The challenges are enormous — but we should not forget the benefits. With the right approach, refugees and migrants can bring benefits to both their adoptive societies and their home countries. This well-documented upside should not be lost in the debate.

The New York Declaration should be seen in the wider context of new and ambitious international efforts to improve conditions where people live so they are not forced to leave. Central to this is the 2030 Agenda for Sustainable Development, our global plan for peace and prosperity on a healthy planet. We are also pushing to prevent and resolve conflicts — and to sustain peace once the guns fall silent.

The summit will feature testimony from those directly affected. I am especially looking forward to meeting again with an extraordinary young woman I first encountered last month at the Olympic Games in Rio de Janeiro.

Yusra Mardini is Syrian — but she competed on the new refugee team established for athletes who, like millions of other people around the world, have been forced out of their homelands. Before she swam in races, Yusra was in a race to save lives.

Last year, she left Syria on an overcrowded boat. When its engine died, she dove into the Aegean Sea and started pushing the vessel, along with a few other swimmers among the group. It took a gruelling three hours to reach the shore. They arrived exhausted — but they had proven the power of human solidarity to ferry us to safety.

Humanity is together in one boat. Stoking fear, blaming the "other" or scapegoating minorities will only increase the dangers for all.

Wise leaders understand that we should instead endeavour to save everyone, optimize the contributions of each, and steer our common ship to our shared destination: a future of opportunity and dignity for all.

The author is secretary-general of the United Nations.