As Pacific leaders gather in Fiji for the Pacific Islands Forum (PIF) leaders' summit this week, Vanuatu is spearheading a campaign to seek an advisory opinion from the court.

The Melanesian state wants the ICJ to consider whether international law requires countries to meet their emissions-reduction targets to protect the human rights of future generations.

The matter is bound for a vote of the United Nations General Assembly later this year, requiring a majority to pass.

Climate campaigners believe such an opinion would strengthen demands on wealthy and high-emitting nations to cut their greenhouse gas use and reduce future warming.

Speaking on the eve of the leaders' summit, NZ Prime Minister Jacinda Ardern said New Zealand was supportive on principle.

"This would be one of a number of measures that ... those who are most climate-affected are seeking to take to ensure that those who have the greatest power and the largest impact on climate emissions reduction, (to) make sure that they are doing their bit," she said.

Australia - which has lifted its emissions targets under Anthony Albanese's government - has also joined the chorus of support.

"We are supportive of the process," Pacific Minister Pat Conroy said. "And we applaud Vanuatu taking it to the UN General Assembly".

"This is a really important resolution that will help increase momentum for action on climate change."

Gaining the support of Australia and New Zealand is a success for the grassroots campaign, which sprung from Pacific students concerned for their homes' future.

Vishal Prasad, a campaigner with Pacific Islands Students Fighting Climate Change, said the support was "promising and welcome".

"We hope to see Australia's support confirmed alongside other PIF leaders this week, and look forward to the country playing a leading role in championing the campaign," he said.

Vanuatu's prime minister Bob Loughman told Reuters he wanted an improved speed to climate negotiations and emission-cutting initiatives.

"Time seems totally out of step with the reality of climate change's impact on the lives of Pacific people," he said.

"Our villages, our islands, our women, our young people, our chiefs ... are calling on us, Pacific leaders, to take action to fight this emergency."

While other issues are swirling - not least regional unity in the wake of Kiribati's withdrawal from the forum - climate change remains at the forefront of the PIF agenda.

Global warming is an existential threat to several low-lying Pacific countries, and, if unchecked, will cause major ecological and economic damage to the developing region.

Officials in Suva say Mr Albanese's election on a climate platform was promising.

"They're saying the right things," one told AAP, "and now ... everyone is waiting to see whether there's follow-through."

Speaking at an event in Sydney prior to his departure for Fiji, Mr Albanese said he wanted Australia to "be a trusted global partner on climate action".

Australia is also gunning to host a first UN climate summit on behalf of the Pacific, "to elevate and prioritise issues which impact our region the most".

Australian Associated Press