warming. It’s not that the climate is changing ― it’s the rate.”

Nye, best known for hosting the popular ‘90s children’s television show “Bill Nye the Science Guy” and the upcoming Netflix series “Bill Nye Saves the World,” went on to explain the damaging consequences of ignoring climate change.

“Half the people in the world live near coastlines. As the ocean gets a tiny bit warmer, it gets a tiny bit bigger. But the ocean is big and a tiny bit is huge,” Nye said, referencing scientific reports that show rising sea levels caused by climate change could engulf many major cities.

Sanders, who holds positions on the Senate’s energy and environmental committees, hosted the live stream on his Facebook page to help viewers better understand the “global crisis of our time.”

Today I'm sitting down with Bill Nye to talk about climate change. This is the global crisis of our time, and it is important for everyone to understand what is happening, why it is happening, and what we can do about it. Watch at Facebook.com/senatorsanders A post shared by Bernie Sanders (@berniesanders) on Feb 27, 2017 at 7:53am PST

Trump, who once called global warming a hoax “created by and for the Chinese,” has pledged to “cancel” the 2015 Paris Agreement, a landmark global accord that more than 100 nations have signed to reduce carbon emissions and prevent dangerous increases in global temperatures. The president is also promising to revive America’s coal industry instead of focusing on developing cleaner renewable energy.

Climate change skeptics pepper the Trump administration, including new Environmental Protection Agency head Scott Pruitt, who sued the agency 14 times during his tenure as Oklahoma attorney general. He’s also vowed to roll back some of former President Barack Obama’s most progressive initiatives to combat climate change.

Nye is baffled by government officials who deny humans’ impact on the earth’s rapidly warming temperature and changing climate, despite conclusions drawn by 97 percent of climate scientists.

“The science is settled, everybody,” Nye said. “There’s overwhelming proof. Proof isn’t the word. There’s overwhelming evidence.”

Nye also took a dig at conservative news outlet Fox News during his Q&A with Sanders.

“The one thing that really is hard for me about Fox News is the denial of climate change and science,” Nye said. “Many of the other things they assert are troubling, but that one is the one that just crosses the line for me.”

Facebook Sen. Bernie Sanders (I-Vt.) asks Bill Nye questions about climate change during a Facebook Live interview Monday.

Still, Nye remains hopeful. He said that Trump’s tendency to contradict himself (see: his relationship with Russia President Vladimir Putin, his opinion of the electoral college, etc.) could be a signal he might also change his position on climate change in the future.

“We can solve this problem, everyone,” Nye said. “It is reasonable to me that if we can show an economic benefit to turning things around, we could turn things around. ... I think if we can get these people to just look at the world a little differently they will be on the side of domestically produced renewable electricity.”

Trump claims wind power, an increasingly popular source of renewable energy, “kills all the birds” and is “ugly.” But Nye refuted the president’s assertions, pointing to coal-fired electricity plants as much more deadly for birds.

“If you want to kill birds, fossil fuels are terrific,” he joked.

Not only is investing in renewable energy, such as wind and solar power, good for the environment, but it would boost U.S. job creation, Nye said.

“Even if the wind turbine blades are designed in Sweden or Finland or Denmark, you have to put them up, you have to erect the turbines here,” Nye told Sanders. “There’s a huge [economic] opportunity.”

How will Trump’s first 100 days impact you? Sign up for our weekly newsletter and get breaking updates on Trump’s presidency by messaging us here.