The American secretary of state, John Kerry, who was invited to the Pacific Islands Forum summit, has sent a video message in which he said it was vital that vulnerable nations prepare for the impacts of climate change.
Mr Kerry's place is being taken by the interior secretary Sally Jewell.
In his video Mr Kerry pledged to ensure a secure future for Pacific states facing the threat of climate change.
The prime minister of Tuvalu, Enele Sopoaga, was delighted with the Kerry message.
"He used two particular words that are critically important to SIS [Small Island States] on climate change. That is irrefutable, that is, referring to the science, and catastrophic, referring to the impacts of climate change. And I think those two words capture it and I am certain we want to appreciate that."
The prime minister of Tuvalu, Enele Sopoaga.