Former US President Barack Obama called on the UN climate conference in Glasgow on Monday to address the risks that island nations face from rising sea levels.
Obama said their tales at the 2015 climate talks had been crucial to the resulting Paris Agreement, which commits countries to holding the rise in the average global temperature to "well below" 2 degrees Celsius above preindustrial levels.
"I have been shaped by my experience growing up in Hawaii," Obama said, adding, "we have to act now to help with adaptation and resilience."
Leaders of island nations at the COP26 summit pressed Obama about the failure of the United States and other Western countries to meet pledges to provide $100 billion a year in climate finance.
"Among others, the USA is woefully short of paying its fair share of climate finance," said Fiji's Prime Minister Frank Bainimarama, adding, "Now we are most vulnerable are told to suck it up and wait."
"Developed nations are failing us," Bainimarama said.
Obama arrived at the climate talks on Monday at the start of the second week of negotiations, which will focus on the nitty-gritty details that need to be agreed by over 190 countries to further implement the Paris agreement.
Obama's aim at the summit is to highlight how far the world has come since the Paris agreement was reached six years ago but stress that more difficult work lies ahead.
He said there is a big gap between the optimistic projection made last week by the International Energy Agency that newly-made country and corporate pledges would limit global warming to 1.8 degree Celsius and the United Nations' forecast that current plans would lead to a "catastrophic" rise of 2.7 degree Celsius this century.
"That makes a big difference for island nations," he said. "Every degree to which we can mitigate counts."
Obama will also meet with youth climate activists on Monday, who he said will need to keep pressure on governments to deliver on climate action.