Bill Nye to Tucker Carlson: Humans Cause '100 Percent' of Climate Change

Bill Nye, a mechanical engineer and "science guy" television personality, appeared on "Tucker Carlson Tonight" Monday evening to discuss climate change. Pushed by Fox host Tucker Carlson on exactly what percentage of climate change is caused by humans, Nye gave a very unscientific answer — 100 percent. He said climate "deniers" suffer "cognitive dissonance," but maybe it is the "science guy" himself who cannot accept that there is reason to doubt climate change.

When Carlson asked, "to what extent is human activity responsible for speeding up [climate change]?" Nye responded, "One hundred percent. Humans are causing it to happen catastrophically fast."

The problem with this answer should be obvious from a scientific perspective. During the show, Carlson acknowledged that the climate is changing, and even that human activity might be contributing to it. But as he explained, "the core question from what I can tell is, why the change? Is it part of the endless cycle of climate change or is human activity causing it?"

If human activity has an impact, then to what degree? Carlson asked, "Is 100 percent of climate change caused by human activity? Is it 23.4 percent? It's settled science, please tell me to what degree human activity is responsible."

Rather than pointing to a specific number, Nye hemmed and hawed. He argued that "instead of happening on timescales of millions of years, or let's say 15,000 years, it's happening on the timescale of decades, and now years." But the self-described "science guy" dodged the fundamental question — to what degree is human action exacerbating climate change? And how can we be sure?

After the host pressed him, Nye finally gave his "100 percent" answer. In most realms of human endeavor, 100 percent is not a serious answer — especially in science, where the simplest movement in physics can be broken down into various factors including air resistance, normal forces, velocity, et cetera.

When Carlson pressed Nye on what the climate would look like today, without human activity, the "science guy" actually provided a rather interesting answer. "The climate would be like it was in 1750, and economics would be that you could not grow wine-worthy grapes in Britain as you can today."

The difficulty with this picture is that it is static. Nye assumed that the climate would not have changed since 1750, during the intermittent "Little Ice Age," when the Earth's climate took a dip. Nye seemed to be thinking that without the increase in carbon emissions caused by human activity, the Earth would be experiencing another ice age today. He did not address how scientists could know this with any certainty, however.

"You don't actually know because it's unknowable," Carlson shot back. Unfortunately, Carlson is much closer to the truth on this. It is not possible to know exactly how the Earth's climate would look today without the Industrial Revolution — and if Nye is correct and we avoided an ice age through global warming, would that be a terrible thing?

In any case, Carlson raised a very important point. "You don't reach correct conclusions in science, or politics, or any other field, unless you can ask for honest answers without being shouted down by people," the host declared.

He opened the segment quoting Nye's recent Facebook Live interview with Vermont Senator Bernie Sanders, in which the science popularizer said that "climate deniers" suffer from cognitive dissonance. The "science guy" sought to explain why people "deny" the "scientific consensus" on climate change: "You have a worldview, and then you have evidence that disagrees with your worldview, so you deny the evidence, and then along with that you deny the authorities that are providing the evidence."

Carlson pointed out that in attempting to "explain away" climate skepticism, Nye was refusing to engage in debate to prove that human action is causing climate change. Instead, he was merely dismissing the other side, refusing to engage in a conversation which could have produced good results.

As Carlson argued, "The essence of science is extreme skepticism. We always ought to be asking ourselves, 'Is our hypothesis true?'"

When it comes to science, very few things can be known with 100 percent certainty. The idea that humans are 100 percent responsible for climate change — and that that is proven beyond a shadow of a doubt — would be laughed at in any scientific paper. So why did the "science guy" say it? Maybe he himself is suffering "cognitive dissonance," when faced with someone questioning his insistence that climate change is "settled science."