Ralph Regenvanu said Australia's long-held argument that it's only responsible for cutting the greenhouse gases it emits within its borders "is no longer tenable" following the International Court of Justice opinion delivered in July.
Speaking to journalists on the sidelines of the Pacific Islands Forum, Mr Regenvanu said the World Court's advisory opinion specified the UNFCCC Paris Agreement was not the only framework on climate change countries must abide by going forward.
"The argument Australia has been making, that the domestic transition is sufficient under the Paris Agreement, is untenable," he said on Wednesday.
Australia was decarbonising its own economy "very fast", he added, while reiterating cutting domestic emissions was no longer enough.
The non-binding advisory opinion from the ICJ, initiated by a group of Pacific law students and spearheaded by Vanuatu, specifies fossil fuel production could count towards the host country and constitute an "internationally wrongful act".
The remarks land as Australia prepares to make a final approval decision on Woodside's North West Shelf major gas project that would allow it to operate out to 2070, with reports a call could be made within days.
Mr Regenvanu was attending a side event making the case for a 100 per cent renewables-powered Pacific, with the minister speaking alongside Tuvalu Prime Minister Feleti Teo to launch a discussion paper on the matter, a joint effort of Australia's Smart Energy Council, Island Minds Vanuatu and the Renewable Energy Council Asia-Pacific.
Palau President Surangel Whipps Jr has also been championing the cause, and while recognising small Pacific island states like his have contributed little to climate change, he "has long believed the best form of leadership is leadership by example".
A fully renewables-powered region could become a signature initiative of 2026 United Nation climate talks, its proponents argue, were Pacific island states and Australia successful in securing co-hosting rights from a competing bid from Turkey.
Prime Minister Anthony Albanese said he and his counterparts at the Pacific Islands Forum were universally aligned on bringing the Conference of Parties event to the climate-vulnerable region.
Australia is also due to set a 2035 emissions reduction target by the end of the month, a requirement under the Paris Agreement.Â
When questioned if Australia would heed the calls of its island neighbours to cut greenhouse gas emissions as fast as possible, Mr Albanese said action on climate was the "entry fee" to credibility in the Pacific.
Australia has also been trying to secure a security pact with Vanuatu but he and Prime Minister Jotham Napat failed to reach agreement while Mr Albanese detoured via the island nation ahead of the leader talks in Solomon Islands.
