A scholar of Pacific geopolitics says the US withdrawal from the Paris Agreement leaves the door open for China to increase its influence in the Pacific.
The US President Donald Trump announced the pullout this week saying the agreement aimed at reducing global warming disadvantaged the United States and that he hoped to see a better deal.
China's president Li Keqiang said fighting climate change was a global consensus and an international responsibility.
Anna Powles of the Massey Centre for Defence and Security Studies said Donald Trump's announcement sends a strong signal to island countries in their climate change fight.
"This is a very clear message that the US is no longer a partner for Pacific states but who do they look to? Will they look to China which is stepping up very strongly as a climate leader? That obviously will have flow on effects in terms of China's influence and soft power in the region," she said.
But Dr Powles said the US withdrawal also raises other questions like whether China will keep its climate funding commitments.
Region "more determined" over climate change
The Pacific Islands Forum said island countries are more determined to take serious action over climate change following the United States' withdrawal from the Paris Agreement.
The president of the Federated States of Micronesia, Peter Christian who chairs the Forum, said island countries are now more determined and committed to taking serious action to address climate change and remain steadfast in their obligations under the agreement.
He said the deal offers the best global platform to address the causes of climate change and mitigate its effects.
Mr Christian said the US withdrawal is not surprising as Mr Trump had made his intentions known earlier.
"The United States' withdrawal from the Paris Climate Agreement is not surprising as President Trump had made known his intentions to jettison United States' environment for the sake of his economy," said Mr Christian.
"We who are most vulnerable must become more committed to the principal that the Paris Agreement is still our best avenue to finding solutions to slow down and eventually stop the damage to climate and environment."
"Global leadership on climate change is at a critical juncture," he said.
"The Pacific Islands Forum will continue to support Forum Member, Fiji's COP 23 Presidency and will continue working with others who are committed to the Paris Agreement to address the greatest emergency for our planet to date."