President Obama, followed by science broadcaster Bill Nye, makes his way to Air Force One shortly before departing from Miami International Airport in Miami on April 22. Nye interviewed Obama for a White House video. (Mandel Ngan/AFP/Getty Images)

“Shooting the messenger isn’t going to help you on climate change.”

Bill Nye is talking by phone on an early morning bus ride to Ithaca, N.Y., where his alma mater, Cornell University, is set to celebrate its 150th birthday and he’s scheduled to speak. It has been a busy week — including, most notably, a Wednesday trip with President Obama on Air Force One to visit the Florida Everglades on Earth Day — and Nye is answering the political critics who sniped at the visit.

[Why Obama’s trip to the Florida Everglades is a shrewd move in the climate debate]

When Nye tweeted about the trip, political conservatives made a giant fuss about the amount of energy the trip consumed, and, Nye says, attacked him pretty personally.

“That it uses a lot of fossil fuel for the president to move around is a necessary evil at this time,” Nye responds. “Earth Day is not ‘stay home from work’ day. It’s ‘let’s change the world’ day.”

“Change the world!” is probably Nye’s trademark line — it was written in a 1992 “rules of the road” memo, he says, that he delivered to all incoming staff on the set of the 1990s PBS show “Bill Nye the Science Guy,” telling them modestly what their goals were.

With that TV series, Nye captivated kids with scientific showmanship and humor. In the last few years, though, he has not only recaptured that now-grown-up audience but won an even larger one, with something quite different.

He’s still a jokester — but he’s also become someone who acts a bit like a science gladiator, willing to debate anyone who expressed skepticism about the science of evolution and climate change. He’ll do it on TV — or even at the Creation Museum in Kentucky, where he famously debated creationist leader Ken Ham.


TV’s “Science Guy” Bill Nye speaks during a debate on evolution with Creation Museum head Ken Ham on Feb. 4, 2014, in Petersburg, Ky.  (AP Photo/Dylan Lovan)

In the process, he’s become one of the nation’s leading spokespeople on the climate change issue. “It wasn’t conscious,” Nye say. “I was just playing the hand I was dealt. I take the complicated ideas and make them accessible to everybody.”

There is, admittedly, sometimes a tension involved in Nye’s newer and more politically charged role. His friend and fellow science celebrity Neil deGrasse Tyson declines to debate those who challenge science — sticking more with the role of an educator.

[Opinion: How Tyson’s ‘Cosmos’ brilliantly reconciles science and religion]

Nye feels different. “Bring it on,” he says.

Speaking of debate, Nye has recently changed his stance on the matter of genetically modified foods, which he had criticized in his 2014 book “Undeniable.” “I changed my mind,” he says. “I did more research.”

Nye seems particularly impressed with the high-speed genome sequencing that can be applied to new crop varieties, in order to anticipate what their environmental consequences could be. “You can do a lot to anticipate the knock-on effects of a new gene you introduce,” he says.

His changing stance has enraged some GMO critics — “Is Bill Nye a hired gun for Monsanto?” one recent article asks — but for those worried about the planet, Nye’s climate advocacy surely ought to have him covered.

In one sense, it happened because across multiple TV appearances on outlets like CNN, he gradually shifted from explaining “like wow” science stuff to talking about more charged matters, like a changing climate. But in a deeper sense, Nye has been on the path to becoming this spokesman — at a flying-with-the-president level — for more than 40 years.

It began with the first Earth Day, in 1970, that Nye actually visited in D.C. by bike — with a sign reading “pedals don’t pollute.”

So he was always environmentally conscious but attending Cornell — and taking a class with the famed astronomer Carl Sagan — added the next necessary ingredient. It isn’t widely known, but Sagan was very concerned with human interference with climate — although at that time, it more took the form of an emphasis on the concept of “nuclear winter,” which Sagan used to prominently challenge the Reagan administration’s policies. But Nye says it was closely related to global warming; both drew on computer simulations of how the atmosphere works and how substances like carbon dioxide or sulfate aerosols in the atmosphere affect the planet’s temperature.

Also related were Sagan’s — and NASA scientist James Hansen’s — understanding of the planet Venus and its powerful greenhouse effect. “You can make a pretty strong case that in the modern era, climate change was rediscovered by looking at Venus,” Nye says. Sure enough, Hansen was the man who put the issue on the map by testifying before Congress in the summer of 1988 suggesting that global warming was already underway, thanks to humans.

“When James Hansen testified before Congress in 1988, I said ‘Wow, that’s really something,’” Nye says. “My first kids’ book in 1993, I had a demonstration on climate change.” Several episodes of “Bill Nye the Science Guy” also covered the subject.

“It’s not something that’s really debated in the scientific community,” Nye says. “The connection between humans and climate change is about as strong, or a little stronger, than the connection between cigarettes and cancer.”

Not, of course, that Nye is actually a scientist. He trained as an engineer, and worked at Boeing in that role, before trying out his comedic skills in a Seattle Steve Martin lookalike contest — the beginnings of his comedy career. But he says his engineering background is more than sufficient to make sense of the issue.

“I’m not a full time climate scientist, but I know enough about it to know it’s not something you should be debating or denying. It’s something you should be getting-on-with-it-ing,” he says.

Somewhere along the way, Nye also became one of Obama’s favorite science voices. This week, Nye traveled along to the Everglades as the president sought to instill a newfound appreciation not only of the climate change problem, but also for our national parks system, its value to the economy and even, yes, our place-specific memories.

“If you increase the amount of carbon dioxide, the planet’s going to get warmer,” Nye says. “So the president and I sat and talked about all of this.”

The Everglades, Nye says, are “a one of a kind on the Earth’s surface.”

“So many living things, so much wildlife,” he says. “Oh, and there’s several insects.”

Thanks for reading our new Energy & Environment coverage! You can sign up for our weekly newsletter here and follow our tweets here. Also in Energy & Environment:

The Obama administration is taking on agriculture’s role in climate change. Here’s why that’s a big deal

Are Humpback whales in the clear? Not so fast

New study finds a surprising placebo effect from “environmentally friendly” labeling