Photographer James Balog and his team were hanging out on a glacier when their camera caught something incredible. They were in Greenland, gathering footage from the time-lapse cameras that had been positioned all over the Arctic Circle for several years.

They were also there to film footage for a documentary. And, while they were hoping to catch some interesting moments on camera, no one anticipated a massive chunk of glacier to break off and flow into the water right in front of their eyes.

It was the biggest such event ever shot.

Balog and his colleagues waited by for about an hour and 15 minutes, watching as a block of ice the size of lower Manhattan melted away, surrounded by ice-equivalent skyscrapers two to three times taller.

As far as anybody knows, this was an unparalleled geological disaster, and they got it all on video. It won’t be the last time something like this occurs.

But once upon a time, Balog was openly dubious of the “global warming” phenomenon.

Balog’s reputation as a conservationist and environmental photographer dates back to the early 1980s. And for over 20 years, he’d sneered at climate change alarmists crying, “The sky is falling!” “The sky is falling.”

“I didn’t think people could change the fundamental physics and chemistry of this massive globe. In the 2012 documentary film “Chasing Ice,” he emphasized that it did not appear realistic or practicable.

There was an excessive margin of error in the computer calculations, and there were just too many other important issues concerning our lovely planet. He believed that these histrionic doomsayers were diverting attention away from the genuine concerns.

That was then.

Balog didn’t become a believer until 2005.

National Geographic sent him on a photo excursion to the Arctic, and his first journey north was enough for him to observe the devastation firsthand.

“It was about actual tangible physical evidence that was preserved in the ice cores of Greenland and Antarctica,” he explained in a 2012 interview with ThinkProgress. “That was the smoking pistol, demonstrating how far beyond normal, natural variation the world has grown. And that’s when I realized this was a significant issue that needed to be addressed.

Some of the data may have included the fact that more Arctic landmass has melted away in the last 20 years than in the preceding 10,000 years.

Watch the footage of the glacier’s calving below: