One sentence will put in perspective for many: "Analysts say that 42 percent of all Syrians, more than New York City’s population, have fled their homes."

More than 2.5 million Syrians have fled the country and another seven million are internally displaced in a country of 23 million. That's about 9.5 million people, compared to about 8.3 million New York City residents.

Al Jazeera created interactive maps that illustrate, accounting for population density, how this type of human exodus would fit into various parts of America. Here's New York City:

Al JazeeraA growing number of Syrian refugees are children.

Now imagine that a quarter of those people left and the rest fled their own homes.

Barnard's next sentence drives the point home: "An equivalent catastrophe in the United States would mean 131 million Americans on the move."

In October, an independent Syrian adviser to aid told Barnardthat Syria “will be reduced to the bottom of the development ladder, along with countries like Somalia and Yemen,” the war continued for another year.

It's well on its way. And given that Syria is "now probably history’s most-documented manmade disaster," as Barnard notes, turning away becoming less and less of an option.