Millions of people have been forced to flee their homes in Syria since the ongoing crisis began in March 2011.

Of the refugees, the United Nations Refugee Agency (UNHCR) estimates that 1.5 million are children. That's nearly the entire population of Manhattan.

An exodus of this magnitude is beyond most people's imaginations unless you're there to witness it. Try to imagine what it would be like if every single person on the island of Manhattan fled their homes. Can you? That would account for JUST the children displaced in Syria. It's an exodus and disaster we have trouble comprehending.

UNHCR, in collaboration with the Hamdi Foundation, has produced a video to help you understand the travesty. "What if Manhattan..." asks: How would the world respond if the refugee crisis affecting the children of Syria were happening to the people of Manhattan.

This is what it would look like. And the world would notice.

Add this video to the growing body of advocacy materials — like Save the Children's second-a-day video that took the conflict from Syria and placed it in London — that scream out for the West to pay attention to one of the worst humanitarian crises of the 21st century.