With their boundless vistas of turquoise water framed by swaying coconut palms, the Carteret Islands northeast of the Papua New Guinea mainland might seem the idyllic spot to be a castaway. 

But sea levels have risen so much that during the annual king tide season, November to March, the roiling ocean blocks the view from one island to the next, and residents stash their possessions in fishing nets strung between the palm trees. 

“It gives you the scary feeling that you don’t know what is going to happen to you, that any minute you will be floating,” Ursula Rakova, the head of a program to relocate residents, said by telephone. The chain could well be uninhabitable by 2015, locals believe, but two previous attempts to abandon it ended badly, when residents were chased back after clashing with their new neighbors on larger islands. 

This dark situation underlies the thorny debate over the world’s responsibilities to the millions of people likely to be displaced by climate change. 

There could be 200 million of these climate refugees by 2050, according to a new policy paper by the International Organization for Migration, depending on the degree of climate disturbances. Aside from the South Pacific, low-lying areas likely to be battered first include Bangladesh and nations in the Indian Ocean, where the leader of the Maldives has begun seeking a safe haven for his 300,000 people. Landlocked areas may also be affected; some experts call the Darfur region of Sudan, where nomads battle villagers in a war over shrinking natural resources, the first significant conflict linked to climate change. 

In the coming days, the United Nations General Assembly is expected to adopt the first resolution linking climate change to international peace and security. The hard-fought resolution, brought by 12 Pacific island states, says that climate change warrants greater attention from the United Nations as a possible source of upheaval worldwide and calls for more intense efforts to combat it. While all Pacific island states are expected to lose land, some made up entirely of atolls, like Tuvalu and Kiribati, face possible extinction.

“For the first time in history, you could actually lose countries off the face of the globe,” said Stuart Beck, the permanent representative for Palau at the United Nations. “It is a security threat to them and their populations, which will have to be relocated, which is the security threat to the places where they go, among other consequences.”

The issue has inspired intense wrangling, with some nations accusing the islanders of both exaggerating the still murky consequences of climate change and trying to expand the mandate of the Security Council by asking it to take action. 

“We don’t consider climate change is an issue of security that properly belongs in the Security Council; rather, it is a development issue that has some security aspects,” said Maged A. Abdelaziz, the Egyptian ambassador. “It is an issue of how to prevent certain lands, or certain countries, from being flooded.”

The island states are seeking a response akin to the effort against terrorism after the Sept. 11 attacks. “The whole system bent itself to the task, and that is what we want,” Mr. Beck said, adding that the Council should even impose sanctions on countries that fail to act. “If you really buy into the notion that the Suburban you are driving is causing these islands to go under, there ought to be a cop.”

As it is, the compromise resolution does not mention such specific steps, one of the reasons it is expected to pass. Britain, which introduced climate change as a Security Council discussion topic two years ago, supports it along with most of Europe, while other permanent Council members — namely, the United States, China and Russia — generally backed the measure once it no longer explicitly demanded Council action. 

Scientific studies distributed by the United Nations or affiliated agencies generally paint rising seas as a threat. A 2007 report by the Intergovernmental Panel on Climate Change, detailing shifts expected in the South Pacific, said rising seas would worsen flooding and erosion and threaten towns as well as infrastructure. Some fresh water will turn salty, and fishing and agriculture will wither, it said. 

The small island states are not alone in considering the looming threat already on the doorstep. A policy paper released this month by Australia’s Defense Ministry suggests possible violent outcomes in the Pacific. While Australia should try to mitigate the humanitarian suffering caused by global warming, if that failed and conflict erupted, the country should use its military “as an instrument to deal with any threats,” said the paper. 

Australia’s previous prime minister, John Howard, was generally dismissive of the problem, saying his country was plagued with “doomsayers.” But a policy paper called “Our Drowning Neighbors,” by the now governing Labor Party, said Australia should help meld an international coalition to address it. Political debates have erupted there and in New Zealand over the idea of immigration quotas for climate refugees. New Zealand established a “Pacific Access Category” with guidelines that mirror the rules for any émigré, opening its borders to a limited annual quota of some 400 able-bodied adults between the ages of 18 and 45 who have no criminal records. 

But its position has attracted criticism for leaving out the young and the old, who have the least ability to relocate. Australia’s policy, by contrast, is to try to mitigate the circumstances for the victims where they are, rather than serving as their lifeboat.

The sentiment among Pacific Islanders suggests that they do not want to abandon their homelands or be absorbed into cultures where indigenous people already struggle for acceptance. 

“It is about much more than just finding food and shelter,” said Tarita Holm, an analyst with the Palauan Ministry of Resources and Development. “It is about your identity.”

Ms. Rakova, on the Carteret Islands, echoes that sentiment. A year ago, her proposed relocation effort attracted just three families out of a population of around 2,000 people. But after last season’s king tides — the highest of the year — she is scrounging for about $1.5 million to help some 750 people relocate before the tides come again. 

Jennifer Redfearn, a documentary maker, has been filming the gradual disappearance of the Carterets for a work called “Sun Come Up.” One clan chief told her he would rather sink with the islands than leave. It now takes only about 15 minutes to walk the length of the largest island, with food and water supplies shrinking all the time.

“It destroys our food gardens, it uproots coconut trees, it even washes over the sea walls that we have built,” Ms. Rakova says on the film. “Most of our culture will have to live in memory.”