LE BOURGET, France — The two-week United Nations climate conference outside Paris that drew to an end on Saturday focused on many of the physical dangers associated with climate change: extreme weather, severe drought, the warming of oceans, rain forest destruction and disruptions to the food supply.

But global warming has already had another effect — the large-scale displacement of people — that has been an ominous, politically sensitive undercurrent in the talks and side events here.

Scientists have said that climate change can indirectly lead to migration by setting off violent conflicts. Scholars have made this connection since at least 2007, when they cited climate change as a reason for the war in Darfur, Sudan.

A drought that lasted from 2006 to 2011 in much of Syria has been cited as a factor in the long-running civil war there, fueling a mass migration to Turkey, Lebanon and Jordan, but also to Europe, Canada and, in small measure, the United States.

Europe, in particular, is experiencing the largest influx of migrants since World War II — Germany alone has already taken in nearly a million this year. Jean-Claude Juncker, the president of the European Commission, told world leaders on Nov. 30 that climate change could “destabilize entire regions and start massive forced migrations and conflicts over natural resources.”

The Paris climate accord, adopted on Saturday, calls for developing recommendations “to avert, minimize and address displacement related to the adverse impacts of climate change” — an explicit acknowledgment of the dangers of migration that some of the poorest of the 195 countries involved in the talks had sought to include in the text.

From 2008 to 2014, an average of 26.4 million people were displaced each year by floods, storms, earthquakes and other natural disasters, according to a report released in July by the Internal Displacement Monitoring Center, part of the Norwegian Refugee Council. Most moved within their countries.

“Climate-related displacement is not a future phenomenon,” said Marine Franck, who works on climate change and migration for the United Nations high commissioner for refugees. “It is a reality; it is already a global concern.”

William Lacy Swing, a retired American ambassador who now leads the International Organization for Migration, said that climate change was adding to a “perfect storm” of “unprecedented human mobility,” a result of the quadrupling of the world’s population over the last century and wars, conflicts and persecution that have displaced a record 60 million people.

He said that migration had to be viewed “not as a problem to be solved, but a human reality that has to be managed.”

The United Nations Convention to Combat Desertification — like the climate talks, it grew out of the Earth Summit in Rio de Janeiro in 1992 — and the British Defense Ministry recently cited a 2009 report estimating that 135 million people are at risk of displacement because desertification, the drying out of once-fertile land, will reduce drinking-water supplies and lower coral yields. The problem is most pronounced across a band of Africa, from the Sahel in the west to the Horn of Africa in the east.

By 2020, some 60 million people could move from the desertified areas of sub-Saharan Africa toward North Africa and Europe, the report found; by 2050, about 200 million people may be permanently displaced.

The report was prepared by a research and advocacy organization led by Kofi Annan, the former United Nations secretary general, that shut down in 2010; some of the report’s findings have been disputed. Indeed, the numbers are so staggering that Jan Egeland, the head of the Norwegian Refugee Council, who with Mr. Swing and others spoke at a panel discussion here, took pains to point out that the vast majority of migration worldwide takes place in the developing world.

As early as 1990, a report by the Intergovernmental Panel on Climate Change warned, “The greatest single impact of climate change could be on human migration.”

It was not until 20 years later, at the 2010 United Nations climate conference in Cancun, Mexico, that countries formally agreed that “climate change-induced migration, displacement and relocation” were among the challenges the world faced in adapting to a warmer planet.

In 2012, the Norwegian and Swiss governments established a research entity, the Nansen Initiative, which found that “a serious legal gap exists with regard to cross-border movements in the context of disasters and the effects of climate change.” The initiative has held consultations in four particularly vulnerable regions — Central America, the Horn of Africa, Southeast Asia and the islands of the South Pacific — and plans to recommend a “protection agenda” that may include standards of treatment.

People forced to leave their homes because of climate change are not easily classified under existing human rights, refugee or asylum law. In July, a New Zealand court dismissed a landmark case brought by a man from Kiribati, Ioane Teitiota, who had sought to have his family classified as “climate change refugees.” They were deported in September.