There were a lot of big movie stars making the rounds at the Cannes Film Festival, but none loomed larger than Al Gore. Attending a posh dinner for the festival’s 70th anniversary, he hobnobbed with a crowd of A-listers while receiving well-wishes from distributors and filmmakers alike. “The Beguiled” director Sofia Coppola paid her respects, as did Sony Pictures Classics co-president Michael Barker and Los Angeles Times critic Justin Chang.

And so did I. Everyone in the room felt compelled to approach Gore, thank him for his continuing efforts to save the planet, and wish him good luck on the road ahead — which has only gotten rockier with the news that President Donald Trump decided to pull out of the Paris Accord. Back then, just a few weeks ago, Gore was the loftiest figure in a very flashy room; now, he looms even larger.

The 2015 Paris Agreement takes center stage in “An Inconvenient Sequel: Truth to Power,” which finds Gore barreling through a series of negotiations with foreign entities to secure the historic agreement with 195 countries. (The movie opened the 2017 Sundance Film Festival and made its international debut at Cannes.) In scenes far more exciting and constructive than the dry Powerpoint presentations that dominated 2006’s “An Inconvenient Truth,” Gore emerges as a one-man army against climate change skeptics, juggling a laptop and a cell phone as he brokers a deal between India and the American energy company SolarCity to convince the country to join the deal. Whether or not Gore deserves as much credit as the movie gives him, he’s certainly a potent symbol, one who has lost more than one major fight in his storied career, who remains more driven than ever before.

If that message didn’t fully resonate at the movie’s first screening, it certainly does now, as the world reels from Trump’s decision to stymie the progress against global warming, making America one of just three countries — in the less-than-flattering company of Nicaragua and Syria — to withdraw from the pact to minimize carbon emissions. In its latest version, “An Inconvenient Sequel” finds Gore in the wake of the 2016 presidential election, aware of the challenges posed by an anti-science administration but nevertheless compelled to continue his activism.

"An Inconvenient Sequel." Sundance Institute In the aftermath of Trump’s announcement, the filmmaking team has announced plans to return to the editing room to acknowledge the latest setback; as they do that, they will need to continue to foreground Gore’s ongoing resilience if the movie’s going to have the appropriate impact when it comes out in late July. Thanks to Trump, Gore just became the summer’s biggest movie star — and, short of Wonder Woman, one of its most exciting superheroes, a larger-than-life figure whose ongoing efforts speak to the prospects of finding hope in dire situations.

If Trump is steering the planet into a natural disaster movie worthy of Roland Emmerich, Gore has been cast as the nerdy protagonist with the tools to save the world, if only someone will listen to him. “An Inconvenient Sequel” will allow him to have an audience, no matter what Trump does.

As the president continues to solidify his infuriating, retrograde “America First” policies, documentary filmmaking may be one of the strongest weapons for enlightening society to the dangers at hand. Just as Trump whisperer Steve Bannon found a vessel for his crypto-fascist ideals in non-fiction filmmaking, today’s progressive attitudes need a galvanizing outlet that opens minds less through dry argumentation than emotional clarity. Considering its blander predecessor, “An Inconvenient Sequel” is a surprisingly effective means of dragging real-world problems into the cinematic arena by casting Gore in a heroic light. It finds him enmeshed in one messy debate after another, talking through the practical benefits of creating more jobs with green energy while explaining the catastrophes already unfolding around the world in places faced with rising tides.

Sometimes, watching Trump bat away questions about global warming on the news, Gore looks crestfallen — but the movie also shows emboldened by his purpose, feeding off the anxiety around him by refashioning it as a call to arms. It’s ironic to consider just how much Gore became a robotic caricature during his ill-fated 2000 presidential campaign. These days, he leaves a far different impression on the big screen, having aged gracefully into a charismatic, salt-and-pepper-haired figure of confidence who wouldn’t look out of place alongside George Clooney on the red carpet.

This star, however, entered the movies on his own terms. Gore’s efforts in the documentary are only a microcosm of the ones he continues to pursue off-screen. If “An Inconvenient Sequel” successfully rejuvenates enthusiasm for his environmental efforts this summer, it will also set the stage for the battle to come.

"An Inconvenient Sequel: Truth to Power" will screen for free at select theaters June 6, and will be released officially on July 28.