By Brian Lowry

CNN

(CNN) -- The assist surely wasn't intentional, but Donald Trump has provided Al Gore with a heck of an ending for "An Inconvenient Sequel: Truth to Power," adding a sense of urgency to this dutiful follow-up to the documentary that officially wedded Gore, Hollywood and environmental activism, "An Inconvenient Truth."

It's hardly a spoiler that the hopeful notes that Gore sounds during this decade-later sequel about climate action -- including his efforts to smooth the way for the Paris Climate Accords -- are delivered a conspicuous setback by Trump's decision to pull out of the agreement. In terms of rallying the faithful, it's hard to think of anything that would do more to call attention to the film and Gore's 25-year crusade.

Working with new directors, Bonni Cohen and Jon Shenk, but hitting many of the same themes, the movie follows Gore around the globe -- India, Silicon Valley, Greenland, the Philippines -- as he meets with leaders and presses the case about the threat of climate change, as he seeks to educate activists. It's a variation of the presentation he delivered in the earlier film, presented with alternate amounts of humor, exasperation, faith and flashes of anger.

Gore also finds support close to home, from the mayor of Miami (he visits when the tide has risen, flooding the streets) to the mayor of a conservative Texas town that has aggressively moved toward renewable energy.

Yet while it's interesting to see these exchanges, there's no escaping how climate science has been politicized. As a consequence, the main danger with the film -- and indeed, all similar fare -- is the perception these efforts risk simply preaching to the choir.

In an opening sequence, Gore has a terse exchange with Oklahoma Sen. James Inhofe during testimony before a Senate committee in 2007, emblematic of the science denialism that has complicated the debate and frustrated the goal of spurring a public-policy shift.

If "Inconvenient Truth" felt groundbreaking, the sequel comes on the heels of a wave of documentary films exploring aspects of the topic, from Leonardo DiCaprio's "Before the Flood" to the recent Netflix project "Chasing Coral," about disappearing ocean reefs.

As celebrity climate warriors go, Gore was a pioneer, and he's inevitably cast as the hero in this story, working behind the scenes to help pave the way for the Paris accord. But there's no questioning his commitment to the cause -- "a mission," he says, "that I have dedicated myself to."

Viewed in concert with the original, that sense of genuine dedication is one of the more enduring aspects of "An Inconvenient Sequel." And while Gore paints a fairly rosy longterm picture based on the progress he sees, the great unknown is whether he'll feel motivated to do a third film a decade from now, and not incidentally, how high average temperatures and the sea level will be by then.

"An Inconvenient Sequel: Truth to Power" opens in limited release in the U.S. on July 28.