Mr. Ban has said he wants countries to renew their commitment to a 1951 refugee convention that requires countries to offer protection to civilians fleeing war and persecution. That convention is widely flouted, including by European countries, whose leaders were once the driving force behind such a push at the end of World War II, when Europeans were the ones seeking refuge.

Mr. Ban has repeatedly called on world leaders to accept refugees, but his pleas have been met with reluctance and political and diplomatic maneuvers devised to ease the burden on European governments.

In March, at a refugee resettlement conference, United Nations officials said close to half a million Syrians needed new permanent homes away from the region. But few countries pledged to take them in, prompting a strongly worded rebuke from international aid groups. Instead, the European Union began in April to deport asylum seekers to Turkey, part of a political deal that human rights groups said was fraught with legal problems.

The report that Mr. Ban issued this week also pressed countries to start negotiating a deal to embrace migrants who are crossing borders for reasons other than war, including “hazards related to climate change.” Those discussions, which he said he hoped would start this year, are likely to be even thornier.

In 2015, more than 19 million people were displaced by natural disasters, according to a report published Wednesday by the Internal Displacement Monitoring Centre, more than double the 8.6 million displaced by conflict.

Most of the world’s four million Syrian refugees live in countries in the region: Turkey, Lebanon and Jordan.

Canada has offered visas to more than 48,000 Syrians, according to the United Nations, and is also allowing private groups to sponsor Syrian families. More than 400,000 Syrians sought asylum in Germany last year, and Brazil has issued nearly 8,500 humanitarian visas to Syrians.