They're the custodians of what some Australian politicians rather patronisingly call "our backyard" — a vast swathe of the Pacific Ocean.

Key points: Pacific Island leaders will want climate change to be front and centre

Pacific Island leaders will want climate change to be front and centre They are likely to seek assurances that Australia will stick with the Paris agreement

They are likely to seek assurances that Australia will stick with the Paris agreement Australia will want to cement its position as the most significant presence in the region

Today leaders of Pacific Island nations will sit down together in Nauru, a speck of a country perched just south of the equator.

They're there for the Pacific Islands Forum leaders' meeting — the pre-eminent gathering of top dignitaries from islands large, small and tiny.

Australia is by far the biggest aid donor in the Pacific and has prided itself on its strategic pre-eminence as the region's "partner of choice".

But some quietly simmering tensions between Australia and its Pacific neighbours are starting to break into the open.

The meeting risks being overshadowed by flare-ups on refugee policy and the battle for influence between China and Taiwan.

Yesterday a TVNZ journalist was detained for four hours after trying to interview a refugee on the island.

There was also a diplomatic confrontation over protocol between China and Nauru, when a Chinese official stormed out of a meeting and was branded "insolent" after not being allowed to speak.

Nauru's President Baron Waqa, chairing the forum, said the delegate "created a big fuss" and held up the meeting for several minutes after other forum leaders were given priority to speak.

"Maybe because he was from a big country he wanted to bully us," Mr Waqa said.

What do Pacific leaders want to talk about?

Any rise in ocean levels could prove disastrous for some Pacific nations. ( Pool Photo via AP: Jason Oxenham )

Climate change will be front and centre in today's meeting.

Many Pacific Island leaders have been warning that the changing climate poses an existential threat to them.

Some of their nations barely poke their noses above the ocean — Tuvalu lists its highest point as 4.6 metres above sea level. Any rise in ocean levels could prove disastrous.

Sorry, this video has expired Samoan PM hits out at climate change sceptics

Perhaps more importantly, these tiny atolls are hugely vulnerable to cyclones which sometime rake the Pacific, and which scientists predict will become more intense as the climate changes.

All the leaders at PIF are set to sign a new security agreement called Biketawa Plus, which labels climate change the "greatest threat" to the livelihoods and security of Pacific people.

But the timing is awkward for Senator Payne.

She's become Foreign Minister courtesy of a coup provoked — in part — by internal turmoil over energy policy.

And while the Pacific might want to make deeper cuts to carbon emissions, some Coalition MPs are urging the new Prime Minister Scott Morrison to tear up the Paris agreement entirely.

The forum is the pre-eminent gathering of the Pacific's top dignitaries. ( Pool Photo via AP: Jason Oxenham )

Australia has already pledged hundreds of millions of dollars to help Pacific Island nations protect themselves against climate change, and may make further commitments at this meeting in Nauru.

But Pacific leaders are likely to seek assurances from Senator Payne that Australia will stick with the Paris agreement.

Some might even publicly demand that the Australian Government do more to cut emissions — although if that happens they'll be careful to stick to diplomatic language.

What does Australia want to talk about?

Foreign Minister Marise Payne will need to walk a delicate tightrope in her first international summit. ( Pool Photo via AP: Jason Oxenham )

The scale of Australia's commitment to the Pacific is beyond question. It's not just the largest aid donor in the region, it's the largest investor as well.

But China has been making inroads, and Australian officials are wary of its strategic ambitions.

Senator Payne will want to use the forum to deepen cooperation on a vast range of fronts, cementing Australia's position as the most significant presence in the Pacific.

Expect plenty of talk about how Australia and Pacific nations will do more together on border security, maritime surveillance and international crime.

Employment opportunities are also scarce in the region, and the Government is gradually opening up Australia's labour market to workers from the Pacific who are hungry for work.

Yesterday Senator Payne announced three more nations — Samoa, Solomon Islands and Vanuatu — will join Australia's Pacific Labour Scheme, allowing their citizens to fill jobs in rural and regional Australia.

But any attempt to subtly push back against China could meet resistance.

Port Moresby's International Convention Centre, which was built though Chinese government aid. ( ABC News: Catherine Graue )

Last week Samoa's Prime Minister took a thinly veiled swipe at Australia, accusing "traditional partners" of taking a "patronising" attitude to Pacific nations which want to deal with China.

Jenny Hayward Jones from the Lowy Institute points out many Pacific leaders dismiss Canberra's warnings about Beijing's strategic intentions.

"Most seek out and welcome China's interest in financing much-needed infrastructure and in funding assistance for health," she wrote in the Interpreter.

And she argues Australia's climate policies will make it harder to stop Pacific nations from drifting into China's orbit.

"Australia wants to convince Pacific Island governments that they need to be more alert to the strategic threat posed by China," she said.

"Pacific Island governments want to convince an Australian government with no policy on reducing carbon emissions that climate change is an existential threat to their populations, and the primary threat to regional security."

Why did a Chinese official storm out of a meeting?

Australia is not the only player in the room who's anxious about China's rise in the Pacific.

About half of the countries that still recognise Taiwan are in the Pacific, and receive generous aid payments from Taipei.

Nauru President Baron Waqa says smaller countries won't be bullied by more powerful ones. ( Reuters: Lucas Jackson )

Beijing is trying to use both the carrot and the stick to lure them away — which means Taiwan and China are caught in constant tussle for influence in the region.

Yesterday those tensions spilled into the open when a senior Chinese official stormed out of a meeting after being refused permission to speak by forum chairman, Nauru President Baron Waqa.

Nauru recognises Taiwan, and had already irritated China by refusing to allow its delegates to enter the country on official passports.

Mr Waqa accused the lower-level official of breaching protocol by trying to speak when priority was to be given to prime ministers, presidents and other high-level delegates.

"He insisted and was very insolent, and created a big fuss, and held up the meeting of leaders for a good number of minutes, when he was only an official," Mr Waqa said.

What does no-one want to talk about?

Refugees are unlikely to feature on the agenda at all during the Nauru meeting. ( Supplied: World Vision )

Several hundred refugees are still living in Nauru — some only a few hundred metres from the airport where leaders are landing.

Last month former workers on the island told the ABC that refugee children were struggling with deteriorating mental health, and were at risk of death.

Yesterday the media spotlight swung back on Nauru's refugees when New Zealand reporter Barbara Dreaver was detained while trying to interview refugees on the island.

Sorry, this audio has expired Refugees have become part of the Pacific Islands Forum: Barbara Dreaver

Human rights groups say the situation is intolerable, and are demanding PIF leaders put the issue front and centre when they meet today.

But almost no Pacific leaders want it on the agenda.

They are wary of being caught up in Australia's charged domestic debate on refugee policy, and worry the PIF leaders' meeting will be side-tracked from issues crucial to their future.

All eyes will be on New Zealand's Prime Minister Jacinda Ardern, who has repeatedly pressed Australia to allow some refugees on the island to resettle in her country.

Expect her to make that offer — once again — in Nauru.

But don't expect Australia's answer to change.