It’s all very well for us to write about glaciers calving, or even show it from above. But to really understand what happens when an iceberg breaks off from its parent glacier, you have to see it from the ground. Which is why this scene from the documentary Chasing Ice is so mindblowing. From this perspective, you can tell that the shelf of ice that’s sliding away from the glacier here is literally the size of a city. Filmmaker James Balog compared it to “Manhattan breaking apart in front of your eyes.”

This is the largest glacier breakup ever filmed, and the filmmakers would like you to know that yes, you should be worried. Not because of this particular breakup — as freaky as it is, that massive avalanche of ice isn’t going to come crush your home or anything. But climate change is altering these Arctic landscapes rapidly and irreversibly. It’s awe-inspiring, but it’s scary as hell too.