The title was in suspended animation so I added the answer from the article. The article is trying to make its primary audience, the Americans, easier by converting it to miles.
Surely the standard unit for this sort of thing is multiples of well known large lakes or seas?
But quoting a value of 4.4 x 10^19 liters is meaningless for most people.
"Of course, that's 22,000,000,000,000,000,000 two-liter soda bottles!"
So cubic miles seems like a reasonable unit for this pop-science article, despite the fact that you likely wouldn't use it in a published journal article.
Yeah. Long. I doubt most people can eyeball something in the distance and say with accuracy "yeah that is about a mile away" because a mile is really long and people are bad at estimating things. Now do it for 10 miles.
A relatable example like someone has mentioned "its about 10 dead seas worth" would have been a better play.
In this case, 1.48 * 10^20 CCC
Like for a million cubic miles, I know that's a cube with 1,000 mile sides. That's like New York to Miami (don't ask me about cities in Europe...okay I'll go out on a limb: Paris to Rome?). I can visualize that cube of water on a globe.
But how many liters or gallons is that? A lot! But billions? Trillions? I probably would instinctively say billions, but with a tiny bit of mental arithmetic I'm suspecting it's up in the trillions.
edit: I came back to confess that indeed I am an ignorant American who has no intuitive sense of exaliters. My SI volume comfort zone doesn't extend much past teraliters.