Here is a link to the actual paper.
http://ix.cs.uoregon.edu/~ram/papers/ANRW-2018.pdf
They are claiming a one foot rise in sea level in the next 15 years, which is the *most extreme* prediction from from the Digital Coast project, which is managed by NOAAs Office for Coastal Management.
Then they claim that a one foot rise will put 20-25 percent of Internet cables in NYC under water at a normal day at high tide.
So, their prognosis rests on two unlikely claims.
First, that ocean levels will rise a foot in 15 years.
Second, that 20-25 percent of current Internet cables in New York City are within one foot of high tide levels on a normal day.
Good thing it never rains in NY or people would be without Internet service right now.