Journalist, social activist and bestselling author Naomi Klein addressed a packed house at the University of Colorado Boulder Thursday about the battle between capitalism and climate change.

The university’s Cultural Events Board and student divestment group Fossil Free CU brought Klein, author of “The Shock Doctrine” and “No Logo,” to talk about her latest book, “This Changes Everything: Capitalism vs. the Climate.”

The book’s central thesis is that we must restructure the global economy, ditch free market ideologies and remake our political systems if we are to have any hope of surviving the devastating effects of a warming climate.

In other words: change or be changed.

Klein began her talk by criticizing the overzealous “euphoria” that followed the December climate talks in Paris.

She showed a photo of several world leaders celebrating after the signing of the final agreement.

“Look at how happy they are,” she said. “Look how sincere.”

The global media praised delegates for finally agreeing, in Paris, that warming must be capped at 1.5 degrees Celsius. But the emission reduction plans of all participating nations — which, by the way, aren’t legally binding — add up to warming levels twice that.

What we got in Paris, Klein said, is “a pretty good definition of safety coupled with a comprehensive plan for disaster.”

Klein, who spent much of her life fighting for economic justice and human rights, felt for a long time that climate change was one global problem she could afford to ignore.

“Let the environmentalists handle that one,” she thought, certain she should focus on more pressing, short-term problems.

Hurricane Katrina was her wake up call. The disaster’s tragic mismanagement, and the public’s anger toward its neglected victims, proved to Klein that global warming is not just about the world getting hotter and wetter.

“It is also about the world getting meaner and uglier,” she said.

So how to fight it?

The auditorium was packed with a typical Boulder crowd: conscientious undergraduates, activists, community environmental groups.

They arrived largely on foot and bike, wearing shorts in the unusual March warmth.

It was a motivated audience if there ever was one — but is motivation enough?

CU student Franky Navarrette, who works with Fossil Free CU and spoke before the talk, certainly thinks so.

Calling Klein’s talk “phenomenal” and “beyond expected,” Navarrette said, “We not only walk away with a deep understanding of the urgency of the issue, but for once, a profound hope that a better world is indeed possible.”

He also added that, though CU has declined to divest multiple times before, the November election offers a chance to reform the Board of Regents.

“Let’s make sure our Democrat regents are elected this fall across the state, so that we not only divest, but we address all the issues on our campus of justice and sustainability!” he said.

Even Klein, so careful not to over-congratulate token actions, remains doggedly optimistic.

She called on the audience to push for divestment from fossil fuels, which the students of Fossil Free CU are already doing. She advocated against the throwaway culture and all it discards, from recyclable materials to refugees to entire countries. She pushed for an embrace of public goods, renewable energy and collective, local action.

Klein, who is Canadian, harshly criticized President Barack Obama’s free trade deal, the Trans Pacific Partnership.

Stipulations in the agreement would allow corporations to sue national governments over environmental protections that hurt their businesses.

Klein said, “Hillary Clinton says she is not a single issue candidate and this is not a single issue country.” But eliminating the massive power of corporations, she said, may well be the single issue that affects all the others.

She then offered words of encouragement to Bernie Sanders, to thunderous applause.