Winston Peters has downplayed the impacts of climate change at the Pacific Islands Forum in Tonga. (Ben McKay/AAP PHOTOS)

New Zealand Prime Minister Chris Luxon’s debut at the Pacific Islands Forum has been overshadowed by his deputy, who has doubled down on his climate denialism.

Deputy Prime Minister and Foreign Minister Winston Peters attended three days of the PIF summit in Tonga before Mr Luxon’s arrival.

On his final day, he downplayed the impact of humanity and industrialisation on the climate by saying “for thousands and thousands and thousands of years there has been climate change”.

At the same press conference, he also pointed out “there are a number of Pacific islands that are actually growing”.

Arriving back in Wellington and as acting prime minister in parliament, he then disputed climate science from his own government agency.

“I can’t think of anyone that agrees with NIWA (National Institute of Water and Atmospheric Research) on that matter worldwide,” he said.

The comments have outraged New Zealand’s opposition parties, and privately, many Pacific delegates in Nuku’alofa.

United Nations Secretary General Antonio Guterres also spent a week in Samoa, New Zealand and Tonga arguing for vast and swift action to reduce fossil fuel use.

Labour leader Chris Hipkins labelled the remarks from New Zealand’s top diplomat “an embarrassing new low”.

“I can’t believe that in 2024 we’re still dealing with climate deniers when there is so much overwhelming evidence that burning fossil fuels and other human activities are warming our world,” he said.

“We cannot adapt our way out of the crisis without reducing emissions.”

Asked about his deputy’s climate gaffes, Mr Luxon said Mr Peters was “absolutely not” a climate denier, and neither was he.

“I believe in human induced climate change, for sure,” Mr Luxon said.

Since taking office in November, the coalition led by Mr Luxon has slashed climate funding from the previous Labour government and plans to allow exploration for oil and gas.

He argues oil and gas will be needed to meet New Zealand’s growing energy needs.

Mr Luxon defended New Zealand’s climate credentials by pointing to the fact that 87 per cent of electricity is generated by renewables, dismissing domestic critics as “within the Wellington bubble”.

When not hosing down the climate spat, Mr Luxon met with various Pacific leaders in Nuku’alofa on Wednesday, and pledged $NZ110,000 ($A101,000) towards women’s rugby on outer Tongan islands.