An air of regret and lost opportunity permeates “An Inconvenient Sequel: Truth to Power,” the terribly titled sequel to “An Inconvenient Truth,” the Academy Award-winning documentary from 2006 highlighting Al Gore’s crusade to save the planet.

In this follow-up, the former vice-president tells a story about a woman walking past him, doing a double-take, walking past again, and finally blurting out: “If you dyed your hair, you’d look just like Al Gore!”

In another segment, Gore is in the den of the Tennessee home where he grew up. He holds a framed note written by one of his daughters when she was very young, and ruefully reads her list of pros and cons for her father running for president, when he was first considering it in the late 1980s. It’s a poignant moment. Almost melancholy.

And after Donald J. Trump is elected president, Gore notes, “There have been a lot of setbacks. So now we have another one.”

(The spectre of Trump and his gleefully clueless approach to facts looms from time to time in the film, via audio clips in which he dismisses concerns about the environment as a very low priority.)

Directed in disjointed and sometimes unfocused fashion by Bonni Cohen and Jon Shenk, “An Inconvenient Sequel: Truth to Power” is nonetheless worth a viewing, if only for the continued, irrefutable, scientifically sound reminders that humankind continues to harm the planet in shocking and sobering ways.

Of course we see the time-honored visuals of glaciers melting and once fertile land cracking apart and permanent clouds of smoke enveloping cities in Asia — but if anything, the video of floodwaters rushing through the streets of Miami and lower Manhattan and the graphics detailing the rise in temperatures around the globe are even more jolting.

Ever the Southern gentleman and still slightly awkward at times when greeting folks, Gore is nevertheless infinitely more relaxed and more comfortable in his own skin than he was before he became a “recovering politician,” as he jokingly refers to himself. Why, he even loses his temper at one point, with sweat beads forming at his temples as he rails against the ignorance and stubbornness of climate change deniers.

If Gore had shown more of this side of himself back in the day and not been such a robotic politician, he wouldn’t have needed Florida to win the 2000 election.

“An Inconvenient Sequel” follows Gore around the globe, as he meets with young (and practically worshipful) recruits to the cause, huddles up with world leaders and of course delivers his famous slide show, which is continually updated to reflect the latest developments on the environmental front — almost all of them negative.

Without ever coming out and saying, “I told you so,” Gore keeps reminding us: He told us so.

He told us a decade ago the planet was in increasingly dire shape and things would only get worse if we didn’t band together and do more to reverse the course — but we didn’t do enough, and things ARE worse, and he told us so.

There’s no attempt to give the opposition a voice. (Even if you think climate change deniers are in the same league as Flat Earthers and Truthers, why not give one or two of them a voice, if only to highlight the often ridiculous “logic” behind their beliefs?) This is an advocacy film, through and through.

“An Inconvenient Sequel” ends with a call to arms, with the filmmakers urging viewers to sign up and get involved. These final scenes actually undercut the power of the film’s message, making it seem as if we’ve been watching an infomercial all this time.

An infomercial with an important message and worth our time, to be sure, but an infomercial nonetheless.

 

★★★

Paramount Pictures presents a documentary directed by Bonni Cohen and Jon Shenk. Rated PG (for thematic elements and some troubling images). Running time: 100 minutes. Opens Friday at local theaters.