Some of the world's smallest nations will use a Pacific summit this week to push the globe's biggest polluters to finally act on climate change, an issue that threatens their very existence.

Host nation the Marshall Islands wants the Pacific Islands Forum (PIF), which opens in the capital Majuro on Tuesday, to kickstart stalled international efforts to tackle global warming and rising seas.

"We want this to be the Pacific Islands Forum where the region says 'enough's enough'," said Marshall Islands Minister Assisting the President Tony deBrum.

"The Pacific Rim is the source of more than 60 percent of the world's emissions and rising, so this is the key battlefield in the war against climate change. It's time for us to unleash a new wave of climate leadership."

The 15-nation PIF consists mainly of small island states, along with resource-rich Papua New Guinea and regional powers Australia and New Zealand.

It includes the atoll nations of Tuvalu, Kiribati and the Marshalls, where most islands are less than a metre (three feet) above sea level and leaders say climate change is an immediate threat to their people, not an abstract scientific debate.

"Recently waves inundated (our international) airport (and we see) accelerated erosion in most parts of the island," Marshall Islands Foreign Minister Phillip Muller said, adding that changing conditions meant parts of the country were still in the grip of a record-breaking drought.

Some island nations, such as Kiribati, are already talking about the need to migrate to escape rising seas but Muller said the Marshall Islands' population of 55,000 did not want to become climate change refugees.

"We're hoping that we won't have to relocate. That's a choice that we don't want to make," he said.

"We want to work as hard as we can to see if there's a possibility of having our islands continue to exist, that's why we're calling for urgent action from our friends around the world."

Muller said the PIF nations intend to agree on a 'Majuro Declaration' at the summit, which involves taking concrete action on climate change.

The plan is to then present the declaration to UN Secretary General Ban Ki-moon at the General Assembly meeting in New York at the end of September, "to reenergize the international community and make them aware that there are countries that may not be in existence much longer".

While climate change is the central theme of the four-day summit, a raft of other issues will be discussed by the island leaders and dialogue partners attending the event, including diplomats from the United States, China, the European Union, India and Russia.

These include sustainable development, increasing islanders' control of the $4.0 billion a year tuna industry and protecting marine life in the vast ocean territories belonging to PIF members through measures such as shark protection.

The fate of Fiji, which was expelled from the PIF in 2009 after its military regime reneged on a pledge to hold elections, is also likely to be discussed, although readmission is unlikely before a vote scheduled for September next year.