Famed environmental journalist and activist Bill McKibben urged a crowd of over 250 students Tuesday night to support a reduction in fossil fuel emissions to stem global warming.

At a Yale Political Union debate, titled “Resolved: Divest from Fossil Fuels,” McKibben argued that society must find ways to restrict corporations from emitting fossil fuels without facing appropriate repercussions. McKibben has authored several books on curbing climate change, including “The End of Nature,” which was considered the first book related to global warming when it was published in 1989.

“We need to figure out ways to take away the social license of the fossil fuel industry,” he said. “Companies investing in fossil fuels are investing in the richest industry on the planet, so it won’t be easy … [These companies] have become an outlaw force, an outlaw against the laws of physics and chemistry.”

While different YPU parties took opposing stances on how to best combat global warming, McKibben stressed that there should be “no particular partisan cast to these ideas.” McKibben said he thinks everyone has a stake in this problem, adding that the issue should excite students’ moral sympathies and their instincts for self-preservation.

“This is between human beings on the one side and chemistry and physics on the other,” he said.

To encourage students to take action, McKibben discussed an organization he spearheaded four year ago called “350.org,” which has advocated for reduced emissions in 188 countries across the globe. The group has held roughly 20,000 demonstrations thus far, McKibben said, and the organization will launch a campaign this November to “speak truth” about the fossil fuel industry’s power.

Jeremy Weltmer ’13, former YPU floor leader of the right, led the opposition side, arguing that the companies responsible for much of fossil fuel emissions are also investing heavily in clean energy alternatives, so they deserve continued support rather than divestment.

McKibben refuted Weltmer with reference to the fact that BP sold all of its divisions in solar power two years ago.

Responding to a question about how college activism could affect change in the fossil fuel industry, McKibben said he believes Yale students have the ability to argue persuasively for fossil fuel reductions. With the correct mix of politeness and confrontation, he said, Yale students could make an impact alongside fellow college students around the country.

Five audience members praised McKibben’s clarity and conciseness, as well his ability to simplify a complicated topic.

Amalia Halikias ’15, a member of the Independent Party, said she thought the debate was incredibly informative, as she previously knew very little about the scope of fossil fuels’ impact on global warming.

Josh Revesz ’13 said he agreed with most of McKibben’s stance and was not convinced by Weltmer’s argument because oil companies would reduce their profit margins by developing clean energy technologies. Party of the Left member Stephen Marsh ’13, who gave a speech supporting McKibben’s position, said he thought McKibben provided a strong moral case. He added that while he thought speakers on the opposing side also gave well-presented speeches, he found some hard to believe because their logic was circular.

Pleased by the large student turnout, Harry Graver ’14, speaker of the YPU, said he thought the debate was a success.

“Bill McKibben was engaging, understandable, and I liked that he did not focus on the hard science parts of the global warming debate,” said Graver, also a staff columnist for the News. “Everyone I think left with questions to ask themselves on how their feelings on the issue have changed.”

McKibben graduated in 1982 from Harvard, where he was president of the Harvard Crimson newspaper.

Correction: Sept. 28

A previous version of this article said Yale Political Union guest speaker Bill McKibben argued that energy company BP divested its interests in solar and wind power two years ago. However, BP maintains investments in wind farms across the United States.