Where is the rest of the world?

I have just completed watching season 1 of 3%. The series depicts a society divided into "two worlds", the vast majority living in a run-down slum, while the titular 3% enjoy life on a lush island named Maralto.

Maybe I missed it, but what has happened to the rest of the world? Is it still there? Is it irrelevant because of a variety of reasons (distance, politics, …)? Are the two "worlds" supposed to represent the entirety of mankind, scaled down to a manageable (in terms of presentation) amount of people?

UPDATE: When the city is seen occasionally, it appears like this:

(screencap from 3% episode 2×5)

That is, the big city is in some kind of a very deep crater, there is a building run by the people from Maralto on the edge of the crater, other than that, there appears to be a lifeless desert around. To get to the island, one has to take a submarine, but how people get from the building on the crater edge to the sea has not been shown to the point till which I have been watching so far.