The article indicates the glacier has water running under it besides to raise the ocean level for the entire world would require and nearly infinite amounts of water
As someone already pointed out I believe it’s pure fear porn
This stuff is called “shore-fast ice”. It does have water running under parts of it. However, it is still partially supported by land and is attached to additional ice which is fully supported by land. If, as, or when this ice breaks free of land and slides into the ocean, it will increase the amount of water in the ocean.
The question is not “will the collapse of this glacier raise world sea levels?” The answer to that is simply “yes”.
The question is “by how much will the collapse of this glacier raise world sea levels?”. I don’t know the answer to that; I suspect that you don’t either. And I don’t trust the “climate change” alarmists to answer it honestly.