The growing humanitarian crisis is the hot topic as John Key meets Tony Abbott at the South Pacific Forum tonight.

The summit of Pacific leaders is being held in Papua New Guinea's capital, Port Moresby.

Australia's prime minister has headed to PNG after grappling with his country's response to the Syrian crisis back home.

An Australian under-secretary is acting in Mr Abbott's place in the meantime, but the two prime ministers are sitting down for a one-on-one discussion.

"I'll be one of the first leaders obviously to have an opportunity to have an in-depth discussion with him. But this is the continuation of what is an escalating, worsening issue when it comes to both Syria and ultimately ISIS," Mr Key told reporters.

Australia is to take part in air strikes against Syria. New Zealand doesn't have the capacity to join that, but moral support will no doubt be welcome.

This is about survival in the Pacific. - Oxfam Australia chief executive Helen Szoke

"Well, New Zealand's always taken the view that people have, or countries have, the right to do what they think they should do and what they're capable of doing when it comes to defeating ISIS. It's not an option for New Zealand," Mr Key said.

ONE News political reporter Katie Bradford says while New Zealand and Australia have now both agreed to take in more Syrian refugees, it's a potential refugee crisis in the Pacific that leaders at the Pacific Island forum are more worried about.

That is the potential for climate change refugees, and the effects of climate change seeing more people flocking to our shores asking for help.

"This is about survival in the Pacific. It's not about development, it's not about long term issues," said Oxfam Australia chief executive Helen Szoke.

"It's actually about the fact that if we don't take action now and we're not ambitious about that action, that the lives of many people, hundreds of thousands of people in the Pacific, will be affected."

Leaders of Kiribati, Tuvalu and other low lying atolls say New Zealand and Australia just aren't doing enough.

Mr Key disputes that, saying over $1 billion is committed to Pacific development, including on sustainable clean energy projects.

And he doesn't think climate change refugees are an immediate issue.

"Realistically, you're so far into the future that's not an issue that we're going to face in the next year or two," he said.